Heathkit SW-717 receiver
 

Hi, everyone,
I picked up a Heathkit short wave transistorized radio, model SW-717,
"series no" 08731, at a garage sale this W/E - not working well, some
reception on BC bands but low sensitivity. I put a few low level sig.
gen. RF signals on the antenna terminal, from 1 MHz to about 12 MHz
but reception spotty and not to dial scale.

My guess is that it is 1970's vintage, perhaps a bit before. It has 9
transistors (2 power types); no integrated circuits; cannot find any
IFT's (very odd!) but there are a total of 7 unshielded coils on the
PCB. It has a 2 gang tuning capacitor with one gang of lower
capacitance than the other with 10 plates vs. 11, about 390/500 pF in
size - suggests an oscillator to me, i.e. not a TRF set.

I've not yet done a full forensics yet in case I can save time by
looking at the schematic. Will pay for copying and mailing costs for
a manual, or the original, or would appreciate even just a scan of
schematic by email to:
'surfnews "at" sprint "dot" ca' suitably written, of course..

All info on this model will be greatly appreciated. Many thanks for
all replies,

Cheers,

Roger

"Engineer" wrote in message
...

My guess is that it is 1970's vintage, perhaps a bit before.

Circa '74

It has 9
transistors (2 power types); no integrated circuits; cannot find any
IFT's (very odd!) but there are a total of 7 unshielded coils on the
PCB. It has a 2 gang tuning capacitor with one gang of lower
capacitance than the other with 10 plates vs. 11, about 390/500 pF in
size - suggests an oscillator to me, i.e. not a TRF set.

It was a simple superhet. I think the IFT's may've been little ceramic
types? It's *so* long ago...
Front end was a 40673 MOSFET. The audio quality of the rx was very nice, but
of course meant selectivity was poor. Also the AGC was pathetic, it
overloaded very easily. The audio stage was prone to microphony, a damping
cicruit across the speaker helps.

HTH
Gary

"Gary" .uk wrote in
message ...

"Engineer" wrote in message
...

My guess is that it is 1970's vintage, perhaps a bit before.

Circa '74

It has 9
transistors (2 power types); no integrated circuits; cannot find
any
IFT's (very odd!) but there are a total of 7 unshielded coils on
the
PCB. It has a 2 gang tuning capacitor with one gang of lower
capacitance than the other with 10 plates vs. 11, about 390/500 pF
in
size - suggests an oscillator to me, i.e. not a TRF set.

It was a simple superhet. I think the IFT's may've been little
ceramic
types? It's *so* long ago...
Front end was a 40673 MOSFET. The audio quality of the rx was very
nice, but
of course meant selectivity was poor. Also the AGC was pathetic, it
overloaded very easily. The audio stage was prone to microphony, a
damping
cicruit across the speaker helps.

HTH
Gary

Many thanks, Gary. I'll see what I can do with it.

Cheers,

Roger