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Re: [Amps] More parasitic choke questions

To: <amps@contesting.com>, "Greg Weinfurtner" <weinfurt@ohio.edu>
Subject: Re: [Amps] More parasitic choke questions
From: "Carl" <km1h@jeremy.mv.com>
Date: Mon, 26 Jul 2010 17:11:48 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Thats fine if you dont mind losing up to 100W on 10M from a voodoo 
suppressor.

If the original didnt work it means the resistors were fried and out of 
tolerance.

Take a look at any real amp from the manufacturers, no nichrome silliness is 
used or necessary.

Theory: The parasitic frequency of a 3-500 is so far above 10M that no magic 
cures are required. Stick to whats been long proven over many decades.

Carl
KM1H



----- Original Message ----- 
From: "Greg Weinfurtner" <weinfurt@ohio.edu>
To: <amps@contesting.com>
Sent: Monday, July 26, 2010 4:36 PM
Subject: Re: [Amps] More parasitic choke questions


> Hi all,
>          I have a Heathkit HL2200 that was built by NC8V (SK). (Uses a
> pair 3-500Z's) I bought it from him while he was still alive and he gave 
> me
> a photocopy of modifications to help the stability.  One concerned the
> parasitic chokes.  It involved removing the current ones and just removing
> the wire off the resistor.  Then with the same amount of turns, it called
> for a piece of nichrome wire, (available out of a hair dryer, toaster, 
> oven
> element, etc.) instead of the copper wire.  So I used a silver brazing rod
> ($5.00 now...ouch...) to 'tin' each end so that it would be solderable.
> Then it called for me to wind the same number of turns over the resistor.
>
> Theory:  The nichrome wire exhibits resistance and instead of a direct
> short like the copper wire did.  This resistance broadens the 'Q' of the
> choke and helps quell parasitics.  It certainly helped in my amplifier, as
> I could tell an immediate difference, especially using a tuner with the 
> ol'
> gal.
>
> A little off topic about the resistors but something to consider when
> making parasitic chokes.
>
>
> Greg Weinfurtner AEE BSS
> NS8O
> 40192 State Route 689
> Meigs County
> Albany, Ohio 45710
> United States of America
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