PL-380 - tuning knob broke again :( (also a TP question)
http://picasaweb.google.com/PianoPlayer88Key/TecsunPL380#5418054480389124466
I haven't opened the PL-380 since it broke this time, but based on how it feels I think it broke the same way it did before - the knob itself broke off the little post that fits in the slot on the tuner component.
Also, I have a TP/TA question. I think we all know that salt water is a major conductor of radio signals. I've also heard of people receiving TX AM stations in FL in the daytime, and vice versa, using only their portable radios' stock loopsticks, and have heard of reception of NYC AMs on beaches in SC. Also, from what I've heard, the 9' PVC loop can take a signal on a ULR from completely inaudible to total blocking/desense, massive overload, etc.
Ok... considering all those factors, and the fact that some TPs (and TAs) transmit with MUCH higher power than stations in the USA (several hundred kW to over a MW)... assuming you're using the 9' loop and a good, sensitive radio, not swamped by locals (L.A. DXers need not apply)....
is it possible, if you're on the beach facing the target station, to actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly higher) high-power (250kW+) TP stations across the salt water?
Oh.... I should mention that DXing KNOM and KICY from the eastern tip of Russia/Siberia does NOT count! :D
(And what's Gary DeBock's best TA, TNP (trans-north-pole) or TE (trans-equator) catch so far? ;) )
Well.... it happened. again. :(
I grabbed my PL-380 the other day... only to discover that the tuning knob had broken again (the same way as before - I repaired it once), and is now spinning in place, without serving any function... and there's no "clicks" when turning it, either, like there is with the volume knob.
This is the second time the tuning knob on my PL-380 has broken. On the contrary, the volume knob is still holding up & functioning perfectly fine. So, is there anything I can do about this to prevent it from happening again? (The radio is still tunable with the keypad, but some other functions require the tuning dial.)
I'm hoping to do some other modifications to this PL-380 (implementing Scott Willingham's mod, & putting a 5"x0.5" (or 4"x0.25") Amidon-61 ferrite bar in the battery compartment (replacing the stock bar), for example), but considering how flimsy some parts seem to be, I'm wondering if I should start looking at other options? I've already ruled out several, like the PL-310, PL-360, PL-300WT, DT-400W, SRF-M37W, ICF-2010, etc, for various reasons, including not-as-good selectivity, no multiple bandwidths, severe soft mute, among other things. I really would prefer not to buy another radio at this time, though, but there are some issues that really need to be corrected, including the flimsy tuning knob, having some "blank" frequencies with a 45-50dBu noise floor when I'm not within 1/10 mile of a 50kW IBOC blowtorch (instead of the 15dBu typical in rural areas / faraday cages), still too much soft mute / audio pumping on fringe/borderline signals (especially annoying when listening to a station that has co-channel interference when the two stations' carrier frequencies aren't exactly synchronized), among other things.
I really want to like this PL-380, though... the selectivity is, to put it mildly, amazing, except when faced with extremely strong signals. Even so, compared to my previous radio, a Panasonic RQ-SW20... well, it's NO comparison. (The RQ-SW20 is about as wide as the Sony SRF-M37W.) It's just that some stations that should be clearly listenable on this radio are pushed below the raised noise floor due to strong locals > 150-200 kHz away.
Is it time to toss my PL-380 en la basura, or is there anything I can do? :(
Ok... considering all those factors, and the fact that some TPs (and TAs) transmit with MUCH higher power than stations in the USA (several hundred kW to over a MW)... assuming you're using the 9' loop and a good, sensitive radio, not swamped by locals (L.A. DXers need not apply)....
is it possible, if you're on the beach facing the target station, to actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly higher) high-power (250kW+) TP stations across the salt water?
Oh.... I should mention that DXing KNOM and KICY from the eastern tip of Russia/Siberia does NOT count! :D
(And what's Gary DeBock's best TA, TNP (trans-north-
So is there nothing that I can do about it? My dad seems to think it's a poor design, btw. Should I contact anon-co to see if I can get a replacement knob? Also has anyone else had their tuning knob break?
http://picasaweb.google.com/ PianoPlayer88Key /TecsunPL380# 5418054480389124 466
I haven't opened the PL-380 since it broke this time, but based on how it feels I think it broke the same way it did before - the knob itself broke off the little post that fits in the slot on the tuner component.
Also, I have a TP/TA question. I think we all know that salt water is a major conductor of radio signals. I've also heard of people receiving TX AM stations in FL in the daytime, and vice versa, using only their portable radios' stock loopsticks, and have heard of reception of NYC AMs on beaches in SC. Also, from what I've heard, the 9' PVC loop can take a signal on a ULR from completely inaudible to total blocking/desense, massive overload, etc.
Ok... considering all those factors, and the fact that some TPs (and TAs) transmit with MUCH higher power than stations in the USA (several hundred kW to over a MW)... assuming you're using the 9' loop and a good, sensitive radio, not swamped by locals (L.A. DXers need not apply)....
is it possible, if you're on the beach facing the target station, to actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly higher) high-power (250kW+) TP stations across the salt water?
Oh.... I should mention that DXing KNOM and KICY from the eastern tip of Russia/Siberia does NOT count! :D
(And what's Gary DeBock's best TA, TNP (trans-north-pole) or TE (trans-equator) catch so far? ;) )
--- In ultralightdx@yahoogroups. com, "Stephen" ...> wrote:
>
> Well.... it happened. again. :(
>
> I grabbed my PL-380 the other day... only to discover that the tuning knob had broken again (the same way as before - I repaired it once), and is now spinning in place, without serving any function... and there's no "clicks" when turning it, either, like there is with the volume knob.
>
> This is the second time the tuning knob on my PL-380 has broken. On the contrary, the volume knob is still holding up & functioning perfectly fine. So, is there anything I can do about this to prevent it from happening again? (The radio is still tunable with the keypad, but some other functions require the tuning dial.)
>
> I'm hoping to do some other modifications to this PL-380 (implementing Scott Willingham's mod, & putting a 5"x0.5" (or 4"x0.25") Amidon-61 ferrite bar in the battery compartment (replacing the stock bar), for example), but considering how flimsy some parts seem to be, I'm wondering if I should start looking at other options? I've already ruled out several, like the PL-310, PL-360, PL-300WT, DT-400W, SRF-M37W, ICF-2010, etc, for various reasons, including not-as-good selectivity, no multiple bandwidths, severe soft mute, among other things. I really would prefer not to buy another radio at this time, though, but there are some issues that really need to be corrected, including the flimsy tuning knob, having some "blank" frequencies with a 45-50dBu noise floor when I'm not within 1/10 mile of a 50kW IBOC blowtorch (instead of the 15dBu typical in rural areas / faraday cages), still too much soft mute / audio pumping on fringe/borderline signals (especially annoying when listening to a station that has co-channel interference when the two stations' carrier frequencies aren't exactly synchronized), among other things.
> I really want to like this PL-380, though... the selectivity is, to put it mildly, amazing, except when faced with extremely strong signals. Even so, compared to my previous radio, a Panasonic RQ-SW20... well, it's NO comparison. (The RQ-SW20 is about as wide as the Sony SRF-M37W.) It's just that some stations that should be clearly listenable on this radio are pushed below the raised noise floor due to strong locals > 150-200 kHz away.
>
> Is it time to toss my PL-380 en la basura, or is there anything I can do? :(
>
BTW I repaired it once about a month or two ago, and this is the second failure of the same part.
Also I've been considering doing a loopstick mod for this radio (using an Amidon-61 bar in the battery compartment), but I'll probably hold off until after I get my current PL-380 repaired or replaced. (Also I was hoping someone else would be doing experiments on that before I do. There already have been external slider experiments and internal stock stick rewinding experiments. I thought someone besides me had mentioned something about experimenting with a loopstick in the battery compartment, but I haven't heard anything about that since. (I'll see if I can find the post.... but browsing through the messages doesn't seem to turn up anything, and search isn't working at all.)
I sometimes have wanted to be able to use the radio in vertical orientation. As we know the way the loopstick is currently configured makes it impractical. I had a couple ideas for making it possible, though. One is to basically make an air-core loop inside the cabinet running around the perimeter, and have a way to switch from one antenna to the other. If I remember correctly, though, someone said that wouldn't be practical. My other idea I thought of yesterday, is use a small Amidon-61 loopstick antenna - either a 0.375"x3", a 0.25"x2", or a 0.25"x4" cut to 3" length, mounted on one side of the cabinet. If there was a way to fit one internally, that would be nice, otherwise I would mount it externally, but basically right on the side of the cabinet, either next to the tuning & volume control, or next to the headphone & usb ports. I would also want a way to protect it, possibly by encasing it in something that attaches to the side of the cabinet. Most likely it will NOT be a slider type, as once it's mounted/installed, I will probably have NO access to the coil to adjust it.
Hi Stephen,
Out of twelve PL-380's that have passed through here (for myself and
others), two have had tuning controls with binding rotation (requiring
disassembly, adjustment and/or lubrication), but none have had the tuning control
fail to the point of being unusable. For a rough-tuning PL-380, the usual
culprit is a slightly crooked tuning control scraping the cabinet cutout slot,
and the usual solution is to disassemble the radio, and physically push
the control into a straight position. Occasionally, white lithium grease is
useful to restore free rotation to the mechanical parts of a sticky ULR
tuning control. Since your tuning control has already broken completely, I
would suggest you notify Anon-co that you have received a defective radio, and
ask for repair or replacement under the one-year warranty.
" Also, I have a TP/TA question. I think we all know that salt water is
a major conductor of radio signals. I've also heard of people receiving TX
AM stations in FL in the daytime, and vice versa, using only their portable
radios' stock loopsticks, and have heard of reception of NYC AMs on
beaches in SC. Also, from what I've heard, the 9' PVC loop can take a signal on a
ULR from completely inaudible to total blocking/desense, massive overload,
etc.
Ok... considering all those factors, and the fact that some TPs (and TAs)
transmit with MUCH higher power than stations in the USA (several hundred
kW to over a MW)... assuming you're using the 9' loop and a good, sensitive
radio, not swamped by locals (L.A. DXers need not apply)....
is it possible, if you're on the beach facing the target station, to
actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly
higher) high-power (250kW+) TP stations across the salt water?
Oh.... I should mention that DXing KNOM and KICY from the eastern tip of
Russia/Siberia does NOT count! :D
(And what's Gary DeBock's best TA, TNP (trans-north-(And what's Gary
DeBock's best TA, TNP (tra
Stephen, DXers on ships can routinely receive high-powered AM stations
across ocean paths around local noon at ranges over 1000 miles, during
excellent winter conditions. ZNS1-1540 in the Bahamas has apparently been heard on
Massachusetts beaches this way, and a New Zealand DXer told me that he
could hear some Australian AM stations "across the ditch" around local noon,
during great conditions. Of course a superior gain antenna always helps, but
even with a 9' loop, it's highly unlikely that any TP will be heard on our
west coast at local noon. Speaking of Alaska, I'm sure that the several of
the Russians could be heard in the Aleutian Islands, with an outside
chance of receiving the northern Japanese big guns (like 774-JOUB and 747-JOIB).
As far as my best TA catch so far on the 9' loop, all of the six TA's I've
heard so far would be considered "big guns" on the east coast, and nothing
special. Judging only by the number of mp3 listening "hits" on my Mediafire
account :-) , the most popular would be 693-BBC and 756-DLF. The best T/E
catch would probably be 1296-1ZH, a 2.5 kw Hamilton, New Zealand station
heard on the 36" portable PVC Loop at Grayland, WA last August.
73, Gary
In a message dated 4/3/2010 11:45:56 A.M. Pacific Daylight Time,
pianoplayer88key@... writes:
So is there nothing that I can do about it? My dad seems to think it's a
poor design, btw. Should I contact anon-co to see if I can get a replacement
knob? Also has anyone else had their tuning knob break?
_
http://picasaweb.http://picahttp://picasawebhttp://picasahttp://picasawebhtt_
(http://picasaweb.google.com/PianoPlayer88Key/TecsunPL380#5418054480389124466)
I haven't opened the PL-380 since it broke this time, but based on how it
feels I think it broke the same way it did before - the knob itself broke
off the little post that fits in the slot on the tuner component.
Also, I have a TP/TA question. I think we all know that salt water is a
major conductor of radio signals. I've also heard of people receiving TX AM
stations in FL in the daytime, and vice versa, using only their portable
radios' stock loopsticks, and have heard of reception of NYC AMs on beaches in
SC. Also, from what I've heard, the 9' PVC loop can take a signal on a ULR
from completely inaudible to total blocking/desense, massive overload, etc.
Ok... considering all those factors, and the fact that some TPs (and TAs)
transmit with MUCH higher power than stations in the USA (several hundred
kW to over a MW)... assuming you're using the 9' loop and a good, sensitive
radio, not swamped by locals (L.A. DXers need not apply)....
is it possible, if you're on the beach facing the target station, to
actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly
higher) high-power (250kW+) TP stations across the salt water?
Oh.... I should mention that DXing KNOM and KICY from the eastern tip of
Russia/Siberia does NOT count! :D
(And what's Gary DeBock's best TA, TNP (trans-north-(And what's Gary
DeBock's best TA, TNP (trans-
--- In _ultralightdx@ultralightdxult_ (mailto:ultralightdx@...)
, "Stephen" <pianoplayer88key@pia> wrote:knob had broken again (the same way as before - I repaired it once), and is
Well.... it happened. again. :(
I grabbed my PL-380 the other day... only to discover that the tuning
now spinning in place, without serving any function... and there's no
"clicks" when turning it, either, like there is with the volume knob.contrary, the volume knob is still holding up & functioning perfectly fine.
This is the second time the tuning knob on my PL-380 has broken. On the
So, is there anything I can do about this to prevent it from happening
again? (The radio is still tunable with the keypad, but some other functions
require the tuning dial.)Scott Willingham's mod, & putting a 5"x0.5" (or 4"x0.25") Amidon-61 ferrite
I'm hoping to do some other modifications to this PL-380 (implementing
bar in the battery compartment (replacing the stock bar), for example), but
considering how flimsy some parts seem to be, I'm wondering if I should
start looking at other options? I've already ruled out several, like the
PL-310, PL-360, PL-300WT, DT-400W, SRF-M37W, ICF-2010, etc, for various
reasons, including not-as-good selectivity, no multiple bandwidths, severe soft
mute, among other things. I really would prefer not to buy another radio at
this time, though, but there are some issues that really need to be
corrected, including the flimsy tuning knob, having some "blank" frequencies with a
45-50dBu noise floor when I'm not within 1/10 mile of a 50kW IBOC
blowtorch (instead of the 15dBu typical in rural areas / faraday cages), still too
much soft mute / audio pumping on fringe/borderline signals (especially
annoying when listening to a station that has co-channel interference when the
two stations' carrier frequencies aren't exactly synchronized)he flimsy
tuningI really want to like this PL-380, though... the selectivity is, to putit mildly, amazing, except when faced with extremely strong signals. Even
so, compared to my previous radio, a Panasonic RQ-SW20... well, it's NO
comparison. (The RQ-SW20 is about as wide as the Sony SRF-M37W.) It's just
that some stations that should be clearly listenable on this radio are pushed
below the raised noise floor due to strong locals > 150-200 kHz away.do? :(
Is it time to toss my PL-380 en la basura, or is there anything I can
I have contacted her about it (on April 3) and have yet to receive a response. So is everyone from the group swamping her with orders so she can't respond to my email? ;)
BTW I repaired it once about a month or two ago, and this is the second failure of the same part.
Also I've been considering doing a loopstick mod for this radio (using an Amidon-61 bar in the battery compartment), but I'll probably hold off until after I get my current PL-380 repaired or replaced. (Also I was hoping someone else would be doing experiments on that before I do. There already have been external slider experiments and internal stock stick rewinding experiments. I thought someone besides me had mentioned something about experimenting with a loopstick in the battery compartment, but I haven't heard anything about that since. (I'll see if I can find the post.... but browsing through the messages doesn't seem to turn up anything, and search isn't working at all.)
I sometimes have wanted to be able to use the radio in vertical orientation. As we know the way the loopstick is currently configured makes it impractical. I had a couple ideas for making it possible, though. One is to basically make an air-core loop inside the cabinet running around the perimeter, and have a way to switch from one antenna to the other. If I remember correctly, though, someone said that wouldn't be practical. My other idea I thought of yesterday, is use a small Amidon-61 loopstick antenna - either a 0.375"x3", a 0.25"x2", or a 0.25"x4" cut to 3" length, mounted on one side of the cabinet. If there was a way to fit one internally, that would be nice, otherwise I would mount it externally, but basically right on the side of the cabinet, either next to the tuning & volume control, or next to the headphone & usb ports. I would also want a way to protect it, possibly by encasing it in something that attaches to the side of the cabinet. Most likely it will NOT be a slider type, as once it's mounted/installed, I will probably have NO access to the coil to adjust it.
--- In ultralightdx@yahoogroups. com, D1028Gary@.. . wrote:
>
> Hi Stephen,
>
> Out of twelve PL-380's that have passed through here (for myself and
> others), two have had tuning controls with binding rotation (requiring
> disassembly, adjustment and/or lubrication), but none have had the tuning control
> fail to the point of being unusable. For a rough-tuning PL-380, the usual
> culprit is a slightly crooked tuning control scraping the cabinet cutout slot,
> and the usual solution is to disassemble the radio, and physically push
> the control into a straight position. Occasionally, white lithium grease is
> useful to restore free rotation to the mechanical parts of a sticky ULR
> tuning control. Since your tuning control has already broken completely, I
> would suggest you notify Anon-co that you have received a defective radio, and
> ask for repair or replacement under the one-year warranty.
>
> " Also, I have a TP/TA question. I think we all know that salt water is
> a major conductor of radio signals. I've also heard of people receiving TX
> AM stations in FL in the daytime, and vice versa, using only their portable
> radios' stock loopsticks, and have heard of reception of NYC AMs on
> beaches in SC. Also, from what I've heard, the 9' PVC loop can take a signal on a
> ULR from completely inaudible to total blocking/desense, massive overload,
> etc.
> Ok... considering all those factors, and the fact that some TPs (and TAs)
> transmit with MUCH higher power than stations in the USA (several hundred
> kW to over a MW)... assuming you're using the 9' loop and a good, sensitive
> radio, not swamped by locals (L.A. DXers need not apply)....
> is it possible, if you're on the beach facing the target station, to
> actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly
> higher) high-power (250kW+) TP stations across the salt water?
> Oh.... I should mention that DXing KNOM and KICY from the eastern tip of
> Russia/Siberia does NOT count! :D
> (And what's Gary DeBock's best TA, TNP (trans-north-(And what's Gary
> DeBock's best TA, TNP (tra
>
> Stephen, DXers on ships can routinely receive high-powered AM stations
> across ocean paths around local noon at ranges over 1000 miles, during
> excellent winter conditions. ZNS1-1540 in the Bahamas has apparently been heard on
> Massachusetts beaches this way, and a New Zealand DXer told me that he
> could hear some Australian AM stations "across the ditch" around local noon,
> during great conditions. Of course a superior gain antenna always helps, but
> even with a 9' loop, it's highly unlikely that any TP will be heard on our
> west coast at local noon. Speaking of Alaska, I'm sure that the several of
> the Russians could be heard in the Aleutian Islands, with an outside
> chance of receiving the northern Japanese big guns (like 774-JOUB and 747-JOIB).
>
> As far as my best TA catch so far on the 9' loop, all of the six TA's I've
> heard so far would be considered "big guns" on the east coast, and nothing
> special. Judging only by the number of mp3 listening "hits" on my Mediafire
> account :-) , the most popular would be 693-BBC and 756-DLF. The best T/E
> catch would probably be 1296-1ZH, a 2.5 kw Hamilton, New Zealand station
> heard on the 36" portable PVC Loop at Grayland, WA last August.
>
> 73, Gary
>
>
> In a message dated 4/3/2010 11:45:56 A.M. Pacific Daylight Time,
> pianoplayer88key@... writes:
>
>
>
>
> So is there nothing that I can do about it? My dad seems to think it's a
> poor design, btw. Should I contact anon-co to see if I can get a replacement
> knob? Also has anyone else had their tuning knob break?
> _
> http://picasaweb.http://picahttp: //picasawebhttp: //picasahttp: //picasawebhtt_
> (http://picasaweb.google.com/ PianoPlayer88Key /TecsunPL380# 5418054480389124 466)
> I haven't opened the PL-380 since it broke this time, but based on how it
> feels I think it broke the same way it did before - the knob itself broke
> off the little post that fits in the slot on the tuner component.
>
> Also, I have a TP/TA question. I think we all know that salt water is a
> major conductor of radio signals. I've also heard of people receiving TX AM
> stations in FL in the daytime, and vice versa, using only their portable
> radios' stock loopsticks, and have heard of reception of NYC AMs on beaches in
> SC. Also, from what I've heard, the 9' PVC loop can take a signal on a ULR
> from completely inaudible to total blocking/desense, massive overload, etc.
> Ok... considering all those factors, and the fact that some TPs (and TAs)
> transmit with MUCH higher power than stations in the USA (several hundred
> kW to over a MW)... assuming you're using the 9' loop and a good, sensitive
> radio, not swamped by locals (L.A. DXers need not apply)....
> is it possible, if you're on the beach facing the target station, to
> actually get the GROUNDWAVE signal from low-band (540 to maybe 810 kHz, possibly
> higher) high-power (250kW+) TP stations across the salt water?
> Oh.... I should mention that DXing KNOM and KICY from the eastern tip of
> Russia/Siberia does NOT count! :D
> (And what's Gary DeBock's best TA, TNP (trans-north-(And what's Gary
> DeBock's best TA, TNP (trans-
>
> --- In _ultralightdx@ultralightdxult_ (mailto:ultralightdx@ yahoogroups. com)
> , "Stephen" pia> wrote:
> >
> > Well.... it happened. again. :(
> >
> > I grabbed my PL-380 the other day... only to discover that the tuning
> knob had broken again (the same way as before - I repaired it once), and is
> now spinning in place, without serving any function... and there's no
> "clicks" when turning it, either, like there is with the volume knob.
> >
> > This is the second time the tuning knob on my PL-380 has broken. On the
> contrary, the volume knob is still holding up & functioning perfectly fine.
> So, is there anything I can do about this to prevent it from happening
> again? (The radio is still tunable with the keypad, but some other functions
> require the tuning dial.)
> >
> > I'm hoping to do some other modifications to this PL-380 (implementing
> Scott Willingham's mod, & putting a 5"x0.5" (or 4"x0.25") Amidon-61 ferrite
> bar in the battery compartment (replacing the stock bar), for example), but
> considering how flimsy some parts seem to be, I'm wondering if I should
> start looking at other options? I've already ruled out several, like the
> PL-310, PL-360, PL-300WT, DT-400W, SRF-M37W, ICF-2010, etc, for various
> reasons, including not-as-good selectivity, no multiple bandwidths, severe soft
> mute, among other things. I really would prefer not to buy another radio at
> this time, though, but there are some issues that really need to be
> corrected, including the flimsy tuning knob, having some "blank" frequencies with a
> 45-50dBu noise floor when I'm not within 1/10 mile of a 50kW IBOC
> blowtorch (instead of the 15dBu typical in rural areas / faraday cages), still too
> much soft mute / audio pumping on fringe/borderline signals (especially
> annoying when listening to a station that has co-channel interference when the
> two stations' carrier frequencies aren't exactly synchronized)he flimsy
> tuning
> > I really want to like this PL-380, though... the selectivity is, to put
> it mildly, amazing, except when faced with extremely strong signals. Even
> so, compared to my previous radio, a Panasonic RQ-SW20... well, it's NO
> comparison. (The RQ-SW20 is about as wide as the Sony SRF-M37W.) It's just
> that some stations that should be clearly listenable on this radio are pushed
> below the raised noise floor due to strong locals > 150-200 kHz away.
> >
> > Is it time to toss my PL-380 en la basura, or is there anything I can
> do? :(
> >
>
Jim
Stephen wrote:
I have contacted her about it (on April 3) and have yet to receive a response. So is everyone from the group swamping her with orders so she can't respond to my email? ;)
BTW I repaired it once about a month or two ago, and this is the second failure of the same part.
All this lead me to look for posts about the PL-360, but the search box could not find any. I thought there was some discussion here, and the '360 was lacking other features, perhaps 1 Kc. tuning steps? But it might be the best bet for me to play with an air core loop for AM and LW. - FARMERIK
--- In ultralightdx@yahoogroups. com, "farmerik" .> wrote:
>
> Jim - I am trying to follow along, but I am unsure of the theory behind what you are doing. My goal would be a simple direct connection, like the turns on the internal loop coming out through a couple small holes, and outboard air core loops for AM and LW. It would be much better for fumble fingered folks like me if the radio just had a jack when I bought it, but maybe some young enterprising member here could install the turns on the loop for a fee. The number of turns on the ferrite need to be matched to the number of turns on the air coil loop too right? - FARMERIK
>
> --- In ultralightdx@yahoogroups. com, "jim_kr1s" wrote:
> >
> >
> > --- In ultralightdx@yahoogroups. com, D1028Gary@ wrote:
> >
> > > The idea of fitting a larger loopstick in the battery compartment does
> > seem like the most practical option, given the lack of space elsewhere
> > inside the cabinet.
> >
> > Let me advocate for the Dark Side. Using an external battery defeats the
> > stealth idea. If you're going to hang a battery outside the box, why not
> > hang the antenna outside instead? I have an assortment of ferrite rods
> > here. Compared with the internal rod re-wound with better Litz, adding
> > even a couple of inches of length isn't worth the effort. You still have
> > to twist the radio to orient the antenna, and that's going to be more
> > cumbersome with a battery pack hanging off the side.
> >
> > If you're willing to give up the whip, you can fit a longer rod in the
> > top, but it takes some careful Dremel-work.
> >
> > A better idea IMO is to put a coupling winding of about 15 turns around
> > the center of the internal antenna and make something like my Hoop Loop
> > <http://kr1s.kearman.com/ html/hooploop. html> . It costs less than
> > $10.00 to build. There are smaller quilting hoops (10 inches and 18
> > inches) if 23 inches is too large. As Chris Knight mentioned, our tests
> > at MULDxER 2 <http://kr1s.kearman.com/ html/MULDxER. html> showed a
> > 23-inch Hoop Loop was 10-15 dB better than the PL-380 + Terk (cost =
> > $30.00). You can bring the coupling winding out to pigtails and connect
> > the Hoop Loop with alligator clips. That's what I've been doing while I
> > experiment with different matching transformers. Then you don't have to
> > install a connector. Because it is more tightly coupled, and
> > impedance-matched, even a 10-inch Hoop Loop should outperform the Terk
> > by 6-10 dB (and blow away anything that fits inside the radio), and
> > won't require tuning, twisting, major surgery or special battery packs.
> >
> > 73,
> >
> > Jim, KR1S
> > http://kr1s.kearman.com/ <http://kr1s. kearman.com/>
> >
>
--- In ultralightdx@..., D1028Gary@... wrote:
> The idea of fitting a larger loopstick in the battery compartment does seem like the most practical option, given the lack of space elsewhere inside the cabinet.
Let me advocate for the Dark Side. Using an external battery defeats the stealth idea. If you're going to hang a battery outside the box, why not hang the antenna outside instead? I have an assortment of ferrite rods here. Compared with the internal rod re-wound with better Litz, adding even a couple of inches of length isn't worth the effort. You still have to twist the radio to orient the antenna, and that's going to be more cumbersome with a battery pack hanging off the side.
If you're willing to give up the whip, you can fit a longer rod in the top, but it takes some careful Dremel-work.
A better idea IMO is to put a coupling winding of about 15 turns around the center of the internal antenna and make something like my Hoop Loop . It costs less than $10.00 to build. There are smaller quilting hoops (10 inches and 18 inches) if 23 inches is too large. As Chris Knight mentioned, our tests at MULDxER 2 showed a 23-inch Hoop Loop was 10-15 dB better than the PL-380 + Terk (cost = $30.00). You can bring the coupling winding out to pigtails and connect the Hoop Loop with alligator clips. That's what I've been doing while I experiment with different matching transformers. Then you don't have to install a connector. Because it is more tightly coupled, and impedance-matched, even a 10-inch Hoop Loop should outperform the Terk by 6-10 dB (and blow away anything that fits inside the radio), and won't require tuning, twisting, major surgery or special battery packs.
73,
Jim, KR1S
http://kr1s.kearman.com/
--- In ultralightdx@..., D1028Gary@ wrote:The idea of fitting a larger loopstick in the battery compartment doesseem like the most practical option, given the lack of space elsewhere
inside the cabinet.
Let me advocate for the Dark Side. Using an external battery defeats the
stealth idea. If you're going to hang a battery outside the box, why not
hang the antenna outside instead? I have an assortment of ferrite rods
here. Compared with the internal rod re-wound with better Litz, adding
even a couple of inches of length isn't worth the effort. You still have
to twist the radio to orient the antenna, and that's going to be more
cumbersome with a battery pack hanging off the side.
If you're willing to give up the whip, you can fit a longer rod in the
top, but it takes some careful Dremel-work.
A better idea IMO is to put a coupling winding of about 15 turns around
the center of the internal antenna and make something like my Hoop Loop
<http://kr1s.kearman.com/html/hooploop.html> . It costs less than
$10.00 to build. There are smaller quilting hoops (10 inches and 18
inches) if 23 inches is too large. As Chris Knight mentioned, our tests
at MULDxER 2 <http://kr1s.kearman.com/html/MULDxER.html> showed a
23-inch Hoop Loop was 10-15 dB better than the PL-380 + Terk (cost =
$30.00). You can bring the coupling winding out to pigtails and connect
the Hoop Loop with alligator clips. That's what I've been doing while I
experiment with different matching transformers. Then you don't have to
install a connector. Because it is more tightly coupled, and
impedance-matched, even a 10-inch Hoop Loop should outperform the Terk
by 6-10 dB (and blow away anything that fits inside the radio), and
won't require tuning, twisting, major surgery or special battery packs.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
Jim - I am trying to follow along, but I am unsure of the theory behind what you are doing. My goal would be a simple direct connection, like the turns on the internal loop coming out through a couple small holes, and outboard air core loops for AM and LW. It would be much better for fumble fingered folks like me if the radio just had a jack when I bought it, but maybe some young enterprising member here could install the turns on the loop for a fee. The number of turns on the ferrite need to be matched to the number of turns on the air coil loop too right? - FARMERIK
--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:
--- In ultralightdx@..., D1028Gary@ wrote:The idea of fitting a larger loopstick in the battery compartment doesseem like the most practical option, given the lack of space elsewhere
inside the cabinet.
Let me advocate for the Dark Side. Using an external battery defeats the
stealth idea. If you're going to hang a battery outside the box, why not
hang the antenna outside instead? I have an assortment of ferrite rods
here. Compared with the internal rod re-wound with better Litz, adding
even a couple of inches of length isn't worth the effort. You still have
to twist the radio to orient the antenna, and that's going to be more
cumbersome with a battery pack hanging off the side.
If you're willing to give up the whip, you can fit a longer rod in the
top, but it takes some careful Dremel-work.
A better idea IMO is to put a coupling winding of about 15 turns around
the center of the internal antenna and make something like my Hoop Loop
<http://kr1s.kearman.com/html/hooploop.html> . It costs less than
$10.00 to build. There are smaller quilting hoops (10 inches and 18
inches) if 23 inches is too large. As Chris Knight mentioned, our tests
at MULDxER 2 <http://kr1s.kearman.com/html/MULDxER.html> showed a
23-inch Hoop Loop was 10-15 dB better than the PL-380 + Terk (cost =
$30.00). You can bring the coupling winding out to pigtails and connect
the Hoop Loop with alligator clips. That's what I've been doing while I
experiment with different matching transformers. Then you don't have to
install a connector. Because it is more tightly coupled, and
impedance-matched, even a 10-inch Hoop Loop should outperform the Terk
by 6-10 dB (and blow away anything that fits inside the radio), and
won't require tuning, twisting, major surgery or special battery packs.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
--- In ultralightdx@..., "farmerik" wrote:
>
> Jim - I am trying to follow along, but I am unsure of the theory behind what you are doing. My goal would be a simple direct connection, like the turns on the internal loop coming out through a couple small holes, and outboard air core loops for AM and LW. It would be much better for fumble fingered folks like me if the radio just had a jack when I bought it, but maybe some young enterprising member here could install the turns on the loop for a fee. The number of turns on the ferrite need to be matched to the number of turns on the air coil loop too right? - FARMERIK
I'll try to explain the theory. In a stock PL-300, PL-310 or PL-380, the ferrite rod serves two functions. It has a coil of about 240 uH inductance. On MW and LW, this coil is connected in parallel with a variable capacitor, which is voltage-adjusted. It functions just like the metal variable capacitors that tune your older radios.
It is a characteristic of the two components, coil and capacitor, that they can resonate together across the MW band. You can study up on resonance at Wikipedia or many other sites; what's important to know is that the coil must resonate with the capacitor at any frequency in the MW band.
In addition to forming half of a tuned circuit, the ferrite rod also serves as the MW antenna. If you replace the rod with a coil of the same inductance wound on a toroid, you still have a tuned circuit, but you have a poorer antenna, because the toroid forms a closed magnetic field.
I use the terms impedance and reactance, and the differences may be confusing. If you are interested, it's easy to find books and online sites that explain these terms. For now, let's say the new coil we have installed has an impedance at 1000 kHz of 1500 ohms. The impedance of a coil is directly proportional to its inductance and also directly proportional to the frequency in use. This is true for all coils. The impedance ratio between two or more coils remains the same at any frequency. If Coil A has 1.35 times the impedance of Coil B at Frequency X, A will have 1.35 times the impedance of B at Frequency Y, Z . . .
Our new antenna, let's say the Hoop Loop, is also a coil. In my case it has an inductance of 16 uH. At 1000 kHz it has an impedance of 100 ohms. You obtain the most-efficient transfer of power from one circuit to another when the impedances are the same. Somehow we have to transform the 100 ohms of the antenna to the 1500 ohms of the coil.
If we have a transformer with two windings, one of 60 turns and one of 15 turns, we say the turns ratio is 4:1. We know from theory that the impedance transformation ratio is the square of the turns ratio, so it's 16:1. This gives us the insight needed to calculate the number of turns on the winding that connects to the Hoop Loop. The square root of the dividend of 1500 divided by 100 is 3.873. That's our turns ratio. If the resonant coil has 60 turns, we divide that by 3.873 and round off the result to 15, the number of turns on the winding that goes to the Hoop Loop. Because real-world stuff sometimes doesn't exactly match calculations, we might start with 17 turns and remove one at a time to get the best signal strength.
Note that the number of turns on the antenna (3) is much different than the number of turns on the transformer (15). The antenna is wound in air, while the transformer is wound on a ferrite core. The ferrite core concentrates the magnetic field, so we can achieve more inductance per turn than we can in air, but the coil constituting the Hoop Loop is 23 inches in diameter. That's why we use the ferrite toroid (or rod), instead of making an air-wound transformer, which would be very large (think of an oatmeal-box crystal-set coil).
(Why not make a higher-impedance Hoop Loop and do away with the transformer? Two reasons. First, the 23-inch quilting hoop is only 3/4-inch wide. We like to space the turns to reduce self-capacitance, which limits tuning range, and 3 turns is about right. Also, we'd like to use cheap, flexible speaker wire as the feed line from antenna to radio, and it has a characteristic impedance in the range of 50-75 ohms. We want to match impedances throughout the system as well as possible.)
Thanks to our efforts with a calculator, we now have a resonant antenna system. It should be obvious that the original ferrite-rod antenna coil would electrically mimic the toroidal coil with which we replaced it. But the ferrite rod makes a good antenna, which responds better to strong signals than we want. We want the signals to come only from the external antenna. In fact, the chip is so sensitive, even with a tiny (1/2-inch) toroid, three local stations are still strong with only that toroidal coil in place! I wrapped some anti-static foil (coated so the surface is non-conductive and won't short anything in the radio) around the core to shield it. That helped a little, but the chip is very sensitive.
I went sideways on this project. At first I only wanted to use the Hoop Loop for MW. I installed a jack on the side of the radio so I could disconnect the Hoop Loop for transport. Fitting the jack required removing the internal antenna and the whip. After a few days I began wondering how the radio would work if I made a coil that resonated at LW. Frankly, I didn't expect much, and was very pleasantly surprised to hear so many European BC stations on what is a very small antenna for 153-279 kHz. (One of Gary's nine-footers with the right number of turns would be ideal, but then I'd have to eat in the kitchen and watch TV on the porch.) Fitting a good LW coil inside the box is impossible; they're too big. As I'm hot for LW, I've re-thought the project to use a larger, better MW coil (less loss), which will also go outside the box. If all you want is MW, a smaller coil inside the box (in the spot previously occupied by the internal antenna) is very adequate. Chris and I proved that in Melbourne last week.
You can't have it all. These radios are too small. Adding worthwhile features means giving up something. For what they cost, if you want excellent desktop performance and a portable, buy two radios! Fit one for external antennas and re-wind the antenna in the other.
73,
Jim, KR1S
http://kr1s.kearman.com/
Hi Farmerik,
In answer to your question, the PL-360 does have fixed 3 kHz DSP filtering
(like the PL-300WT/ G8) and "soft mute" set at the same threshold as those
models (and the PL-310). However, the plug-in loopstick system does provide
some interesting possibilities to boost AM sensitivity without performing
any "surgery" on the radio.
In one of many experimental projects here, the PL-360 plug-in loopstick was
disassembled to check the ease of fabricating replacement loopsticks of a
much more serious "caliber." It appears to be a fairly simple matter to
construct multiple plug-in loopsticks, to boost up the PL-360's AM sensitivity
as desired.
Of course, greatly increased AM sensitivity can compensate for a multitude
of shortcomings in the PL-360 itself, so the plug-in loopstick idea could
possibly make the PL-360 a popular Ultralight choice in the future, if the
experimentation proves successful.
73, Gary
In a message dated 4/8/2010 10:36:00 A.M. Pacific Daylight Time,
farmerik@... writes:
All this lead me to look for posts about the PL-360, but the search box
could not find any. I thought there was some discussion here, and the '360 was
lacking other features, perhaps 1 Kc. tuning steps? But it might be the
best bet for me to play with an air core loop for AM and LW. - FARMERIK
--- In _ultralightdx@ultralightdxult_
(mailto:ultralightdx@...) , "farmerik" <farmerik@...> wrote:what you are doing. My goal would be a simple direct connection, like the
Jim - I am trying to follow along, but I am unsure of the theory behind
turns on the internal loop coming out through a couple small holes, and
outboard air core loops for AM and LW. It would be much better for fumble
fingered folks like me if the radio just had a jack when I bought it, but maybe
some young enterprising member here could install the turns on the loop for
a fee. The number of turns on the ferrite need to be matched to the number
of turns on the air coil loop too right? - FARMERIK(mailto:ultralightdx@...) , "jim_kr1s" <jkearman@> wrote:
--- In _ultralightdx@ultralightdxult_(mailto:ultralightdx@...) , D1028Gary@ wrote:
--- In _ultralightdx@ultralightdxult_doesThe idea of fitting a larger loopstick in the battery compartmenttheseem like the most practical option, given the lack of space elsewhere
inside the cabinet.
Let me advocate for the Dark Side. Using an external battery defeatsnotstealth idea. If you're going to hang a battery outside the box, whyhavehang the antenna outside instead? I have an assortment of ferrite rods
here. Compared with the internal rod re-wound with better Litz, adding
even a couple of inches of length isn't worth the effort. You still(http://kr1s.kearman.com/html/hooploop.html) > . It costs less thanto twist the radio to orient the antenna, and that's going to be more> cumbersome with a battery pack hanging off the side.
If you're willing to give up the whip, you can fit a longer rod in the
top, but it takes some careful Dremel-work.
A better idea IMO is to put a coupling winding of about 15 turns around
the center of the internal antenna and make something like my Hoop Loop
<_http://kr1s.http://kr1s.http://kr1s.<Whttp_(http://kr1s.kearman.com/html/MULDxER.html) > showed a$10.00 to build. There are smaller quilting hoops (10 inches and 18
inches) if 23 inches is too large. As Chris Knight mentioned, our tests
at MULDxER 2 <_http://kr1s.http://kr1s.http://kr1s.http_<_http://kr1s.http://kr1s._ (http://kr1s.kearman.com/) >23-inch Hoop Loop was 10-15 dB better than the PL-380 + Terk (cost =
$30.00). You can bring the coupling winding out to pigtails and connect
the Hoop Loop with alligator clips. That's what I've been doing while I
experiment with different matching transformers. Then you don't have to
install a connector. Because it is more tightly coupled, and
impedance-matched, even a 10-inch Hoop Loop should outperform the Terk
by 6-10 dB (and blow away anything that fits inside the radio), and
won't require tuning, twisting, major surgery or special battery packs.
73,
Jim, KR1S
_http://kr1s.http://kr1s._ (http://kr1s.kearman.com/)>
I find hanging my loops from the ceiling, over head, is much easier than making 'legs' and finding a spot WITHOUT a radio or speaker in my upstairs room!
-FARMERIK
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:behind what you are doing. My goal would be a simple direct connection,
Jim - I am trying to follow along, but I am unsure of the theory
like the turns on the internal loop coming out through a couple small
holes, and outboard air core loops for AM and LW. It would be much
better for fumble fingered folks like me if the radio just had a jack
when I bought it, but maybe some young enterprising member here could
install the turns on the loop for a fee. The number of turns on the
ferrite need to be matched to the number of turns on the air coil loop
too right? - FARMERIK
I'll try to explain the theory. In a stock PL-300, PL-310 or PL-380, the
ferrite rod serves two functions. It has a coil of about 240 uH
inductance. On MW and LW, this coil is connected in parallel with a
variable capacitor, which is voltage-adjusted. It functions just like
the metal variable capacitors that tune your older radios.
It is a characteristic of the two components, coil and capacitor, that
they can resonate together across the MW band. You can study up on
resonance at Wikipedia or many other sites; what's important to know is
that the coil must resonate with the capacitor at any frequency in the
MW band.
In addition to forming half of a tuned circuit, the ferrite rod also
serves as the MW antenna. If you replace the rod with a coil of the same
inductance wound on a toroid, you still have a tuned circuit, but you
have a poorer antenna, because the toroid forms a closed magnetic field.
I use the terms impedance and reactance, and the differences may be
confusing. If you are interested, it's easy to find books and online
sites that explain these terms. For now, let's say the new coil we have
installed has an impedance at 1000 kHz of 1500 ohms. The impedance of a
coil is directly proportional to its inductance and also directly
proportional to the frequency in use. This is true for all coils. The
impedance ratio between two or more coils remains the same at any
frequency. If Coil A has 1.35 times the impedance of Coil B at Frequency
X, A will have 1.35 times the impedance of B at Frequency Y, Z . . .
Our new antenna, let's say the Hoop Loop, is also a coil. In my case it
has an inductance of 16 uH. At 1000 kHz it has an impedance of 100 ohms.
You obtain the most-efficient transfer of power from one circuit to
another when the impedances are the same. Somehow we have to transform
the 100 ohms of the antenna to the 1500 ohms of the coil.
If we have a transformer with two windings, one of 60 turns and one of
15 turns, we say the turns ratio is 4:1. We know from theory that the
impedance transformation ratio is the square of the turns ratio, so it's
16:1. This gives us the insight needed to calculate the number of turns
on the winding that connects to the Hoop Loop. The square root of the
dividend of 1500 divided by 100 is 3.873. That's our turns ratio. If the
resonant coil has 60 turns, we divide that by 3.873 and round off the
result to 15, the number of turns on the winding that goes to the Hoop
Loop. Because real-world stuff sometimes doesn't exactly match
calculations, we might start with 17 turns and remove one at a time to
get the best signal strength.
Note that the number of turns on the antenna (3) is much different than
the number of turns on the transformer (15). The antenna is wound in
air, while the transformer is wound on a ferrite core. The ferrite core
concentrates the magnetic field, so we can achieve more inductance per
turn than we can in air, but the coil constituting the Hoop Loop is 23
inches in diameter. That's why we use the ferrite toroid (or rod),
instead of making an air-wound transformer, which would be very large
(think of an oatmeal-box crystal-set coil).
(Why not make a higher-impedance Hoop Loop and do away with the
transformer? Two reasons. First, the 23-inch quilting hoop is only
3/4-inch wide. We like to space the turns to reduce self-capacitance,
which limits tuning range, and 3 turns is about right. Also, we'd like
to use cheap, flexible speaker wire as the feed line from antenna to
radio, and it has a characteristic impedance in the range of 50-75 ohms.
We want to match impedances throughout the system as well as possible.)
Thanks to our efforts with a calculator, we now have a resonant antenna
system. It should be obvious that the original ferrite-rod antenna coil
would electrically mimic the toroidal coil with which we replaced it.
But the ferrite rod makes a good antenna, which responds better to
strong signals than we want. We want the signals to come only from the
external antenna. In fact, the chip is so sensitive, even with a tiny
(1/2-inch) toroid, three local stations are still strong with only that
toroidal coil in place! I wrapped some anti-static foil (coated so the
surface is non-conductive and won't short anything in the radio) around
the core to shield it. That helped a little, but the chip is very
sensitive.
I went sideways on this project. At first I only wanted to use the Hoop
Loop for MW. I installed a jack on the side of the radio so I could
disconnect the Hoop Loop for transport. Fitting the jack required
removing the internal antenna and the whip. After a few days I began
wondering how the radio would work if I made a coil that resonated at
LW. Frankly, I didn't expect much, and was very pleasantly surprised to
hear so many European BC stations on what is a very small antenna for
153-279 kHz. (One of Gary's nine-footers with the right number of turns
would be ideal, but then I'd have to eat in the kitchen and watch TV on
the porch.) Fitting a good LW coil inside the box is impossible; they're
too big. As I'm hot for LW, I've re-thought the project to use a larger,
better MW coil (less loss), which will also go outside the box. If all
you want is MW, a smaller coil inside the box (in the spot previously
occupied by the internal antenna) is very adequate. Chris and I proved
that in Melbourne last week.
You can't have it all. These radios are too small. Adding worthwhile
features means giving up something. For what they cost, if you want
excellent desktop performance and a portable, buy two radios! Fit one
for external antennas and re-wind the antenna in the other.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
--- In ultralightdx@..., "farmerik" wrote:
>
>
> Would using 300 ohm or 450 ohm ladder line allow a more turns or a larger loop to match the input on the PL-360? It would have to go through the 1/8th inch plug, but most of the lead could be higher, is it impedance?
I have no experience with the PL-360, but my intuition is that the antenna is 240 uH or thereabouts. That means it appears right across the varactor. Two wires side-by-side have capacitance. I forget the capacitance-per-foot of 300-ohm twinlead but you could look it up. But -- that capacitance will appear in parallel with the tuned circuit, and will increase the minimum tuning capacitance. That will likely prevent the antenna from tuning to the top of the band.
Now, if you used a plug-in transformer and matching winding, yeah I guess you could use twinlead with a higher inductance antenna. But why? When you can use lightweight, flexible, cheap, and readily available speaker wire, why use that heavy, clumsy stuff? Twinlead was invented for use on VHF television. It's a waste on MW. I have 300 feet of it, but I never considered using it for this purpose.
There is no reason to use a higher-inductance antenna. The idea for this project was sparked by the SiLabs datasheet. It mentions using a 5 : 1 turns ratio transformer to accommodate those little AM loop antennas supplied with AM/FM tuners. It turned out that my antenna had a slightly different inductance, so I needed a different turns ratio (3.8 : 1), but the principle is the same.
> I find hanging my loops from the ceiling, over head, is much easier than making 'legs' and finding a spot WITHOUT a radio or speaker in my upstairs room!
Look at the Hoop Loop . The hoop is solidly attached to the base with screws. You could hang it any way you like, without the base, as long as you used non-conductive material like monofilament or mason's string. You'll find stranded speaker wire much friendlier than stiff twinlead if you're rotating a hanging antenna, BTW.
73,
Jim, KR1S
http://kr1s.kearman.com/
I agree with Jim's reasoning and would like to add two more reasons to use a transformer.
1) The transformer provides some galvanic isolation to sensitive components in the radio. The Si4734 AM input is very robust to ESD discharges _for_a_tiny_chip_, but if you bring that input to wires outside the case, more robust ESD protection circuits are highly recommended. If you look inside your radio, you'll see that the FM whip has protection diodes on the PCB to prevent you from zapping the IC inputs.
2) The transformer provides a balanced-to-unbalanced (balun) signal conversion. Without this, the loop sorta looks like two antennas at once: an ideal loop plus a big hunk of wire hanging on a tuned, high-impedance node. This has a tendency to pick up noise and ruin the loop's nulling capabilities. Even the PL-380's internal loopstick is affected a little by this issue.
I once connected a high-Q inductor to the AM input of the Si4734 without the loopstick. I was mainly experimenting with the chip's tuning function, but I noticed that with just the tuned inductor, the radio could pick up several stations. So I connected the high-impedance side of the tank to the FM whip antenna. The resulting signals were huge -- reading over 90 dBuV (PL-300WT)! A loop is not the only way to pick up AM signals. Whips can be excellent too, but don't provide good nulling (with a single whip), and need a good ground and balun to avoid picking up man-made noise.
-Scott-
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:larger loop to match the input on the PL-360? It would have to go
Would using 300 ohm or 450 ohm ladder line allow a more turns or a
through the 1/8th inch plug, but most of the lead could be higher, is it
impedance?
I have no experience with the PL-360, but my intuition is that the
antenna is 240 uH or thereabouts. That means it appears right across the
varactor. Two wires side-by-side have capacitance. I forget the
capacitance-per-foot of 300-ohm twinlead but you could look it up. But
-- that capacitance will appear in parallel with the tuned circuit, and
will increase the minimum tuning capacitance. That will likely prevent
the antenna from tuning to the top of the band.
Now, if you used a plug-in transformer and matching winding, yeah I
guess you could use twinlead with a higher inductance antenna. But why?
When you can use lightweight, flexible, cheap, and readily available
speaker wire, why use that heavy, clumsy stuff? Twinlead was invented
for use on VHF television. It's a waste on MW. I have 300 feet of it,
but I never considered using it for this purpose.
There is no reason to use a higher-inductance antenna. The idea for
this project was sparked by the SiLabs datasheet. It mentions using a 5
: 1 turns ratio transformer to accommodate those little AM loop antennas
supplied with AM/FM tuners. It turned out that my antenna had a slightly
different inductance, so I needed a different turns ratio (3.8 : 1), but
the principle is the same.I find hanging my loops from the ceiling, over head, is much easierthan making 'legs' and finding a spot WITHOUT a radio or speaker in my
upstairs room!
Look at the Hoop Loop <http://kr1s.kearman.com/html/hooploop.html> .
The hoop is solidly attached to the base with screws. You could hang it
any way you like, without the base, as long as you used non-conductive
material like monofilament or mason's string. You'll find stranded
speaker wire much friendlier than stiff twinlead if you're rotating a
hanging antenna, BTW.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
I think Jim mentioned he needs his loop near a window, some distance from where he sits, while I do not need any feedline. I just wondered if he could have a more efficient antenna with the higher impedance twin lead.
It sounds to me that the front end of the chip radios is so sensitive a full size antenna [too big to be practical at AM BCB & LW] would overload it. The 360 model has a plug in ferrite rod antenna on a 1/8th inch telephone plug. ANON offers a package deal with the small tuned Tecsun loop. So I should just try a short wire antenna instead, [if I buy a PL-360], as well as my 2 and 4 foot untuned loops and see what happens. Thanks.
I can read up on the theory, but I wouldn't be confident I wouldn't miss some detail which would ruin my 'experiment'. I am trying to follow the theory though. According to theory my untuned 4 foot loop isn't supposed to work very well since I did not space the windings far enough apart, however, don't tell the radios which like it VERY much. Both the inductance and capacitance of 25 closely wound turns may not allow a cap to tune it, but it is both quiet as far as noise, and yet allows some of my radios to hear far more stations. It does overload others without an RF gain control. - FARMERIK
Jim has lucidly explained several good reasons for using a low inductance loop and transformer (tuning range and flexible wire). The same reasons govern the historical use of low-inductance loops with HiFi receivers. Generally, high-impedance signal inputs like the Si4734 uses are great when the receiver is near the antenna. But lower impedance signals are needed when the antenna is remote from the receiver.
I agree with Jim's reasoning and would like to add two more reasons to use a transformer.
1) The transformer provides some galvanic isolation to sensitive components in the radio. The Si4734 AM input is very robust to ESD discharges _for_a_tiny_chip_, but if you bring that input to wires outside the case, more robust ESD protection circuits are highly recommended. If you look inside your radio, you'll see that the FM whip has protection diodes on the PCB to prevent you from zapping the IC inputs.
2) The transformer provides a balanced-to-unbalanced (balun) signal conversion. Without this, the loop sorta looks like two antennas at once: an ideal loop plus a big hunk of wire hanging on a tuned, high-impedance node. This has a tendency to pick up noise and ruin the loop's nulling capabilities. Even the PL-380's internal loopstick is affected a little by this issue.
I once connected a high-Q inductor to the AM input of the Si4734 without the loopstick. I was mainly experimenting with the chip's tuning function, but I noticed that with just the tuned inductor, the radio could pick up several stations. So I connected the high-impedance side of the tank to the FM whip antenna. The resulting signals were huge -- reading over 90 dBuV (PL-300WT)! A loop is not the only way to pick up AM signals. Whips can be excellent too, but don't provide good nulling (with a single whip), and need a good ground and balun to avoid picking up man-made noise.
-Scott-
--- In ultralightdx@..., "jim_kr1s" <jkearman@> wrote:
--- In ultralightdx@..., "farmerik" <farmerik@> wrote:larger loop to match the input on the PL-360? It would have to go
Would using 300 ohm or 450 ohm ladder line allow a more turns or a
through the 1/8th inch plug, but most of the lead could be higher, is it
impedance?
I have no experience with the PL-360, but my intuition is that the
antenna is 240 uH or thereabouts. That means it appears right across the
varactor. Two wires side-by-side have capacitance. I forget the
capacitance-per-foot of 300-ohm twinlead but you could look it up. But
-- that capacitance will appear in parallel with the tuned circuit, and
will increase the minimum tuning capacitance. That will likely prevent
the antenna from tuning to the top of the band.
Now, if you used a plug-in transformer and matching winding, yeah I
guess you could use twinlead with a higher inductance antenna. But why?
When you can use lightweight, flexible, cheap, and readily available
speaker wire, why use that heavy, clumsy stuff? Twinlead was invented
for use on VHF television. It's a waste on MW. I have 300 feet of it,
but I never considered using it for this purpose.
There is no reason to use a higher-inductance antenna. The idea for
this project was sparked by the SiLabs datasheet. It mentions using a 5
: 1 turns ratio transformer to accommodate those little AM loop antennas
supplied with AM/FM tuners. It turned out that my antenna had a slightly
different inductance, so I needed a different turns ratio (3.8 : 1), but
the principle is the same.I find hanging my loops from the ceiling, over head, is much easierthan making 'legs' and finding a spot WITHOUT a radio or speaker in my
upstairs room!
Look at the Hoop Loop <http://kr1s.kearman.com/html/hooploop.html> .
The hoop is solidly attached to the base with screws. You could hang it
any way you like, without the base, as long as you used non-conductive
material like monofilament or mason's string. You'll find stranded
speaker wire much friendlier than stiff twinlead if you're rotating a
hanging antenna, BTW.
73,
Jim, KR1S
http://kr1s.kearman.com/ <http://kr1s.kearman.com/>
--- In ultralightdx@..., "farmerik" wrote:
> It sounds to me that the front end of the chip radios is so sensitive a full size antenna [too big to be practical at AM BCB & LW] would overload it. The 360 model has a plug in ferrite rod antenna on a 1/8th inch telephone plug. ANON offers a package deal with the small tuned Tecsun loop. So I should just try a short wire antenna instead, [if I buy a PL-360], as well as my 2 and 4 foot untuned loops and see what happens. Thanks.
Perhaps Gary can tell us the inductance of the PL-360's loop antenna. I haven't taken apart the Terk and have never seen the AN-1oo/AN-200 loops. My guess is that the radio can't tune that antenna -- and the antenna already has built-in tuning. So you are going to end up setting the radio on frequency, peaking the antenna, then off-and-on re-tuning the radio. The -360 doesn't appeal to me so I don't want to waste time on it.
> I can read up on the theory, but I wouldn't be confident I wouldn't miss some detail which would ruin my 'experiment'. I am trying to follow the theory though. According to theory my untuned 4 foot loop isn't supposed to work very well
You've hit on an area that arises frequently when discussing radio subjects. Saying "A should work better than B" is absolutely not the same as saying "B won't work very well." How far you go with antennas depends on what you're willing to accept for performance, and how much effort you're willing to expend to improve it. If you think they're "good enough," lucky you! I hope I never reach that point.
73,
Jim, KR1S
http://kr1s.kearman.com/