[AMPS] Parasitic suppressors/another question,

[km1h@juno.com]

On Sat, 10 Apr 1999 09:53:10 -0400 "Dick Green" <dick.green@valley.net>
writes:
>
>W5AH wrote:
>
>> In the 220s Ive worked on with bandswitch damage that damage
>can be directly attributed to the operator rotating the band switch
>instead of the load control while tuning up.  The physical layout
>of the tune, load and bandswitch controls makes it easy to turn
>the wrong knob and cause the "parasitic" damage.
>
>Yes! It's about time somebody brought that up. I can't count the times 
>I've
>reached for the wrong knob on that amp. Luckily, I've never turned it 
>far
>enough to break contact, but I can see how that could happen easily in 
>the
>heat of a contest. There really is not that much difference in 
>mechanical
>resistance between the Load and Band knobs, so you don't get much 
>physical
>feedback before it's too late.
>
>Seems to me that we have reasonable alternate explanations for all of 
>the
>symptoms attributed to parasitics in the SB-220:
>
>1. Burned-out band switches caused by accidentally turning the band 
>switch
>while tuning.
>2. Cooked suppressor resistors caused by pushing the amp to the max 
>(1200W
>CW @SSB position).
>3. Arcing at the Tune capacitor by over rotation of the Load capacitor 
>(easy
>to do.)
>
>Hmmm. Operator error in all three cases. What a surprise. Are there 
>any
>others we can add to the list?

4. Gradual loss of tension in the contacts over time and QRO.

73  Carl  KM1H


>
>Thanks for your post, Bob.
>
>73, Dick, WC1M
>
>
>
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