Hello All,
My apologies if this mod has already appeared in the forum.

I recently purchased the PL-310 and, eager to try out some of Gary DeBock's ferrite loopstick ideas, I popped the back off and I noticed, happily, that the 3.5 mm socket for the ext SW/FM antenna is actually a stereo switched socket and that the SW-FM switched connection for the whip antenna is directed to go to the tip of a 3.5 mm stereo plug. The other pair of switched terminals in the socket are for the ring connection to a stereo plug and are conveniently left unconnected on the PCB. Hence I routed the internal loop stick hot connection through these unused terminals so that with no plug in the socket the internal ferrite rod is connected as normal and, when a 3.5 mm stereo plug is connected, the internal ferrite rod is disconnected and the MW/LW input circuit of the radio is available on the ring connection of the plug. The only thing to watch for is potential shorts between the whip antenna base and these pads on the PCB as they are almost coincident with one anoth er when the back of the radio is in place; I put insulating tape over the base of the whip where it overlaps these pads and there has been no shorting problems thus far.

Via this plug connection made with a short length (few inches) of RG-174 coax, I tried large external loop sticks around 2,000 uH and they work very well on LW being tuned by the radio's internal cap up to about 400 kHz. For an external MW ferrite rod it is necessary to avoid too much stray capacitance for the upper end of the band if you want the radio's internal cap to tune the ferrite coil, or else optimise with a lower coil inductance than you might otherwise use. A switched inductance coil on the external ferrite rod will doubtlessly be the way to go but the stray C in the interconnect to the radio will be an issue and I may end up going with short open leads to the 3.5 mm plug to allow minimum stray capacitance.

The mod also allows for the direct connection of external tuned loops and my external amplified tuned MW/LW ferrite rods work very well through this interface.

Regards from Perth, Western Australia
Laurie Mann

Hello All,
My apologies if this mod has already appeared in the forum.

I recently purchased the PL-310 and, eager to try out some of Gary DeBock's ferrite loopstick ideas, I popped the back off and I noticed, happily, that the 3.5 mm socket for the ext SW/FM antenna is actually a stereo switched socket and that the SW-FM switched connection for the whip antenna is directed to go to the tip of a 3.5 mm stereo plug. The other pair of switched terminals in the socket are for the ring connection to a stereo plug and are conveniently left unconnected on the PCB. Hence I routed the internal loop stick hot connection through these unused terminals so that with no plug in the socket the internal ferrite rod is connected as normal and, when a 3.5 mm stereo plug is connected, the internal ferrite rod is disconnected and the MW/LW input circuit of the radio is available on the ring connection of the plug. The only thing to watch for is potential shorts between the whip antenna base and these pads on the PCB as they are almost coincident with one another when the back of the radio is in place; I put insulating tape over the base of the whip where it overlaps these pads and there has been no shorting problems thus far.

Via this plug connection made with a short length (few inches) of RG-174 coax, I tried large external loop sticks around 2,000 uH and they work very well on LW being tuned by the radio's internal cap up to about 400 kHz. For an external MW ferrite rod it is necessary to avoid too much stray capacitance for the upper end of the band if you want the radio's internal cap to tune the ferrite coil, or else optimise with a lower coil inductance than you might otherwise use. A switched inductance coil on the external ferrite rod will doubtlessly be the way to go but the stray C in the interconnect to the radio will be an issue and I may end up going with short open leads to the 3.5 mm plug to allow minimum stray capacitance.

The mod also allows for the direct connection of external tuned loops and my external amplified tuned MW/LW ferrite rods work very well through this interface.

Regards from Perth, Western Australia
Laurie Mann

Hello Laurie (and Byron),

Congratulations on your simple and highly effective modification of
rewiring the PL-310's external antenna plug-in jack, to allow highly sensitive MW
and LW antennas of all types to be used in boosting the PL-310's
performance, Laurie. That's one of the best ULR modification ideas I've seen
recently, and certainly one that should prove extremely popular!

Because most of my own LW and MW 7.5" loopstick experimentation has been
concentrated on the PL-380 model, I had no option but to design a similar
plug-in "docking port" for the top of the PL-380 cabinet, which would accept
the 7.5" plug-in MW loopsticks already sent out to 22 DXers using the PL-360
model. This is certainly a more involved process than rewiring an existing
plug-in jack, as in your PL-310 modification. For those DXers wishing to
use the PL-310 with any type of external LW or MW plug-in antenna, your
modification is certainly the way to go!

Regarding the avoidance of high AM-band varactor lockup (in the Si4734
chip) when transplanting loopsticks, I did run extensive tests with various
coil inductances and orientations in the 7.5" loopstick PL-380 model, using a
signal generator under controlled conditions. The results may be of
interest to you in your PL-310 loopstick experimentation, Laurie, and are posted
at _http://www.mediafire.com/?jwdqmdzmi0j_
(http://www.mediafire.com/?jwdqmdzmi0j) . Thanks again for sharing the details of your highly effective
modification, and we all appreciate your experimental success in
transforming the PL-310 into a very effective DX receiver.

73 and Best Wishes,
Gary DeBock (in Puyallup, WA, USA)


In a message dated 8/14/2010 9:32:05 A.M. Pacific Daylight Time,
lmann98@... writes:




Hello All,
My apologies if this mod has already appeared in the forum.

I recently purchased the PL-310 and, eager to try out some of Gary
DeBock's ferrite loopstick ideas, I popped the back off and I noticed, happily,
that the 3.5 mm socket for the ext SW/FM antenna is actually a stereo
switched socket and that the SW-FM switched connection for the whip antenna is
directed to go to the tip of a 3.5 mm stereo plug. The other pair of switched
terminals in the socket are for the ring connection to a stereo plug and are
conveniently left unconnected on the PCB. Hence I routed the internal loop
stick hot connection through these unused terminals so that with no plug
in the socket the internal ferrite rod is connected as normal and, when a
3.5 mm stereo plug is connected, the internal ferrite rod is disconnected and
the MW/LW input circuit of the radio is available on the ring connection
of the plug. The only thing to watch for is potential shorts between the
whip antenna base and these pads on the PCB as they are almost coincident with
one anoth er when the back of the radio is in place; I put insulating tape
over the base of the whip where it overlaps these pads and there has been
no shorting problems thus far.

Via this plug connection made with a short length (few inches) of RG-174
coax, I tried large external loop sticks around 2,000 uH and they work very
well on LW being tuned by the radio's internal cap up to about 400 kHz. For
an external MW ferrite rod it is necessary to avoid too much stray
capacitance for the upper end of the band if you want the radio's internal cap to
tune the ferrite coil, or else optimise with a lower coil inductance than
you might otherwise use. A switched inductance coil on the external ferrite
rod will doubtlessly be the way to go but the stray C in the interconnect
to the radio will be an issue and I may end up going with short open leads
to the 3.5 mm plug to allow minimum stray capacitance.

The mod also allows for the direct connection of external tuned loops and
my external amplified tuned MW/LW ferrite rods work very well through this
interface.

Regards from Perth, Western Australia
Laurie Mann

 

Gary - could you remember to check if the antenna jack on the new PL-210 also works on AM and/or LW ? - THAT would make it very interesting for those unable to do tiny modifications. - FARMERIK

--- In ultralightdx@..., D1028Gary@... wrote:
>
> Hello Laurie (and Byron),
>
> Congratulations on your simple and highly effective modification of
> rewiring the PL-310's external antenna plug-in jack, to allow highly sensitive MW
> and LW antennas of all types to be used in boosting the PL-310's
> performance, Laurie. That's one of the best ULR modification ideas I've seen
> recently, and certainly one that should prove extremely popular!
>
> Because most of my own LW and MW 7.5" loopstick experimentation has been
> concentrated on the PL-380 model, I had no option but to design a similar
> plug-in "docking port" for the top of the PL-380 cabinet, which would accept
> the 7.5" plug-in MW loopsticks already sent out to 22 DXers using the PL-360
> model. This is certainly a more involved process than rewiring an existing
> plug-in jack, as in your PL-310 modification. For those DXers wishing to
> use the PL-310 with any type of external LW or MW plug-in antenna, your
> modification is certainly the way to go!
>
> Regarding the avoidance of high AM-band varactor lockup (in the Si4734
> chip) when transplanting loopsticks, I did run extensive tests with various
> coil inductances and orientations in the 7.5" loopstick PL-380 model, using a
> signal generator under controlled conditions. The results may be of
> interest to you in your PL-310 loopstick experimentation, Laurie, and are posted
> at _http://www.mediafire.com/?jwdqmdzmi0j_
> (http://www.mediafire.com/?jwdqmdzmi0j) . Thanks again for sharing the details of your highly effective
> modification, and we all appreciate your experimental success in
> transforming the PL-310 into a very effective DX receiver.
>
> 73 and Best Wishes,
> Gary DeBock (in Puyallup, WA, USA)
>
>
> In a message dated 8/14/2010 9:32:05 A.M. Pacific Daylight Time,
> lmann98@... writes:
>
>
>
>
> Hello All,
> My apologies if this mod has already appeared in the forum.
>
> I recently purchased the PL-310 and, eager to try out some of Gary
> DeBock's ferrite loopstick ideas, I popped the back off and I noticed, happily,
> that the 3.5 mm socket for the ext SW/FM antenna is actually a stereo
> switched socket and that the SW-FM switched connection for the whip antenna is
> directed to go to the tip of a 3.5 mm stereo plug. The other pair of switched
> terminals in the socket are for the ring connection to a stereo plug and are
> conveniently left unconnected on the PCB. Hence I routed the internal loop
> stick hot connection through these unused terminals so that with no plug
> in the socket the internal ferrite rod is connected as normal and, when a
> 3.5 mm stereo plug is connected, the internal ferrite rod is disconnected and
> the MW/LW input circuit of the radio is available on the ring connection
> of the plug. The only thing to watch for is potential shorts between the
> whip antenna base and these pads on the PCB as they are almost coincident with
> one anoth er when the back of the radio is in place; I put insulating tape
> over the base of the whip where it overlaps these pads and there has been
> no shorting problems thus far.
>
> Via this plug connection made with a short length (few inches) of RG-174
> coax, I tried large external loop sticks around 2,000 uH and they work very
> well on LW being tuned by the radio's internal cap up to about 400 kHz. For
> an external MW ferrite rod it is necessary to avoid too much stray
> capacitance for the upper end of the band if you want the radio's internal cap to
> tune the ferrite coil, or else optimise with a lower coil inductance than
> you might otherwise use. A switched inductance coil on the external ferrite
> rod will doubtlessly be the way to go but the stray C in the interconnect
> to the radio will be an issue and I may end up going with short open leads
> to the 3.5 mm plug to allow minimum stray capacitance.
>
> The mod also allows for the direct connection of external tuned loops and
> my external amplified tuned MW/LW ferrite rods work very well through this
> interface.
>
> Regards from Perth, Western Australia
> Laurie Mann
>

Hello All,
My apologies if this mod has already appeared in the forum.

I recently purchased the PL-310 and, eager to try out some of Gary
DeBock's ferrite loopstick ideas, I popped the back off and I noticed,
happily, that the 3.5 mm socket for the ext SW/FM antenna is actually a
stereo switched socket and that the SW-FM switched connection for the whip
antenna is directed to go to the tip of a 3.5 mm stereo plug. The other
pair of switched terminals in the socket are for the ring connection to a
stereo plug and are conveniently left unconnected on the PCB. Hence I
routed the internal loop stick hot connection through these unused
terminals so that with no plug in the socket the internal ferrite rod is
connected as normal and, when a 3.5 mm stereo plug is connected, the
internal ferrite rod is disconnected and the MW/LW input circuit of the
radio is available on the ring connection of the plug. The only thing to
watch for is potential shorts between the whip antenna base and these pads
on the PCB as they are almost coincident with one another when the back of
the radio is in place; I put insulating tape over the base of the whip
where it overlaps these pads and there has been no shorting problems thus
far.

Via this plug connection made with a short length (few inches) of RG-174
coax, I tried large external loop sticks around 2,000 uH and they work
very well on LW being tuned by the radio's internal cap up to about 400
kHz. For an external MW ferrite rod it is necessary to avoid too much
stray capacitance for the upper end of the band if you want the radio's
internal cap to tune the ferrite coil, or else optimise with a lower coil
inductance than you might otherwise use. A switched inductance coil on
the external ferrite rod will doubtlessly be the way to go but the stray C
in the interconnect to the radio will be an issue and I may end up going
with short open leads to the 3.5 mm plug to allow minimum stray
capacitance.

The mod also allows for the direct connection of external tuned loops and
my external amplified tuned MW/LW ferrite rods work very well through this
interface.

Regards from Perth, Western Australia
Laurie Mann

Hi Laurie:

If/when you get a chance, some photos of your handiwork would be much
appreciated! I have no particular talent for soldering, but this might be
something I could try, and photos of how it looks before/after would be
helpful. Feel free to post them here on the Group

Kevin S
Bainbridge Island, WA

Hello All,
My apologies if this mod has already appeared in the forum.

I recently purchased the PL-310 and, eager to try out some of Gary
DeBock's ferrite loopstick ideas, I popped the back off and I noticed,
happily, that the 3.5 mm socket for the ext SW/FM antenna is actually a
stereo switched socket and that the SW-FM switched connection for the whip
antenna is directed to go to the tip of a 3.5 mm stereo plug. The other
pair of switched terminals in the socket are for the ring connection to a
stereo plug and are conveniently left unconnected on the PCB. Hence I
routed the internal loop stick hot connection through these unused
terminals so that with no plug in the socket the internal ferrite rod is
connected as normal and, when a 3.5 mm stereo plug is connected, the
internal ferrite rod is disconnected and the MW/LW input circuit of the
radio is available on the ring connection of the plug. The only thing to
watch for is potential shorts between the whip antenna base and these pads
on the PCB as they are almost coincident with one another when the back of
the radio is in place; I put insulating tape over the base of the whip
where it overlaps these pads and there has been no shorting problems thus
far.

Via this plug connection made with a short length (few inches) of RG-174
coax, I tried large external loop sticks around 2,000 uH and they work
very well on LW being tuned by the radio's internal cap up to about 400
kHz. For an external MW ferrite rod it is necessary to avoid too much
stray capacitance for the upper end of the band if you want the radio's
internal cap to tune the ferrite coil, or else optimise with a lower coil
inductance than you might otherwise use. A switched inductance coil on
the external ferrite rod will doubtlessly be the way to go but the stray C
in the interconnect to the radio will be an issue and I may end up going
with short open leads to the 3.5 mm plug to allow minimum stray
capacitance.

The mod also allows for the direct connection of external tuned loops and
my external amplified tuned MW/LW ferrite rods work very well through this
interface.

Regards from Perth, Western Australia
Laurie Mann

Hello Laurie,

Many thanks for posting your mod for the PL-310. That external antenna
connector was what caused me to buy a '310 from anon-co last week. It
was shipped on 8/12 and now I have a mod to immediately perform. At the
time I ordered it, my interest was mainly for Moxon antennas on the FM
band. I see the '310 uses that same loop stick configuration as the
'380. I took mine out, rewound it with 40/44 litz wire and put it back
in. I have a 280uH crate loop that I'll plug into it when it arrives.
Your mod, and Tecsun's unused connectors, sure make antenna
experimentation easier.

Is it my eyes or is the ferrite bar in the pictures of your '310
slightly rounded on the horizontal length?

Rick W4DST

Hello Laurie,

Many thanks for posting your mod for the PL-310. That external antenna
connector was what caused me to buy a '310 from anon-co last week. It
was shipped on 8/12 and now I have a mod to immediately perform. At the
time I ordered it, my interest was mainly for Moxon antennas on the FM
band. I see the '310 uses that same loop stick configuration as the
'380. I took mine out, rewound it with 40/44 litz wire and put it back
in. I have a 280uH crate loop that I'll plug into it when it arrives.
Your mod, and Tecsun's unused connectors, sure make antenna
experimentation easier.

Is it my eyes or is the ferrite bar in the pictures of your '310
slightly rounded on the horizontal length?

Rick W4DST

Hello Rick and Kevin,

Thank you, you're welcome. Rick, you are correct; the ferrite rod in my PL-310 is indeed warped along its length by probably 5-10 degrees and means that it won't sit flat in the recess for which it was designed. That's not unusual in my experience with cheap ferrite rods. Fortunately Amidon stock doesn't suffer this problem.

Best regards,
Laurie Mann
Perth, Western Australia

--- In ultralightdx@..., Rick Robinson <w4dst@> wrote:

Hello Laurie,

Many thanks for posting your mod for the PL-310. That external antenna
connector was what caused me to buy a '310 from anon-co last week. It
was shipped on 8/12 and now I have a mod to immediately perform. At the
time I ordered it, my interest was mainly for Moxon antennas on the FM
band. I see the '310 uses that same loop stick configuration as the
'380. I took mine out, rewound it with 40/44 litz wire and put it back
in. I have a 280uH crate loop that I'll plug into it when it arrives.
Your mod, and Tecsun's unused connectors, sure make antenna
experimentation easier.

Is it my eyes or is the ferrite bar in the pictures of your '310
slightly rounded on the horizontal length?

Rick W4DST

----- Original Message -----

From: bgcpa54

To: ultralightdx@...

Sent: Wednesday, August 18, 2010 3:39 PM

Subject: [ultralightdx] Re: PL-310 external MW/LW antenna connection

 

Laurie,

I would dearly love to see your PL-310 external antenna mod, however, yahoo tells me the file is unavailable when I click on the link. Do you have any ideas or could you be so kind to email me the file directly at bgcpa54@...?

Thanks,

Barry Gelb
Bayside, NY

Laurie,
Like Barry I cannot access your file either so I too would appreciate a look at it direct,
at your leisure of course.
Thank you,
Brian, G0NSL-QRP.
brian.nsl@...
----- Original Message -----
From: bgcpa54
To: ultralightdx@...
Sent: Wednesday, August 18, 2010 3:39 PM
Subject: [ultralightdx] Re: PL-310 external MW/LW antenna connection



Laurie,

I would dearly love to see your PL-310 external antenna mod, however, yahoo tells me the file is unavailable when I click on the link. Do you have any ideas or could you be so kind to email me the file directly at bgcpa54@...?

Thanks,

Barry Gelb
Bayside, NY

 

Hi Gary

I made some experiments with ferrite rod antennas for MW and have read your work with the ultralight receivers and I'm really impressed with all research and results achieved in this field.

I have one doubt related to the position of the coil, as I see you position it in one edge of the rod, not the center.

I have been trying both configurations (not direct coupled to the receiver, always by magnetically coupling) and I have observed that inductance varies of course, but performance is best when the coil is in the center position.

Is there big signal variation or nulling capacity in this position using the coil directly coupled?

Regards,

Sarmento

--- In ultralightdx@..., D1028Gary@... wrote:
>
> Hello Laurie (and Byron),
>
> Congratulations on your simple and highly effective modification of
> rewiring the PL-310's external antenna plug-in jack, to allow highly sensitive MW
> and LW antennas of all types to be used in boosting the PL-310's
> performance, Laurie. That's one of the best ULR modification ideas I've seen
> recently, and certainly one that should prove extremely popular!
>
> Because most of my own LW and MW 7.5" loopstick experimentation has been
> concentrated on the PL-380 model, I had no option but to design a similar
> plug-in "docking port" for the top of the PL-380 cabinet, which would accept
> the 7.5" plug-in MW loopsticks already sent out to 22 DXers using the PL-360
> model. This is certainly a more involved p rocess than rewiring an existing
> plug-in jack, as in your PL-310 modification. For those DXers wishing to
> use the PL-310 with any type of external LW or MW plug-in antenna, your
> modification is certainly the way to go!
>
> Regarding the avoidance of high AM-band varactor lockup (in the Si4734
> chip) when transplanting loopsticks, I did run extensive tests with various
> coil inductances and orientations in the 7.5" loopstick PL-380 model, using a
> signal generator under controlled conditions. The results may be of
> interest to you in your PL-310 loopstick experimentation, Laurie, and are posted
> at _http://www.mediafire.com/?jwdqmdzmi0j_
> (http://www.mediafire.com/?jwdqmdzmi0j) . Thanks again for sharing the details of your highly effective
> modification, and we all appreciate your experimental success in
> transforming the PL-310 into a very effective DX recei ver.
>
> 73 and Best Wishes,
> Gary DeBock (in Puyallup, WA, USA)
>
>
> In a message dated 8/14/2010 9:32:05 A.M. Pacific Daylight Time,
> lmann98@... writes:
>
>
>
>
> Hello All,
> My apologies if this mod has already appeared in the forum.
>
> I recently purchased the PL-310 and, eager to try out some of Gary
> DeBock's ferrite loopstick ideas, I popped the back off and I noticed, happily,
> that the 3.5 mm socket for the ext SW/FM antenna is actually a stereo
> switched socket and that the SW-FM switched connection for the whip antenna is
> directed to go to the tip of a 3.5 mm stereo plug. The other pair of switched
> terminals in the socket are for the ring connection to a stereo plug and are
> conveniently left unconnected on the PCB. Hence I routed the internal loop
> stick hot connection through these unu sed terminals so that with no plug
> in the socket the internal ferrite rod is connected as normal and, when a
> 3.5 mm stereo plug is connected, the internal ferrite rod is disconnected and
> the MW/LW input circuit of the radio is available on the ring connection
> of the plug. The only thing to watch for is potential shorts between the
> whip antenna base and these pads on the PCB as they are almost coincident with
> one anoth er when the back of the radio is in place; I put insulating tape
> over the base of the whip where it overlaps these pads and there has been
> no shorting problems thus far.
>
> Via this plug connection made with a short length (few inches) of RG-174
> coax, I tried large external loop sticks around 2,000 uH and they work very
> well on LW being tuned by the radio's internal cap up to about 400 kHz. For
> an external MW ferrite rod it is necessary to avoid too much stray
> capacitance for the upper end of the band if you want the radio's internal cap to
> tune the ferrite coil, or else optimise with a lower coil inductance than
> you might otherwise use. A switched inductance coil on the external ferrite
> rod will doubtlessly be the way to go but the stray C in the interconnect
> to the radio will be an issue and I may end up going with short open leads
> to the 3.5 mm plug to allow minimum stray capacitance.
>
> The mod also allows for the direct connection of external tuned loops and
> my external amplified tuned MW/LW ferrite rods work very well through this
> interface.
>
> Regards from Perth, Western Australia
> Laurie Mann
>