To: <amps@contesting.com>
>> Date: Wed, 13 May 1998 16:07:51 -0400
>> From: Pete Smith <n4zr@contesting.com>
>> Subject: Re: [AMPS] Re: Parasitics
>> To: amps@contesting.com
>
>> At 11:40 AM 5/13/98 -0800, Rich Measures wrote:
>> >Underloading will not cause a Tune-C arc in my SB-220 or TL-922. The
>> >breakdown potential of a SB-220 Tune-C is c. 3600v, and for the TL-922,
>> >c. 5900v.
>
>and N4ZR Pete replied:
>
>> I have repeatably (not repeatedly, or at least not very often) demonstrated
>> tune-C arcing in my SB-220 in the SSB position. It's an earlier unit, with
>> the narrower-spaced tune-C. In all cases, the arcing happened as a result
>> of underloading, or antenna selection error. I have never experienced
>> arcing when the right antenna was connected and the loading was set just
>> past maximum output. The amplifier is well-constructed and stock except
>> for the Harbach metering/bias board and KM1H's parasitic suppressors.
>> The same errors also produced arcing in a TL-922 I used years ago at 4U1WB,
>> but I can't swear that it was the Tune cap, because you can't see into a
>> TL-922 as well as an SB-220. The amp ran fine throughout an entire WPX CW
>> once I worked out the procedural issues, with never a wiggle.
>
>Rich claimed a K5 had parasitics in his 922 because "mistuning and
>misloading can not cause excess tank voltage or arcs. The K5 showed up
>and correct Rich, and said the nichrome Rich sent him was never
>installed. It turned out the cause of the arc was a bad gas discharge
>tube in his lightning arrester.
Is a bad lightning arrestor breaking down the same thing as deliberate
mistuning?
>
>I think most people understand mistuning or load faults are
>the most common source of arcs in PA's. It is a measurable and
>repeatable event.
>73, Tom W8JI
>w8ji.tom@MCIONE.com
>
>--
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Rich...
R. L. Measures, 805-386-3734, AG6K
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