Gary DeBock
Hi Stephen,
Thanks for your comments, and I'll try to answer your questions one by
one.
"I don't really care much about any longwave boost (in fact I don't think I
even have anything close to me that would even be detectable WITH a 7.5" Slider
loopstick -- anyone have a suggestion for a website for me to check? btw I'm
within about a mile of 32°46'N 116°57'W), but I do want a sizeable boost on MW
if at all possible. At minimum, I'd like an improvement comparable to what you
got, Gary, on longwave. (I really didn't notice much of a boost on mediumwave in
the examples you posted.) If I could get a boost like the one in the link
below, that would be nice. http://cid-6bdd1917662288cb.skydrive.live.com/self.aspx/AM%20radio%20files/SW20^JSAT%20compare% 20-%20670^ J%20930^J% 20970^J%20980. mp3 That's
my previous radio (Panasonic RQ-SW20), barefoot then with the Select-A-Tenna, on
670, 930, 970 and 980."
Well, Stephen, it would be nice to get an AM sensitivity boost on the
"Stealth PL-380" just like the huge LW enhancement, but trying out any new
loopstick design is something like opening a Christmas present-- the result
could be anything from phenomenal to abominable. My goal in the $5
modification project was simply to achieve a significant boost in AM sensitivity
from 530-1700 kHz, and although the "significant" part is open to
debate, I'm pretty satisfied with the AM results. Someone with more time
could experiment with different Litz wire in attempts to get a greater boost,
but my own impression is that the AM sensitivity in the "Stealth" model is
fairly close to the maximum, when the stock ferrite bar is recycled.
"I'll eventually want to build one of those
several-foot-diameter loops to inductively couple with the PL-380, though.
My Select-A-Tenna just doesn't cut it anymore. Would it be possible, say, with a
6' diameter loop (or should I keep it to 4'?), to have a sizeable boost -- say,
take a signal from completely undetectable on the stock barefoot PL-380 (and
maybe only just barely hetting on Gary's stealth PL-380), to a full 63dBu, 25dB
S/N signal with the loop? Another way to put it, I guess, is with a multi-foot
external loop, I'd want performance comparable to what Bruce Carter (he posts as
rbrucecarter5 on the radio-info.com board) gets with his antennas, or better if
possible"
Stephen, in answer to your question, a 6' sided PVC tuned passive loop
does have the ability to boost the PL-380's AM sensitivity to enable
reception of many DX stations completely inaudible on the barefoot unit, but not
up to the 63 dBu, 25dB level. That level is unnecessary in actual DXing, anyway.
Most of the time the 6' loop will take a station completely inaudible
on the barefoot unit and boost it up to a moderate level, such as this recording
of 1575-Radio Farda here in December: http://www.mediafire.com/?jji22kjj0q1
Radio Farda was completely inaudible on any of the stock Ultralights at the
time. You can use larger loops for better DX signal quality, but none of them
will boost inaudible stations up to the 63 dBu level.
Also, when I do the loopstick mod, I don't have a
(LCR/inductance/?) meter, so anyone have suggestions for how to do it
without one? Also, I understand you usually will check 1700kHz to make sure you
don't get the lockup on the high end of the band with the coil winding. I have a
local on 1700 that is right now (2:10am) showing about 33dBu and 15dB S/N - is
that too strong of a signal already to use as a test signal? Or should I use the
weak TIS from about 15 miles away on 1620 that is next to a semi-local
(comparable signal to 1700, or maybe a bit weaker) on 1630? Or, what about the
one from about 85-95 miles away on 1670 that in the daytime is basically
undetectable most of the time, but at night is about as strong as 1700? (Or,
what about the San Diego Airport TIS on 1690, that even before 1700 was on the
air, was barely detectable on my previous radio even WITH the
Select-A-Tenna?)
"Also, when I do
the loopstick mod, I don't have a (LCR/inductance/?) meter, so anyone have
suggestions for how to do it without one? Also, I understand you usually will
check 1700kHz to make sure you don't get the lockup on the high end of the band
with the coil winding. I have a local on 1700 that is right now (2:10am) showing
about 33dBu and 15dB S/N - is that too strong of a signal already to use as a
test signal? Or should I use the weak TIS from about 15 miles away on 1620 that
is next to a semi-local (comparable signal to 1700, or maybe a bit weaker) on
1630? Or, what about the one from about 85-95 miles away on 1670 that in the
daytime is basically undetectable most of the time, but at night is about as
strong as 1700? (Or, what about the San Diego Airport TIS on 1690, that even
before 1700 was on the air, was barely detectable on my previous radio even WITH
the Select-A-Tenna?)"
Stephen, the loopstick coil turn-subtracting strategy (to solve an
Si4734 varactor lock-up issue on the X-band frequencies) during the PL-380
"Stealth Mod" loopstick tuning was a new method that worked great for me, but
then I don't have any locals around 1700 kHz. I was tuned to that frequency
when subtracting the turns, when suddenly the San Diego (actually Tijuana,
Mexico) station on that frequency boomed in like a local, when I subtracted
the last coil turn. During the entire process I didn't rely on the LCR
meter at all, but I did record the coil inductance after the process was
successful (433 uh). This was done on two different PL-380 "Stealth" models (and
Steve Ratzlaff also presumably used this method, to tune his own modified PL-380
loopstick coil), so the procedure certainly seems to work. If you have
locals around 1700 kHz, go down in frequency until you have "00" showing on the
PL-380's S/N reading, and subtract coil turns one by one until the radio has a
great sensitivity boost on that frequency. Such a strategy will
probably provide adequate coil tuning, but if an LCR meter is available,
simply winding a 40/44 Litz wire coil on the stock ferrite bar for an
inductance of 433 uh should work just as well (assuming that Tecsun and
Silicon Labs don't change anything on us :-)
73, Gary
In a message dated 1/22/2010 2:43:26 A.M. Pacific Standard Time,
pianoplayer88key@... writes:
toggle quoted message
Show quoted text
Ok... lol... seems that this thread kinda got a bit disorganized :) so my
"replies" may be likewise a bit out of order.
So apparently you can use
a ceramic tile saw to cut a ferrite rod. Would it be possible to cut a rod
down its length so I could put a 4" (or 5") Amidon-61 rod in the spot where
the normal loopstick is?
Or, would it be better to consider putting
Eneloop (or other slow-discharge) AAA batteries in the spot where the
loopstick now is, and putting the 5" (after it's cut to size) 0.5" Amidon bar
in the spot where the 2 batteries in line are (while leaving the 3rd AA
there)? Also, considering I don't really want to have to unscrew the back of
the radio every time I need to charge the batteries (normally I pull the dead
set out and put a new one in, then charge the flat ones), is the built-in
charger hardware smart enough to charge those different types of batteries
(different capacity, etc)?
Jim_kr1s, no, I didn't need the heat. :) We
have a wood-burning stove, and before I went to bed (around 5am) the temp on
my PL-380 was showing 70°F.
I just have trouble hearing ANY hets at all -
am I just trying at the wrong time, or using the wrong techniques or
something.... or should I give up on trying to get a TP sandwiched
between a local station's main signal and its IBOC carrier, when that local
station is 63dBu and 25dB S/N?
(Gary Debock:) "Your comments remind me
of the Words of Wisdom a fellow tinkering fanatic shared with me during my
Navy days: "You can do almost anything you want to boost up the performance of
a circuit, depending upon how much time and money you are willing to invest."
:-) Since you have been in the ULR group since the very beginning, no doubt
you have been amazed (and amused) as various innocent Ultralights have had
their IF filters and loopsticks ripped out and discarded, in favor of bizarre
modifications to increase transoceanic reception. Having been the culprit
primarily responsible for this demolition-related activity, I take full
responsibility for my actions."
LOL. :)
I do have a $$ limit
(getting the 7.5" Amidon rod would be a stretch, but a 4" or 6" might be
doable, plus the Litz wire), but I'm much more flexible on time.
I
don't really care much about any longwave boost (in fact I don't think I even
have anything close to me that would even be detectable WITH a 7.5" Slider
loopstick -- anyone have a suggestion for a website for me to check? btw I'm
within about a mile of 32°46'N 116°57'W), but I do want a sizeable boost on MW
if at all possible. At minimum, I'd like an improvement comparable to what you
got, Gary, on longwave. (I really didn't notice much of a boost on mediumwave
in the examples you posted.)
If I could get a boost like the one in the
link below, that would be nice.
http://cid-6bdd1917662288cb.skydrive.live.com/self.aspx/AM%20radio%20files/SW20^JSAT%20compare%20-%20670^J%20930^J%20970^J%20980.mp3
That's
my previous radio (Panasonic RQ-SW20), barefoot then with the Select-A-Tenna,
on 670, 930, 970 and 980.
I'll eventually want to build one of those
several-foot-diameter loops to inductively couple with the PL-380,
though. My Select-A-Tenna just doesn't cut it anymore. Would it be possible,
say, with a 6' diameter loop (or should I keep it to 4'?), to have a sizeable
boost -- say, take a signal from completely undetectable on the stock barefoot
PL-380 (and maybe only just barely hetting on Gary's stealth PL-380), to a
full 63dBu, 25dB S/N signal with the loop? Another way to put it, I guess, is
with a multi-foot external loop, I'd want performance comparable to what Bruce
Carter (he posts as rbrucecarter5 on the radio-info.com board) gets with his
antennas, or better if possible.
Also, when I do the loopstick mod, I
don't have a (LCR/inductance/?) meter, so anyone have suggestions for how
to do it without one? Also, I understand you usually will check 1700kHz to
make sure you don't get the lockup on the high end of the band with the coil
winding. I have a local on 1700 that is right now (2:10am) showing about 33dBu
and 15dB S/N - is that too strong of a signal already to use as a test signal?
Or should I use the weak TIS from about 15 miles away on 1620 that is next to
a semi-local (comparable signal to 1700, or maybe a bit weaker) on 1630? Or,
what about the one from about 85-95 miles away on 1670 that in the daytime is
basically undetectable most of the time, but at night is about as strong as
1700? (Or, what about the San Diego Airport TIS on 1690, that even before 1700
was on the air, was barely detectable on my previous radio even WITH the
Select-A-Tenna?)
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