[Heathkit] HG-10 -VFO power supply, DX-60B

[RJ Mattson]

I never found one specific to Heath, but there are a number of published T-R 
circuits that are tied between the PA plate and the pi-network. Since they 
share the pi-net filter, any harmonics are attenuated and afford the rcvr 
additional bandpass selectivity. I am using one with my Hammarlund Four20 
xmtr/HQ-129x for full break-in CW. The xmtr keying needs to supply some sort 
of muting like rf gain reduction or your rcvr will overload like you 
mention. Although not harmful it is unbearable in volume :-) My grid block 
vfo keying circuitry also supplies gain reducing bias to the HQ-129x to have 
comfortable CW monitoring tone with key down.
The Heath HW-16 rx/tx employs a variation of this method.
Merry Christmas,
bob...w2ami
http://www.qrz.com/callsign/w2ami

> Also, this DX-60B has an electronic T-R switch
> modification in  it. This involves an added tube, and
> was described in a QST article. I  could never really
> use the T-R switch, though, because the transmitter
> signal  still got through to the receiver so strong it
> was scary. Anybody familiar with  this modification?
>