>
>There were a few things I left out of this last post:
>
>I already checked the pointer alignment. at one end it is fully
>meshed and at the other end it is fully open.
>
>The rig I am using for an exciter is a Yaesu FT-920. At first I used
>it without the automatic antenna tuner, but now I use it with the
>tuner enabled. Either way, it has the same effect.
>
>I tried setting the TUNE cap within the desired band and adjusting
>the load for max output, varying the TUNE within the band range.
>This never worked. The most I could get out of the amp is 100 watts
>- what I get with the 920 barefoot.
>
>I checked the band switches and found that some of them were
>tarnished very slightly. I cleaned them with Tarn-X and cleaned them
>again with alcohol (in case the Tarn-X left a residue). Same thing.
>
>I haven't tried playing with the tuning slugs. Is this the key?
>
For those who use a solid state radio, the key is to increase the Q of
the tuned inputs to c. 2.
>
cheers, Mike
>
>
>
>At 01:58 PM 12/8/00 -0500, you wrote:
>>
>>I have an SB-200 (S/N 13643) and I have been having problems
>>tuning it, especially on 10 Meters. I got it off e-Bay for a good
>>price and it seems to be in otherwise great condition.
>>
>>When I tune the amplifier on any band to what I believe is the
>>correct resonance, the pointer on the TUNE knob never points
>>to the correct band, as marked on the cabinet. It always peaks
>>the REL PWR output at a point further to the left of the band
>>scale (with plate current within the specified limit). It is always
>>impossible to tune the amplifier within the proper band scale
>>markings.
>>
>>Secondly, tuning the amplifier on 10 Meters is quite a battle.
>>It usually takes me at least five minutes to tune that thing to
>>anywhere near 400 Watts of output power. Right now, I know
>>it's tuned to the CW portion of the 10 Meter band and I don't
>>want to touch it, for fear of losing that resonant point.
>>
>>The two situations occur when I am tuning into either an antenna
>>or into a dummy load. I used several types and lengths of coax,
>>with the same results.
>>
>>I tried replacing the tubes with NOS, but that didn't help. I also
>>checked the components for physical damage and excessive heat.
>>Nothing seems to be burnt (except a little discoloration on the power
>>supply PCB) and none of the coils seem to be open.
>>
>>Is this normal for an SB-200 of its age? Is there anything I am
>>overlooking?
>>
>>Thanks and 73,
>>
>>Mike, N8MR
>>n8mr@arrl.net
>>
>>Mike
>>kf8bex@oeonline.com
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/FAQ/amps
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>
>Mike
>kf8bex@oeonline.com
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
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Administrative requests: amps-REQUEST@contesting.com
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