The 4 bypass caps down by the plate choke have been known to go and I always
replace that little "VHF" choke with a 10-15 Ohm 20W real wirewound.
Another common failure point is the bandswitch at the wafers to support
screw on the right hand side. On 160 it will arc from the solder terminal,
thru the nylon washer to the support screw. If they look OK I give that area
on both wafers a good coat of Q Dope (liquid polystyrene). Never tried
Corona Dope, dont know its RF ratings.
Another nasty spot is the cheap steel tube clips, they rust bad on the
inside.
Alpha wants $300 per wafer but it is only $250 or so for a complete switch
thru Mouser. I just got thru with a 76PA complete switch meltdown 2 weeks
ago for a customer. A 76PA is also my 2nd station amp which I obtained as a
meltdown in more than just the switch.
Carl
KM1H
----- Original Message -----
From: "Robert Harmon" <k6uj@pacbell.net>
To: "Carl" <km1h@jeremy.mv.com>
Cc: <amps@contesting.com>
Sent: Sunday, March 13, 2011 3:00 PM
Subject: Re: [Amps] doorknob cap suppliers ?
Carl,
Yes that is what is in there, two 2000pf 6kv discs in parallel.
I'm going through and upgrading caps in the amp, already replaced the
electrolytic filter caps in the power supply,
thought I might upgrade these two disc ceramics while I was at it.
It makes sense to replace old electrolytics but these two disc ceramics look
just fine, maybe I should just leave them alone.
(They just don't look beefy enough with their little twisted together wire
leads, hi,hi)
Bob
K6UJ
On Mar 13, 2011, at 10:22 AM, Carl wrote:
> The 76 family uses two 2000pf 6KV discs in parallel. If they look like the
> wax has boiled out I replace with 3 1000pf 6KV discs but Ive never found
> one yet that shows leakage at even 3000V.
>
> Carl
> KM1H
>
>
> ----- Original Message ----- From: "Robert Harmon" <k6uj@pacbell.net>
> To: <amps@contesting.com>
> Sent: Sunday, March 13, 2011 10:20 AM
> Subject: [Amps] doorknob cap suppliers ?
>
>
>> I am upgrading my Alpha 76CA plate capacitors and I'm looking for two
>> 2000pf doorknob caps
>> to replace the two pig tail caps. Found used ones at RF parts. MGS
>> doesn't show any of this value on their site,
>> Found exactly what I want on the HEC home page for new ones but can't
>> find a supplier.
>> Any recommendations on suppliers ?
>>
>> thanks,
>> Bob
>> K6UJ
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
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