[Heathkit] Continuing DX-60 Issue

[WQ9E at btsnetworks.net]

Ken,

Are you measuring the final bias voltage key up or key down?  -98 sounds correct key up since the bias should rise to provide protective voltage to the final.  The plate voltage will also rise to a high value key up since the power supply is unloaded at that point.

Did you try the HG-10B again in case the problem is with your Norcal VFO?

Rodger WQ9E

-------- Original Message --------
> From: Ken Miller K6CTW <k6ctw at earthlink.net>
> Sent: Thursday, February 09, 2012 10:36 PM
> To: heathkit at mailman.qth.net
> Subject: [Heathkit] Continuing DX-60 Issue
> 
> All,
> 
> As you have probably surmised, I've been having an issue with the DX-60 I restored and have been running the past couple of years.  Originally, the only issue was that the HG-10B VFO I also restored was not real stable on 20, 15 and 10 (drift).  Thus I built a VFO for it using the NorCal QRP Club's DDS based FCC-1 and FCC-2.  Everything was great and then when changing frequency from the regional net to the Pacific Area Net I heard a click and then the grid current was gone and the plate current was off the scale.
> 
> I did check the oscillator and driver tubes by substituting known good 6CL6's I have in my spares kit.  Unfortunately I do not have a spare 6146 (although that will change here in a couple of days as I ordered some 6146A's).
> 
> Since it didn't appear to be drive that was off, I thought it might have been in the bias circuit.  The voltages I was seeing on the control grid was/is way off (-98 VDC vs the -38 it's supposed to be).  Figuring that it was probably the old electrolytic I decided that the best thing to do was just completely rebuilt the bias circuit.  This was "fun" and made me feel a bit better about having all new and current manufacture parts but to no avail, same thing.  
> 
> While doing that I also noted that the voltage on the Plate was also off by a lot (738 VDC vs the nominal 600 VDC it's supposed to be.  By the way thanks to the nice schematics others on the list have supplied.
> 
> The oscillator and driver voltages seem to be within tolerance.
> 
> Has anyone on the list seen a similar issue?  All suggestions welcome.
> 
> Thanks in advance and 73
> 
> Ken - K6CTW
>