>
>>Hi Jon,
>>I appreciate the response from the reflector.
>>The SB221/220 had the Harbach nichrome suppressor kit installed some
>>years ago, which got rid of arcing I had at that time (although
>>I don't remember where it arced at that time).
>>The TUNE C arcing happens on at least the 10m, 15m and 20m bands.
>>Inspecting the Tune C shows a little black on some of the fins
>>where the arcing has occured.
>
>I would clean this out good. ..
However, if an amplifier is marginally stable, having a Tune-C that arcs
before the bandswitch is Good.
>
>>From original condition, I did the nichrome suppressor kit, added
>>10m (purchased bandswitch and caps/coils input circuit from KM1H),
>>also did the Harbach softstart kit. Recently did the Rich Measures
>>input circuit mods to bring down the input VSWR.
........
>As others have eloquently pointed out, it is possible to make the SB-220
>arc just by mistuning it.
Neither my SB-220 or my TL-922 will arc by mistuning into a 50 ohm
termination.
>.....
>I have suggested measuring the values of the supressor resistors.
amen
>Whether or not they are bad, it is good engineering practice to just do a
sanity
>check on all the components.
yea, verily -- and remember that some types of damage can not be seen.
>It hurts no one to see if everything is
>where it should. If the values are good, then that's great, if bad, then
>you gotta replace them.
>
Replacing them is not as good as finding out how the damage came about.
>Anyhow, the resistors may or may not be your problem. Mis-tuning may be
>your problem instead. ...
My guess is that the amplifier was correctly tuned -- i.e., for maximum
output.
Rich. Measures. Web site: www.vcnet.com/measures
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