[Hammarlund] HQ-180 can capacitor

[Gary Pewitt]

Be sure to -completely- disconnect the old can cap when you add the new 
one underneath.



On 11/28/2014 01:01 PM, Robert Sauvan wrote:
>
> 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
>>
>
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