[Hammarlund] HQ-180 can capacitor

[Robert Sauvan]

I believe my next step will be to replace the can capacitor. Hayseed has 
them for $35.00 or so but I have some electrolytics that can be mounted 
under the chassis. I know the diehards would just go for the replacement 
can cap but I can do that later. I think I will try the electrolytics I 
have and see what happens. As I have been tuning the bands this morning, 
I am noticing the SSB signals are a bit distorted as well. All I have, 
to compare the sound of this unit, is my HQ-170A. I would assume the 2 
radios should sound fairly similar. If that seems to care care of the 
problem Im done. If not, I will dig into the AVC circuitry again.Will 
let you know what comes out of this.

Thanks-Bob-W0YBS


On 11/28/2014 11:26 AM, Richard Knoppow wrote:
>
> ----- Original Message ----- From: "Robert Sauvan" <rsauvan at beyondbb.com>
> To: "Hammarlund Mail List" <hammarlund at mailman.qth.net>
> Sent: Friday, November 28, 2014 6:09 AM
> Subject: [Hammarlund] HQ-180 can capacitor
>
>
>> Hi all,
>> I had been working on my HQ-180 replacing this and that and doing a 
>> complete alignment. It works fine (better than ever) but I still feel 
>> I have distorted cw signals somewhat. I had posted this previously 
>> and most pointed to the AVC section of the circuits but I have not 
>> located anything amiss there.  I am curious to know whether or not 
>> the possibility of one of the caps in my can capacitor might be 
>> causing the issue. I always noticed that there was a large 
>> electrolytic mounted under the chassis that I thought looked a bit 
>> out of place. After digging into it a bit more, It became obvious it 
>> was replacing one of the can capacitors. So, this got me to thinking 
>> that maybe the can cap is starting to slowly fail and therefore 
>> possibly this is my issue with the distorted cw signals. SSB signals 
>> sound good. I have made a bunch of resistance and voltage 
>> measurements (except at this can cap area) but have not found a spot 
>> that is looking really bad. So, any ideas?
>>
>> Thanks-Bob-W0YBS
>
>     The quickest way to check a cap is to replace it. Don't bridge 
> another across it because if its leaky that will make no difference.
>     Bad filter caps cause all sorts of problems without necessarily 
> increasing hum a lot. For instance, one of my SP-600s began to have 
> very bad spurious signals, this turned out to be one of the filter 
> caps. Also check any cap associated with the AVC, the bypass caps must 
> have good performance because AVC circuits are usuall rather high 
> impedance so it doesn't take much leakage to upset them.
>     Its likely Hayseed Hamfest has direct replacements for the 
> original can cap.
>
>
> -- 
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>