I'm not sure if this is 'homebrew' exactly, but close enough, maybe..

I was looking around via Google, but found allusions to rather than direct
sources, of an internal modification to allow the unused middle connector of
the antenna socket to allow an external AM antenna. I've not found the
article itself, or any pointer saying exactly where it is either. All I have
is a name, Laurie Mann, in Australia.

I'd already tried coupling a long wire directly to the AM input after
unsoldering the wire on tne non-grounded end of the winding on the ferrite
rod, with no meaningful improvement (as expected, it worked, but was too
noisy to be helpful in any way). While a car radio will take any bit of wire
as an antenna the PL-390's AM isn't meant to work that way. I'd already tried
doing that with the winding still soldered in place too, with no convincing
result.

If anyone's worked on this particular radio to improve AM, especially by neat
internal work like a rewound ferrite rod (because apparently the Si4734 DSP
Radio IC will take a wide range of inductance), I'm interested to hear about
it. Also, any other useful modifications...

Last but not least, I'm not so sure that its AM performance on long wave is
as bad as is often claimed. Maybe it's just not as excellent as much of the
rest of the radio, but as an example of LW reception I have this:
On Ashton Court, just over the Somerset border south west of Bristol, 48
miles away from Southampton, I picked up an NDB transmission 'EAS'. I did not
know it existed beforehand, but heard it well enough after several minutes to
note its code unambiguously so I could look it up after returning home. That
NDB has a nominal range of only 15 nautical miles, and what is worse, it has
to compete on 391.5KHz with Cardiff on 388.5 KHz. Cardiff is very strong, and
very close. Worse yet, its bearing is W, and Southampton's is ESE, so it's
not like I can use the orientation of the radio to help a lot. Despite
this, using the 1KHz filter which DID help a lot, I could select the
ghostlike distant EAS signal while completely excluding CDF. On any other
filter, CDF blasts all over it, and the AR-3000 at home was utterly helpless
with its 8 metre high vertical whip. Sensitive, sure, but about as selective
as the aim of a blunderbuss.

In short, I think the Tecsun PL-390's LW AM performance is a LOT better than
it is credited for generally, but all the same I'd like to have a crack at
seeing if I can hear an NDB from london to Bristol. I know, little things
please little minds. But it's a very fun way to learn so I want to have at
it, and I'm interested in anything anyone has to say if they have worked on
modifying this specific radio in any way.

On Sat, 6 Sep 2014, Lostgallifreyan wrote:

I'm not sure if this is 'homebrew' exactly, but close enough, maybe..

I was looking around via Google, but found allusions to rather than direct
sources, of an internal modification to allow the unused middle connector of
the antenna socket to allow an external AM antenna. I've not found the
article itself, or any pointer saying exactly where it is either. All I have
is a name, Laurie Mann, in Australia.

I'd already tried coupling a long wire directly to the AM input after
unsoldering the wire on tne non-grounded end of the winding on the ferrite
rod, with no meaningful improvement (as expected, it worked, but was too
noisy to be helpful in any way). While a car radio will take any bit of wire
as an antenna the PL-390's AM isn't meant to work that way. I'd already tried
doing that with the winding still soldered in place too, with no convincing
result.

IN the old days, they'd either suggest wrapping some wire around the
radio, grounding one side and the other going to the antenna. In other
words, a inductive coupling loop to the loopstick. The advantage of this
method is that it requires no modification, the disadvantage is that it
looks messy and may interfere with the controls.

So you open up the radio and put a few turns on the loopstick, grounding
one end and the other going to the antenna. It's the same thing, but no
messy outside loop (and in the case of a digitally tuned radio, winding
directly on the loopstick likely adds less noise than a winding around the
radio (which might pick up the noise from the radio).

It does make me wonder what is done in the average shortwave portable.
EIther the external antenna connector doesn't work on the AM broadcast and
LW bands, or they use some other scheme to couple to the rest of the
receiver on those bands. I don't have that sort of schematic handy.

The internal loopstick needs to stay as it is, since it's not just "an
antenna", but the tuned circuit at the front of the radio. Unless you
were going to get really fancy, and change the loopstick for a shielded
coil fo the same inductance, and then coupled the antenna to that.

Or, use a big external loop of the same inductance, and use that instead
of the internal loop, though in that case, it won't be so portable, and
you wouldn't want to have the loop any distance from the radio.



In short, I think the Tecsun PL-390's LW AM performance is a LOT better
than it is credited for generally, but all the same I'd like to have a
crack at seeing if I can hear an NDB from london to Bristol. I know,
little things please little minds. But it's a very fun way to learn
so I want to have at it, and I'm interested in anything anyone has to
say if they have worked on modifying this specific radio in any way.

The only reviews I've seen of that sort of radio are from here in North
America. An important consideration is that there is no long wave
broadcasting over here, so the LW band is mostly dead. The only thing
left down there is some airport beacons. I havent' spent much time tuing
LW, but all I've heard is the local airport beacon (and maybe the Ottawa
beacon, I wasn't completely sure). That was with a Grundig YB400,
shrotwave portables are the only LW receivers I've ever had.

But if you live in the land of LW broadcasting, that might change the
comments about the LW band being "dead", since it may not be the receiver,
but the lack of transmitters.

I have a Grundig/Eton G8 and I've not heard anything on the LW band, but
maybe I wasn't doing it right.

Michael

Michael Black wrote in
news:alpine.LNX.2.02.1409062303070.10573@darkstar. example.org:

IN the old days, they'd either suggest wrapping some wire around the
radio, grounding one side and the other going to the antenna. In other
words, a inductive coupling loop to the loopstick. The advantage of this
method is that it requires no modification, the disadvantage is that it
looks messy and may interfere with the controls.

So you open up the radio and put a few turns on the loopstick, grounding
one end and the other going to the antenna. It's the same thing, but no
messy outside loop (and in the case of a digitally tuned radio, winding
directly on the loopstick likely adds less noise than a winding around the
radio (which might pick up the noise from the radio).


Thankyou! I liked that idea so much I went without sleep and had at it. I
have no photo hosting but I'm willing to upload a picture of the doings if
there's a way to make it generally useful.

I now have a little over 100 turns of enamelled copper wire (a thickness
chosen to allow good current for lowest loss) on one end of the PL-390's
ferrite bar. One end is grounded, the other, after laying two layers of turns
around the rod in the same direction as the main winding, is soldered to the
unused middle connection of the 3.5mm RF input jack. The result is excellent
too, despite the huge amounts of ambient noise from computer, router, modem,
LCD touchscreen and all, I'm getting every NDB I have detected with the
single exception of the ghostly Southhampton 15nm range one. I thought I'd
lost Gloucestershire too but apparently it has changed frequency a tad, and
it's definitely there, clear if not strong. Once I get a chance to run a
longwire out on Ashton Court I think I might hear London Calling... (Good
album, that though I prefer X-Ray Spex. Never mind, long story...)

Anyway, this is in the city centre, close to sea level, using the 8m tall
external whip. I think once I get it tested out on open land 125m above sea
level with a longwire it will be a great deal more interesting than it was
out there before.

It does make me wonder what is done in the average shortwave portable.
EIther the external antenna connector doesn't work on the AM broadcast and
LW bands, or they use some other scheme to couple to the rest of the
receiver on those bands. I don't have that sort of schematic handy.


The PL-390 does it by switching the local telescopic whip out of circuit when
the remote antenna jack is plugged in. The unused middle terminals would be
equally capable of this, but they're soldered together and I left them that
way, other than adding my own wire from the new coil. Neither the whip or the
external antenna socket are used by the AM wavebands (MW+LW with a remarkably
small gap where the emergency shipping signals used to be at around 500 KHz).
I think there are two separate inputs to the DSP IC, one for these AM bands,
and another for HF and VHF. It might be even more complex, but I don't know.
I want to avoid taking the radio apart any more than I did, it's extremely
fragile...

The internal loopstick needs to stay as it is, since it's not just "an
antenna", but the tuned circuit at the front of the radio. Unless you
were going to get really fancy, and change the loopstick for a shielded
coil fo the same inductance, and then coupled the antenna to that.


Agreed. The shielded inductor is a nice idea, but the first idea is best for
me, as it does not compromise intended operation in any way all, but adds a
great deal to the PL-390's AM capability. Whether more or less turns than my
100 (approx..) would be better I'm not sure but I didn't see any signs of
overload when checking the Bristol airport NDB, and either it's not at all
critical, or I got lucky. What IS critical is a good ground...

Or, use a big external loop of the same inductance, and use that instead
of the internal loop, though in that case, it won't be so portable, and
you wouldn't want to have the loop any distance from the radio.


I think that's what the people discussing the Laurie Mann modification were
doing, but I didn't get enough of the original context to be sure. One guy
was certainly doing something with a 4' loop built using 1.5'' UPVC pipe. Not
as portable as I want. It could be great if I want to explore external
tuning though. (And a good excuse to use some very nice tuning capacitors.)
My original plan was to try a larger ferrite rod and coil, something more
like the multi-layered turns I've seen on old receivers, but tonight's work
has left me satisfied for now, and likely for some time, it will take several
attempts to figure out how far it will go.



In short, I think the Tecsun PL-390's LW AM performance is a LOT better
than it is credited for generally, but all the same I'd like to have a
crack at seeing if I can hear an NDB from london to Bristol. I know,
little things please little minds. But it's a very fun way to learn
so I want to have at it, and I'm interested in anything anyone has to
say if they have worked on modifying this specific radio in any way.

The only reviews I've seen of that sort of radio are from here in North
America. An important consideration is that there is no long wave
broadcasting over here, so the LW band is mostly dead. The only thing
left down there is some airport beacons. I havent' spent much time tuing
LW, but all I've heard is the local airport beacon (and maybe the Ottawa
beacon, I wasn't completely sure). That was with a Grundig YB400,
shrotwave portables are the only LW receivers I've ever had.


Apparently there are submarines, but only at around 30 KHz. Things are
allegedly better for US LW DX if you can get to an ocean. I read a web page
that suggested it might be more exciting than I can know. Having lots of LW
transmissions isn't the boon it might seem, the big ones swamp the band so
much the allocation is pretty much one per nation in Europe, though France
has three! Maybe you also get something I know of here but have not explored,
there's some kind of digital modulation at around 100 KHz (carrier) for
logistical stuff for roads and weather, for hauliers and such. Also MSF time
at 60 KHz but that's beyond any receiver I've had for a long time.

By the way, my dad had a Grundig Yacht Boy 210, an ancestor of your YB400. I
identified with it more closely than if it had been a family pet. It was
central to home life, we had no TV... Got to say I liked the Hacker radios
better though, for general listening. I intend to make a cabinet to mount
the PL-390, for home use, better sound, larger NiMH cells, etc. Sonically,
it's surprisingly close to hi-fi on VHF. I think it just might be the best
all-rounder receiver ever designed for mass marketing and low cost.

On 07/09/14 19:06, Lostgallifreyan wrote:
Once I get a chance to run a
longwire out on Ashton Court I think I might hear London Calling... (Good
album, that though I prefer X-Ray Spex. Never mind, long story...)

Great, now I've got that song in my head. (And yes, I've got that album
on LP too.) I see I'll be giving that song and a few others on that
album a flogging when I get to work tomorrow.

Still, good to hear you've got your set suitably modified and working.
Not sure if that set does SSB (doesn't look like it) but it looks like a
handy little receiver.

On 07/09/14 10:06, Lostgallifreyan wrote:
Michael Black wrote in
news:alpine.LNX.2.02.1409062303070.10573@darkstar. example.org:

IN the old days, they'd either suggest wrapping some wire around the
radio, grounding one side and the other going to the antenna. In other
words, a inductive coupling loop to the loopstick. The advantage of this
method is that it requires no modification, the disadvantage is that it
looks messy and may interfere with the controls.

So you open up the radio and put a few turns on the loopstick, grounding
one end and the other going to the antenna. It's the same thing, but no
messy outside loop (and in the case of a digitally tuned radio, winding
directly on the loopstick likely adds less noise than a winding around the
radio (which might pick up the noise from the radio).


Thankyou! I liked that idea so much I went without sleep and had at it. I
have no photo hosting but I'm willing to upload a picture of the doings if
there's a way to make it generally useful.

I now have a little over 100 turns of enamelled copper wire (a thickness
chosen to allow good current for lowest loss) on one end of the PL-390's
ferrite bar. One end is grounded, the other, after laying two layers of turns
around the rod in the same direction as the main winding, is soldered to the
unused middle connection of the 3.5mm RF input jack. The result is excellent
too, despite the huge amounts of ambient noise from computer, router, modem,
LCD touchscreen and all, I'm getting every NDB I have detected with the
single exception of the ghostly Southhampton 15nm range one. I thought I'd
lost Gloucestershire too but apparently it has changed frequency a tad, and
it's definitely there, clear if not strong. Once I get a chance to run a
longwire out on Ashton Court I think I might hear London Calling... (Good
album, that though I prefer X-Ray Spex. Never mind, long story...)

Anyway, this is in the city centre, close to sea level, using the 8m tall
external whip. I think once I get it tested out on open land 125m above sea
level with a longwire it will be a great deal more interesting than it was
out there before.

It does make me wonder what is done in the average shortwave portable.
EIther the external antenna connector doesn't work on the AM broadcast and
LW bands, or they use some other scheme to couple to the rest of the
receiver on those bands. I don't have that sort of schematic handy.


The PL-390 does it by switching the local telescopic whip out of circuit when
the remote antenna jack is plugged in. The unused middle terminals would be
equally capable of this, but they're soldered together and I left them that
way, other than adding my own wire from the new coil. Neither the whip or the
external antenna socket are used by the AM wavebands (MW+LW with a remarkably
small gap where the emergency shipping signals used to be at around 500 KHz).
I think there are two separate inputs to the DSP IC, one for these AM bands,
and another for HF and VHF. It might be even more complex, but I don't know.
I want to avoid taking the radio apart any more than I did, it's extremely
fragile...

The internal loopstick needs to stay as it is, since it's not just "an
antenna", but the tuned circuit at the front of the radio. Unless you
were going to get really fancy, and change the loopstick for a shielded
coil fo the same inductance, and then coupled the antenna to that.


Agreed. The shielded inductor is a nice idea, but the first idea is best for
me, as it does not compromise intended operation in any way all, but adds a
great deal to the PL-390's AM capability. Whether more or less turns than my
100 (approx..) would be better I'm not sure but I didn't see any signs of
overload when checking the Bristol airport NDB, and either it's not at all
critical, or I got lucky. What IS critical is a good ground...

Or, use a big external loop of the same inductance, and use that instead
of the internal loop, though in that case, it won't be so portable, and
you wouldn't want to have the loop any distance from the radio.


I think that's what the people discussing the Laurie Mann modification were
doing, but I didn't get enough of the original context to be sure. One guy
was certainly doing something with a 4' loop built using 1.5'' UPVC pipe. Not
as portable as I want. It could be great if I want to explore external
tuning though. (And a good excuse to use some very nice tuning capacitors.)
My original plan was to try a larger ferrite rod and coil, something more
like the multi-layered turns I've seen on old receivers, but tonight's work
has left me satisfied for now, and likely for some time, it will take several
attempts to figure out how far it will go.



In short, I think the Tecsun PL-390's LW AM performance is a LOT better
than it is credited for generally, but all the same I'd like to have a
crack at seeing if I can hear an NDB from london to Bristol. I know,
little things please little minds. But it's a very fun way to learn
so I want to have at it, and I'm interested in anything anyone has to
say if they have worked on modifying this specific radio in any way.

The only reviews I've seen of that sort of radio are from here in North
America. An important consideration is that there is no long wave
broadcasting over here, so the LW band is mostly dead. The only thing
left down there is some airport beacons. I havent' spent much time tuing
LW, but all I've heard is the local airport beacon (and maybe the Ottawa
beacon, I wasn't completely sure). That was with a Grundig YB400,
shrotwave portables are the only LW receivers I've ever had.


Apparently there are submarines, but only at around 30 KHz. Things are
allegedly better for US LW DX if you can get to an ocean. I read a web page
that suggested it might be more exciting than I can know. Having lots of LW
transmissions isn't the boon it might seem, the big ones swamp the band so
much the allocation is pretty much one per nation in Europe, though France
has three! Maybe you also get something I know of here but have not explored,
there's some kind of digital modulation at around 100 KHz (carrier) for
logistical stuff for roads and weather, for hauliers and such. Also MSF time
at 60 KHz but that's beyond any receiver I've had for a long time.

By the way, my dad had a Grundig Yacht Boy 210, an ancestor of your YB400. I
identified with it more closely than if it had been a family pet. It was
central to home life, we had no TV... Got to say I liked the Hacker radios
better though, for general listening. I intend to make a cabinet to mount
the PL-390, for home use, better sound, larger NiMH cells, etc. Sonically,
it's surprisingly close to hi-fi on VHF. I think it just might be the best
all-rounder receiver ever designed for mass marketing and low cost.

=============
Talking LW time signals ,the UK MSF 60kHz tx is now located at Anthorn
-Cumbria . Sig here in Scotland is pretty strong.
It is a bit different with DCF at 77 KHz located near Frankfurt a/M
-Germany .
Both Lidl and Aldi (supermarkets) sell radio controlled clocks on 77KHz,
but to get the radio time signal I have to place such a clock near the
window here in the north of Scotland (IO87AT)
A reliable signal seems to be available everywhere up to approx 1000 kms
from the tx
Do you receive DCF ,77 khz well on your rx ?

Frank , GM0CSZ

Frank GM0CSZ

Stuart Longland wrote in news:dnntdb-
:

On 07/09/14 19:06, Lostgallifreyan wrote:
Once I get a chance to run a
longwire out on Ashton Court I think I might hear London Calling... (Good
album, that though I prefer X-Ray Spex. Never mind, long story...)

Great, now I've got that song in my head. (And yes, I've got that album
on LP too.) I see I'll be giving that song and a few others on that
album a flogging when I get to work tomorrow.

Still, good to hear you've got your set suitably modified and working.
Not sure if that set does SSB (doesn't look like it) but it looks like a
handy little receiver.


Thanks. No, no USB, or CW, though it may be possible to add a local
oscollator externally to recover some of that, but I don't know enough to
make suggestions about how.

highlandham wrote in news:lui1dh$ku0$1@dont-
email.me:

Talking LW time signals ,the UK MSF 60kHz tx is now located at Anthorn
-Cumbria . Sig here in Scotland is pretty strong.
It is a bit different with DCF at 77 KHz located near Frankfurt a/M
-Germany .
Both Lidl and Aldi (supermarkets) sell radio controlled clocks on 77KHz,
but to get the radio time signal I have to place such a clock near the
window here in the north of Scotland (IO87AT)
A reliable signal seems to be available everywhere up to approx 1000 kms
from the tx
Do you receive DCF ,77 khz well on your rx ?


I wish I could.. Neither of my radios will do it. 100KHz on the AOR AR-3000
is as low as it gets here. Maybe some frequency doubling relay can exist that
would allow down to 50 KHz reception...

Over a decade ago when I was looking at MSF based on a Maplin kit or two, the
transmissions were still from somewhere further south than now, not sure
where, they'd just changed from Rugby a few years earlier. Teddington maybe?
Reception was awkward, very fussy inside a basement, but it worked.

There's an Ultralite group on Yahoo. They do a lot with cobbling in
loops, etc to such radios. I haven't checked-in in a long time since
back when I had a PL-380. They have tallied up some good results as a
group are knowledgeable about the tuning system in that series or radios.

-Bill

Bill M wrote in :

There's an Ultralite group on Yahoo. They do a lot with cobbling in
loops, etc to such radios. I haven't checked-in in a long time since
back when I had a PL-380. They have tallied up some good results as a
group are knowledgeable about the tuning system in that series or radios.


I think they might be the source of what I found. I used to have access to
Yahoo until BT changed the login for emails to their own hosts. Right now I
doubt I have access, and Yahoo insist on policing me to use the latest
browser to access their walled garden (and by default and direct follow-on)
the latest Windows OS too, to support it! All this to access what is
basically a text discussion with a bit of picture hosting.

Now, if any of them read this and are willing to post on Usenet which is a
much better medium for the subject, I'm totally content.

The alternative is to do without as a result of my stand in not yielding to
the fabricated urge that drives so many people to accept systems aimed at
satisfying those who do not know anything about simple efficiency, at the
expense of all those who do. I could live with that, but I'd rather encourage
people to use Usenet. It's obituaries grow many and old, while it continues
to thrive.

Lostgallifreyan wrote:
Bill M wrote in :

There's an Ultralite group on Yahoo. They do a lot with cobbling in
loops, etc to such radios. I haven't checked-in in a long time since
back when I had a PL-380. They have tallied up some good results as a
group are knowledgeable about the tuning system in that series or radios.


I think they might be the source of what I found. I used to have access to
Yahoo until BT changed the login for emails to their own hosts. Right now I
doubt I have access, and Yahoo insist on policing me to use the latest
browser to access their walled garden (and by default and direct follow-on)
the latest Windows OS too, to support it! All this to access what is
basically a text discussion with a bit of picture hosting.

Now, if any of them read this and are willing to post on Usenet which is a
much better medium for the subject, I'm totally content.

The alternative is to do without as a result of my stand in not yielding to
the fabricated urge that drives so many people to accept systems aimed at
satisfying those who do not know anything about simple efficiency, at the
expense of all those who do. I could live with that, but I'd rather encourage
people to use Usenet. It's obituaries grow many and old, while it continues
to thrive.

Ohhh. That's quite a conundrum my friend.
An alternative might be to contact Jim Kearman, KR1S, over on the Radio
Board Forum. He's a ringmaster with the Ultralights and I'm sure would
be happy to share his insights.

http://theradioboard.com/rb/index.php

I'll save my comments on the demise of Usenet.

-Bill