Heath had no problems with a shorted bottom end in any of their SB series of
amps, TX, or Xcvrs.
Running a loop up from the bottom may be one way of finding a sweet spot of
minimum RF. Never tried it but it sounds interesting to experiment....at low
power for starters!
Carl
KM1H
> Vic,
>
> Don't put a shorted strap around the choke. It will look like a shorted
> turn
> and cause excessive current in the choke which may burn a section of the
> choke out.
>
> Somewhere I read that you should not use a continuous band around either
> end
> to terminate the ends of the choke winding. Same thing happens.
>
> 73
> Gary K4FMX
>
>> -----Original Message-----
>> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
>> On Behalf Of Vic K2VCO
>> Sent: Wednesday, March 24, 2010 11:07 AM
>> To: amps@contesting.com
>> Subject: [Amps] Plate chokes (was: Re: placement of RF choke bypass
>> cap.)
>>
>> On 3/24/2010 5:18 AM, DF3KV wrote:
>> > I tried that [RF Parts] choke in one of my amplifiers without testing
>> it first with the
>> > GDO and it just turned into smoke on 10m.
>>
>> I've been working on a choke for a new amplifier project. I've noticed
>> some things which
>> experienced builders probably already know, but I thought would be worth
>> mentioning:
>>
>> a) Even if the gdo has decent calibration to begin with and even if you
>> are careful to use
>> it properly (move it away from the choke to get the smallest perceptible
>> dip) the
>> frequency is pulled a lot near a resonance. I've found it necessary to
>> use it together
>> with a counter to get accurate, repeatable measurements.
>>
>> b) It makes a big difference when the choke is mounted on a chassis (and
>> probably when it
>> is inside a box) compared to sitting on a wooden workbench.
>>
>> I am trying out an idea as follows: I wrapped the choke with Teflon tape
>> and made a copper
>> band about 1/4" in width which I can slide up and down. The plan is to
>> test the choke
>> installed and wired with everything mounted and use this to fine tune it
>> before applying
>> power.
>>
>> For what it's worth my choke is 3-7/8" close wound no. 28 on a 1"
>> diameter ceramic form.
>> I've used the RF Parts choke before successfully, but why pay for
>> something that you can
>> make for nothing?
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
>> _______________________________________________
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>
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