On Sat, 10 Oct 1998 21:54:23 +0100 Pete Smith <n4zr@contesting.com>
writes:
>
>At 08:18 AM 10/10/98 -0800, Rich Measures wrote:
>...
>
>>perhaps. Increased R is more likely.
>>
>>>He's going to tell me wether or not they are. It's just another
>feather
>in your cap
>>
>>? nice pun, Jon. congrats
>>
>>>on your theory!
>>>
>>F. E. Handy wrote about it in 1926
>>. (Radio Amateur's Handbook).
>>G. W. Fyler wrote about it in Sept. 1935
>>. (IRE Proceedings)
>>H. F Dittrich wrote about it in the 50s.
>> . (*Tubes for R. F. Heating*)
>>
>>I am but a Richy come lately.
>
>There's only one problem with all this mutual admiration
Mutual something anyway Pete.............
there is
>insufficient data to indicate any parasitic at all, since the writer
>didn't
>tell us whether the arcing occurred on one band or all, and didn't
>specify
>the loading condition. I can make my SB-220 arc on demand -- I don't
>do it
>any more -- with drastically too-light loading on some antennas.
If you "try" you can even get it to arc into a dummy load. The SB-220 is
best run with a Tune Up Chart mounted above the controls. The less time
spent key down and fiddling with the controls the less chance of damage.
Some hams...not just 220 owners ....have the mindset that you have to
tune up every day and/or if you even QSY a bit.
I use a chart with my LK-500ZC and do a real key down maybe 2-3 times a
year...unless I change an antenna. The tubes are original as are the
parasitic suppressors and everything else.
>There are
>no/no indications of parasitics, and I first experienced this
>phenomenon
>before I removed the AG6K suppressors and substituted KM1H's with the
>big
>MU metal straps. Picked up 100-125 watts on 10 meters compared with
>the
>AG6Ks, and it is still fully stable.
>
>Before I get condemned as a Rich-basher, please note that I think his
>input-circuit mods make a lot of sense, as do his QSK and
>anti-hot-switching ideas, among others.
I recommend the AG6K TL-922 relay circuit to anyone who will listen and
have done several here for customers.
Input coil/capacitor changes are also good for the SB-220 but I have no
use for grid circuit and filament circuit mods to the SB-220 series. IMO
they are a shotgun approach that just reduces stage gain to mask the real
problem. As I have mentioned several times the past few years, the
addition of a 10-15pf 1KV silver mica or even a RF doorknob directly
across the 20-40M switch contacts will markedly reduce arcing tendencies.
I have even built several SB-220's with a "hot" xfmr mod that runs the PS
caps right at the edge and 1800W out with no switch or cap arcing with
the above change. I do use the wider spaced Heath Tune cap in that case.
I just don't think that
>everything
>scuzzy that happens on the anode side is due to parasitics.
Very few do...it is just a minority that blindly follow their leader
without understanding Amp Basics 101.
73 Carl KM1H
>
>73, Pete Smith N4ZR
>n4zr@contesting.com
>
>"That's WEST Virginia. Thanks and 73"
>
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>
>
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