[Amps] AL-80A "spitting" on 80m, Relay problems.

[R.Measures]

On Sep 14, 2005, at 8:06 PM, Bill Coleman wrote:

>
> On Sep 12, 2005, at 10:32 PM, Tom Rauch wrote:
>
>> The spitting is either a bad part like a bad or burnt plate
>> on a capacitor, misaligned relay contacts (the load contact
>> should mechanically close slightly before the input contact)
>> , or you have it loaded too lightly on 80. Sounds like it is
>> loaded too lightly. Open the load control up more.
>
> I resolved the "spitting" problem. After carefully tuning up the amp
> for 80m, using as little loading C as possible to get the maximum
> output, there was no spitting into the dummy load. Then I switched it
> over to my doublet, which is fed through a Murch UT-2000A tuner.
>
> Then I got the spitting, even though the tuner was tuned up for a
> good match. A little detective work revealed that the spitting sound
> was coming from the tuner, not the amp.
>
> Taking the cover off the tuner revealed that there was intermittent
> arcing across both the load and tune cap, favoring the load cap
> first. After blowing the dust and other particles out of the case,
> and off the capacitor plates -- still arcs.
>
> It's really curious that a tuner rated for 2 kW arcs so easily at
> just 600 watts of CW.

Bill -- What is the length of air gap that is arcing?
>
> Jury is still out on the relay problem. I'll have to work on that.
>
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Quote: "Not within a thousand years will man ever fly!"
>              -- Wilbur Wright, 1901
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org