[AMPS] Re: RF choke resonates around 23.4 Mhz errr 22.4

[km1h@juno.com]

On Wed, 09 Sep 1998 10:20:28 -0400 "Hugo W. Catta" <hugo@banet.net>
writes:


><...snip...>
>
>> Anyway it is:
>>
>> 3 5/8" winding of  #28 single Soldereze close wound on a 3/4" 
>diameter
>> ceramic form. I use the H.H.Smith #2621 which is a 4" long form..
>> Series resonances as measured with a Measurements Model 59 GDO and 
>51J4
>> receiver for readout accuracy are 15.9, 24.2 and 30.5 MHz . I have 
>run
>> well in excess of 1500W out on 10 and 12M in the AL-82 with no 
>tuning or
heating problems but I will admit to no testing in the FM wasteland 
>above
>
>> 29.0MHz.
>>
>
><...snip...>
>
>If your choke resonates only around 700khz from the 12M band and works 
>fine,
>then the behavior of my 3-500z on 15M has little to do with the choke
>resonance , (hhmmm):

Choke reasonances will likely shift a bit once in circuit Hugo. Also
several commercial amps park the resonance right in the CB band yet they
work fine on 10M.
I would not play around with the B&W 800 in your amp just yet.


>20% more Ip, 20% less Ig, over 13db gain than on other bands and 
>brighter
>color on the plate.


That could also be due to your input circuit and/or grid resonance caused
by layout, components, etc.
I have noticed similar performance on several amps that seem to have a
"magic band" where the output is several hundred watts above the others.
Never had time to determine why tho.


 
>Hopefully this coming weekend I´ll have the time to work on the QSK 
>(AG6K´s)
>mod and  will use the opportunity to remove some turns from the choke 
>and try
>to park it around 23.4Mhz which is right in between 10 and 12M.


Be real careful if you do remove turns. Resonances can actually go down
"in circuit" in some instances...I found this out the hard way!

73  Carl  KM1H


>
>
>> 73  Carl  KM1H
>> Amplifier Repairs and 6M Conversions Our Specialty
>>
>
>Thank You all again
>
>73,
>Hugo
>CX9AAK/W2
>
>
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