wrote:
On Monday, July 1, 2013 1:49:47 PM UTC-4, wrote:
My restored, aligned GPR-90 is coming home tomorrow - excite to try
the beast on my long wire antenna! Will report later, maybe post a video.

I have owned DX-150s, 160s, Drake R8s, Grundigs, the list goes on and on.
None of those get close to the quality or stability of this GPR-90. Of course,
the thing is so big it is a pain in the ass to locate in the house, but net of
that (maybe I will set it up vertically - would that hurt the tubes in any way?)

Interesting question. This information used to be present in the tube
manuals, some of which, such as the old RCA Receiving Tube Manual, are still
available as reprints. A wild guess would be that it would be the older
tubes, plus the power output tubes, that you would have to worry about.

it is one of if not the best shortwave receiver I have owned. I may keep this
one for a while.

So who made the GPR-90?

George Cornelius wrote:

wrote:
On Monday, July 1, 2013 1:49:47 PM UTC-4, wrote:
My restored, aligned GPR-90 is coming home tomorrow - excite to try
the beast on my long wire antenna! Will report later, maybe post a video.

I have owned DX-150s, 160s, Drake R8s, Grundigs, the list goes on and on.
None of those get close to the quality or stability of this GPR-90. Of course,
the thing is so big it is a pain in the ass to locate in the house, but net of
that (maybe I will set it up vertically - would that hurt the tubes in any way?)

Interesting question. This information used to be present in the tube
manuals, some of which, such as the old RCA Receiving Tube Manual, are still
available as reprints. A wild guess would be that it would be the older
tubes, plus the power output tubes, that you would have to worry about.

it is one of if not the best shortwave receiver I have owned. I may keep this
one for a while.

So who made the GPR-90?


Technical Materiel Corporation

dave wrote:
You forgot to turn on the BFO. BFO level is frequently too low for
demodding SSB hence the need to reduce RF gain.

Yep, easy to see from the jpeg that there's a BFO present.

I seem to remember having to repair an old KnightKit
tube radio that worked OK otherwise - bad capacitor in
the BFO. Person I bought it from didn't know what one
was so he wouldn't have had any reason to know it wasn't
working when he owned it.

On Tue, 2 Jul 2013, dave wrote:


You forgot to turn on the BFO. BFO level is frequently too low for demodding
SSB hence the need to reduce RF gain.

No I didn't. It should be a given that you need the BFO. I was making
the point that it's one of those radios of the time that didn't have a
product detector, so you had to do what all the books said to do. A few
years later, most receivers did have product detectors. Indeed, the
GPR-90 came along right at the cusp, so you could get an external unit
that added a product detector (and I think some extra selectivity) and
some really fine tuning. The receiver has the an IF output jack on the
back, even has a jack for feeding audio back into the receiver (though the
TMC adapter had a built in audio amplifier). Other receivers had similar
units. The R388 and the R390 didn't have product detectors, though they
are considered some of the best receivers from the time (and perhaps for
all time).

But with that level of receiver, turning down RF gain wasn't a real issue.
I had no problem receiving SSB, even on six meters, on the SP-600 I had
forty years ago.

ON the other hand, that Hallicrafters S-120A (the transistorized model)
that I got in the summer of 1971 had a horribly weak BFO, so by the time
I'd attenuated the incoming signal (a pot between the antenna and the
receiver), there weren't many signals left strong enough to receive.

On 07/11/2013 09:38 AM, Michael Black wrote:
On Tue, 2 Jul 2013, dave wrote:


You forgot to turn on the BFO. BFO level is frequently too low for
demodding SSB hence the need to reduce RF gain.

No I didn't. It should be a given that you need the BFO. I was making
the point that it's one of those radios of the time that didn't have a
product detector, so you had to do what all the books said to do. A few
years later, most receivers did have product detectors. Indeed, the
GPR-90 came along right at the cusp, so you could get an external unit
that added a product detector (and I think some extra selectivity) and
some really fine tuning. The receiver has the an IF output jack on the
back, even has a jack for feeding audio back into the receiver (though
the TMC adapter had a built in audio amplifier). Other receivers had
similar units. The R388 and the R390 didn't have product detectors,
though they are considered some of the best receivers from the time (and
perhaps for all time).

But with that level of receiver, turning down RF gain wasn't a real
issue. I had no problem receiving SSB, even on six meters, on the SP-600
I had forty years ago.

ON the other hand, that Hallicrafters S-120A (the transistorized model)
that I got in the summer of 1971 had a horribly weak BFO, so by the time
I'd attenuated the incoming signal (a pot between the antenna and the
receiver), there weren't many signals left strong enough to receive.


I've had a couple R-390As. I used to leave them on 11175 upper with RF
gain low, carrier sliced off with 2 or 4 KC mechanical filter by
slightly tuning off center, BFO on about 1200 cycles. It was dead quiet
unless someone spoke, like dolby FM. It would stay perfectly tuned for
days, with the ovens off.

I can't afford electricity to waste on old radios.

On Wed, 3 Jul 2013, Brenda Dyer wrote:



"Michael Black" wrote in message
news:alpine.LNX.2.02.1307021228560.22267@darkstar. example.org...

I'm sure by your CB handle I've been licensed longer than you, since June
of 1872, and the test was a lot harder here in Canada since it wasn't
aimed at the beginner.

Michael


--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

Please, share your secret for such longevity. You must have learned code
directly from Samuel F.B. Morse.


Sorry about that. It had to be 1972, since until April of that year, you
had to be fifteen or older to get a ham license in Canada. I've never
been able to find out if that rule had been there from the beginning or
had been added at some later point.

When I first read about amateur radio, I'm not sure if it was in Jack &
Jill magazine or a magazine for scouting here in Canada, I can't remember
whether I was 8 or 9. But right from that point it was something I
wanted, but I knew right at that point that I had some years to wait.
Then in December of 1971, I'd been a member of the ARRL since April of
that year, I read in the paper that the rule about age was being removed.
It turned out to come into effect only in April. In May I took the test,
failed at receiving code, then took the code test again (we didn't have to
take the whole test over) in June, and passed. So if I wasn't the
youngest ham at the time, I had to be among the youngest, not much time
for someone younger to take the test.

Michael

dave wrote:

On 07/11/2013 09:38 AM, Michael Black wrote:
On Tue, 2 Jul 2013, dave wrote:


You forgot to turn on the BFO. BFO level is frequently too low for
demodding SSB hence the need to reduce RF gain.

No I didn't. It should be a given that you need the BFO. I was making
the point that it's one of those radios of the time that didn't have a
product detector, so you had to do what all the books said to do. A few
years later, most receivers did have product detectors. Indeed, the
GPR-90 came along right at the cusp, so you could get an external unit
that added a product detector (and I think some extra selectivity) and
some really fine tuning. The receiver has the an IF output jack on the
back, even has a jack for feeding audio back into the receiver (though
the TMC adapter had a built in audio amplifier). Other receivers had
similar units. The R388 and the R390 didn't have product detectors,
though they are considered some of the best receivers from the time (and
perhaps for all time).

But with that level of receiver, turning down RF gain wasn't a real
issue. I had no problem receiving SSB, even on six meters, on the SP-600
I had forty years ago.

ON the other hand, that Hallicrafters S-120A (the transistorized model)
that I got in the summer of 1971 had a horribly weak BFO, so by the time
I'd attenuated the incoming signal (a pot between the antenna and the
receiver), there weren't many signals left strong enough to receive.


I've had a couple R-390As. I used to leave them on 11175 upper with RF
gain low, carrier sliced off with 2 or 4 KC mechanical filter by
slightly tuning off center, BFO on about 1200 cycles. It was dead quiet
unless someone spoke, like dolby FM. It would stay perfectly tuned for
days, with the ovens off.

I can't afford electricity to waste on old radios.

Yeah, after all, your pal, Boy Barry, said that under his plan, electricity
costs would necessarily skyrocket.

You're both f00kin clown 'tards!

On Thursday, July 11, 2013 5:48:55 PM UTC-5, dxAce wrote:
dave wrote:



On 07/11/2013 09:38 AM, Michael Black wrote:

On Tue, 2 Jul 2013, dave wrote:





You forgot to turn on the BFO. BFO level is frequently too low for

demodding SSB hence the need to reduce RF gain.



No I didn't. It should be a given that you need the BFO. I was making

the point that it's one of those radios of the time that didn't have a

product detector, so you had to do what all the books said to do. A few

years later, most receivers did have product detectors. Indeed, the

GPR-90 came along right at the cusp, so you could get an external unit

that added a product detector (and I think some extra selectivity) and

some really fine tuning. The receiver has the an IF output jack on the

back, even has a jack for feeding audio back into the receiver (though

the TMC adapter had a built in audio amplifier). Other receivers had

similar units. The R388 and the R390 didn't have product detectors,

though they are considered some of the best receivers from the time (and

perhaps for all time).



But with that level of receiver, turning down RF gain wasn't a real

issue. I had no problem receiving SSB, even on six meters, on the SP-600

I had forty years ago.



ON the other hand, that Hallicrafters S-120A (the transistorized model)

that I got in the summer of 1971 had a horribly weak BFO, so by the time

I'd attenuated the incoming signal (a pot between the antenna and the

receiver), there weren't many signals left strong enough to receive.





I've had a couple R-390As. I used to leave them on 11175 upper with RF

gain low, carrier sliced off with 2 or 4 KC mechanical filter by

slightly tuning off center, BFO on about 1200 cycles. It was dead quiet

unless someone spoke, like dolby FM. It would stay perfectly tuned for

days, with the ovens off.



I can't afford electricity to waste on old radios.



Yeah, after all, your pal, Boy Barry, said that under his plan, electricity

costs would necessarily skyrocket.



You're both f00kin clown 'tards!

Back on that sauce again, Tonto?

On Thursday, July 11, 2013 12:41:11 PM UTC-4, dave wrote:
On 07/11/2013 09:38 AM, Michael Black wrote:

On Tue, 2 Jul 2013, dave wrote:





You forgot to turn on the BFO. BFO level is frequently too low for

demodding SSB hence the need to reduce RF gain.



No I didn't. It should be a given that you need the BFO. I was making

the point that it's one of those radios of the time that didn't have a

product detector, so you had to do what all the books said to do. A few

years later, most receivers did have product detectors. Indeed, the

GPR-90 came along right at the cusp, so you could get an external unit

that added a product detector (and I think some extra selectivity) and

some really fine tuning. The receiver has the an IF output jack on the

back, even has a jack for feeding audio back into the receiver (though

the TMC adapter had a built in audio amplifier). Other receivers had

similar units. The R388 and the R390 didn't have product detectors,

though they are considered some of the best receivers from the time (and

perhaps for all time).



But with that level of receiver, turning down RF gain wasn't a real

issue. I had no problem receiving SSB, even on six meters, on the SP-600

I had forty years ago.



ON the other hand, that Hallicrafters S-120A (the transistorized model)

that I got in the summer of 1971 had a horribly weak BFO, so by the time

I'd attenuated the incoming signal (a pot between the antenna and the

receiver), there weren't many signals left strong enough to receive.





I've had a couple R-390As. I used to leave them on 11175 upper with RF

gain low, carrier sliced off with 2 or 4 KC mechanical filter by

slightly tuning off center, BFO on about 1200 cycles. It was dead quiet

unless someone spoke, like dolby FM. It would stay perfectly tuned for

days, with the ovens off.



I can't afford electricity to waste on old radios.

My R-390(not A)got drowned in seawater last year, during the storm called Sandy . Now I don't know what to do with it...

On Fri, 12 Jul 2013, wrote:


My R-390(not A)got drowned in seawater last year, during
the storm called Sandy . Now I don't know what to do with it...

It's kind of late now. You should have carefuly rinsed it out at the
time, getting into all the crevices, then let it dry carefully, usually by
putting it in the oven at a very low temperature for some hours.

Every so often the ham magazines would run articles about what to do with
equipment that fell into even salt water. I think Glen Zook did a piece in
CQ in the early seventies, that did deal with something as complicated as
the R390.

I once dragged home a stereo receiver that I found in a bank of snow, it
was suffering from some minor salt damage due to salt used for melting
ice. I rinsed it carefully and then popped it in the oven, and that got
rid of the salt, it ran for years.

Michael