SB 200 Output

[Diane Swynar]

Ron,

When you get the maximum output on 80-meters, is the plate tuning / loading
capacitor fully meshed...?

If so, I go along with Murray's assessment: your padder (a fixed capacitor
band-switched in parallel with one of the variable units to increase its
range) is probably fried. Replace it with one of at least the same rating
in terms of voltage, if not more...and YES, these things DO have occasion
to "go south", ususally at the most inopportune time, too!

In the past I've had to replace them in my homebrew linears, on both the
plate tuning side of things, as well as the plate loading...it happens. My
current linear is a pair of 813's in parallel, & my plate tuning variable
cap has 100 pfd. maximum---I have to switch in fixed capacitors in parallel
with it, on 40-, 80-, and 160-meters.

~73~ Eddy VE3CUI - VE3XZ





> Check the bandswitch contacts for their presence and also the 500 pF 2
> kV silvered mica cap...I think it's a 'padder' for 80 m.
>
> Murray
> ----- Original Message -----
> From: "Ron Notarius WN3VAW" <wn3vaw at FYI.NET>
> To: <HEATH at LISTSERV.TEMPE.GOV>
> Sent: Saturday, November 16, 2002 11:20 PM
> Subject: SB 200 Output
>
>
>> I have unusually low power output on my SB 200 on 80/75 meters.  100
>> Watts drive gives me ~700 W out on 40-15 (my rig doesn't give me 100
>> out on 10, that's another story) but only 120 W out on 3.5 MHz, 200 -
>> 250 W out on
> 3.8
>> MHz, and 300-350 W out on 3.99 MHz.
>>
>> I had it open to put in new finals a few days ago, and no change, so I
> don't
>> think it's the tubes going soft.  Any suggestions on where to look
>> next?
>>
>> 73, ron wn3vaw
>>
>> 'If tin whistles are made of tin, what do they make fog horns out of?'
>> -- from "Does Your Chewing Gum Lose It's Flavor on the Bedpost
>> Overnight?" Lonnie Donegan, SK, 4 November 2002
>>
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