>How about trying a brass slug to reduce the L? I'm kind of leery about
>rewinding the coil.
brass should work.
>I think that there are only 3 turns.
>
Two turns might work ok with the orig. slug. .
>There is no C-out. Either inter-electrode capacitance is used as C-out or
>it's just a plain old L network.
When you increase Q - tube C will not be enough.
>
cheers, Steve
>
>----- Original Message -----
>From: "measures" <2@vc.net>
>To: "Stephen Goldberg" <w2imf@worldnet.att.net>; "AMPS"
><amps@contesting.com>
>Sent: Friday, June 02, 2000 12:26 PM
>Subject: Re: [AMPS] SB-200 more strange stuff
>
>
>>
>> >
>> >I'm back with another weird question.
>> >
>> >I find that on 10 Meters my SB-200 talks back to me. It repeats what I
>say
>> >as I say it. It sounds just like loose laminations in the modulation
>> >transformer of an old AM transmitter.
>>
>>
>> >
>> >What can be the cause of this and is it an indication of any serious
>> >problem?
>>
>> Loose windings on the hv RFC. Try this: Pull power plug, wait until hv
>> is fully discharged. Remove cover, dip tip of finger in urethane
>> varnish, rub on windings of hv-rfc until you have a smooth coating. .
>> Let dry c. 1 hour. If it still talks back, go for an exorcism.
>>
>> >As an afterthought, the input match on 10 Meters is terrible. I've been
>> >able to get the input SWR down to a bit over 3:1 by replacing the fixed
>cap
>> >with an adjustable ceramic trimmer. I would like a better match.
>Adjusting
>> >the coil slug makes no difference.
>>
>> indicates too much L.
>>
>> >I've searched AMPS archives and no one,
>> >it seems, has come up with a satisfactory solution other than using an
>> >antenna matching unit between the exciter and the amp. There MUST be a
>> >better way. Can anyone help?
>> >
>> To improve the input match for use with solid-state radios, increase the
>> Q of the tuned input. This involves decreasing L and increasing C-in.
>> Xc-in should be c. 20 - 25-ohms. C-out is best determined
>> experimentally with the amp. being driven to half or more suds. The
>> length of the coax affects the tuned inputs, so stick with one length.
>>
>> cheers, Steve
>>
>> - Rich..., 805.386.3734, www.vcnet.com/measures.
>> end
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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