[Amps] Plate Choke Resonances

[Carl]

The Ameritron is 225uh and the insulation thickness has to be taken into 
account. Use a micrometer to measure the bare wire and then with the 
insulation.

Installation in an amp can move the resonance sufficiently out of 20M and 
the only true static test for the home builder is to wire it in the amp with 
a wire short and use a GDO and calibrated receiver. With a High Q resonance 
it doesnt take much of a shift to present a sufficiently high reactance in a 
ham band.

Carl
KM1H



----- Original Message ----- 
From: "James Colville" <jimw7ry at gmail.com>
To: "Tim Long" <tlong8 at earthlink.net>
Cc: <Amps at contesting.com>
Sent: Thursday, January 28, 2010 9:38 PM
Subject: Re: [Amps] Plate Choke Resonances


> You didn't.
>
> I came up with the same results. A big fat resonance in the middle of 20
> meters. I posted my results a few weeks ago here on the list. I think
> Ameritron uses #29 wire. I have my re-wound choke here and an original
> Ameritron. Mine was about 190uH and the genuine Ameritron is 225 or 250 
> uH.
> Don't remember which now.
>
>
> 73
> Jim W7RY
>
>
> On Thu, Jan 28, 2010 at 6:23 PM, Tim Long <tlong8 at earthlink.net> wrote:
>
>> Thanks Jim.  Didn't measure inductance.  Followed the data that Carl
>> provided as closely as I could, turn-for-turn.  Used AWG #28.  I expected 
>> to
>> get a clone of the Ameritron.  Don't know if I did or not.
>> 73, Tim, W2UI
>>
>> James Colville wrote:
>>
>>> What is the measured inductance?  What sixe wire did you use?
>>>  73
>>> Jim W7RY
>>>
>>>
>>>  On Thu, Jan 28, 2010 at 8:09 AM, Tim Long <tlong8 at earthlink.net 
>>> <mailto:
>>> tlong8 at earthlink.net>> wrote:
>>>
>>>    Hello All,
>>>    I just finished winding a homebrew Ameritron-copy plate choke
>>>    using the
>>>    details provided by Carl.  Thanks to Carl's patience and magnifying
>>>    glass.  Shorting the choke and with a grid dip meter, I observe
>>>    resonances at 14.380MHz, 18.200MHz, and 41.5MHz.  I assume that the
>>>    resonance at 14380 will be problematic, or will the resonance
>>>    shift far
>>>    enough away once the choke is installed?  Experience please.  Thanks 
>>> &
>>>    73, Tim, W2UI
>>>    _______________________________________________
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>>>    Amps at contesting.com <mailto:Amps at contesting.com>
>>>
>>>    http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>>
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