[Hammarlund] Re-Capping HQ-180A - Some Questions

[Kenneth G. Gordon]

On 13 Jul 2019 at 14:33, Steve Reed wrote:

> Hi all -- I've got a HQ-180A here and and started the re-capping process.
> The replacement power supply filter capacitor that I ordered from
> Hayseedhamfest is rated: 65-45-45 (at 450v) and then there's a fourth pin
> on the can rated 45mfd at 50v.  The ACTUAL filter capacitor on my HQ-180A,
> however, is rated 80-40-20 (450v) and there is no fourth pin.

Hmmm....that must be an early '180...

>  To add to
> the confusion (and just to make it hard for me to trace a lot of this out),
> the only manual I have for a HQ-180A identifies the filter capacitor (C82),
> as a 60-40-40-40 at 450v.

No. That voltage rating is wrong. It MAY BE what is shown on the can, but according to the 
schematic diagrams and the parts lists I have here, that cap is C-82A, 60 MFD at 400 VDC, 
C-82B, 40 MFD at 400 VDC, C-82C, 40 MFD at 350 VDC, and C-82D 40 MFD at 25 VDC.

Also, remember that those old caps were speced at something like +20%/-100%, so the 
Hayseed cap should work perfectly in that service.

>  So this is wandering all over the place.  So, a
> couple of questions:
> 1 - Is that Hayseedhamfest cap a direct replacement regardless of the
> difference in the ratings?

Pretty much so, yes.

> 2 - Does anyone have a schematic for the version of the HQ-180A I have?  I
> realize there were many different production versions.

Well, I have two schematics on different '180As here, both have the 4 section cap listed, 
and none have a 3 section cap.

In almost every receiver I have dealt with in the past 63 years, that fourth pin and cap is the 
cathode bypass cap for the audio output stage.

Your receiver MAY have a separate individual cap for that purpose. You will have to 
examine the receiver closely around the audio output stage (6AQ5?) to see if there is an 
electrolytic cap of around 25 to 50 MFD connected from the cathode, pin 2, to ground.

Usually, these caps are rated at something like 25 to 50 VDC and 25 to 50 MFD.

Ken W7EKB