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Re: [Amps] (Perhaps) A plate choke too far ...

To: Larry <larry@w7iuv.com>, amps@contesting.com
Subject: Re: [Amps] (Perhaps) A plate choke too far ...
From: Radio WC6W <wc6w_amps@yahoo.com>
Date: Fri, 15 Jan 2010 09:06:53 -0800 (PST)
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Hi Larry,

>Why 1-2 mH? 

  So that the choke still behaves as a choke down on 160 rather than becoming a 
significant portion of the plate circuit.

73 & Good morning,
  Marv WC6W

http://wc6w.50webs.com/

--- On Thu, 1/14/10, Larry <larry@w7iuv.com> wrote:

> From: Larry <larry@w7iuv.com>
> Subject: Re: [Amps] (Perhaps) A plate choke too far ...
> To: "Radio WC6W" <wc6w_amps@yahoo.com>
> Cc: amps@contesting.com
> Date: Thursday, January 14, 2010, 10:12 AM
> Marv & all,
> 
> Just some random thoughts which may or may not be
> appropriate/valid:
> 
> Why 1-2 mH? Just curious because if I had a choke design
> that was 250-300 MICRO H and didn't have any resonances
> below 30 MHz I would be a very happy camper.
> 
> Several years ago there was a discussion on this list
> regarding ferrite used in plate chokes. I don't remember all
> of the conclusions but I do remember some examples in
> commercial TX's. Seems like they used a rod/slug *partially*
> inserted into the solenoid choke.
> 
> Re the referenced web page, seems like there are some
> errors there but the end result looks interesting. I would
> like to measure one of those myself as I don't trust most
> guys to get it right.
> 
> Having tried the grid dip meter approach myself, I found
> that was a good way to wind up with all the magic smoke
> escaping the choke in question. Just today while measuring
> the loaded Q of a pi-net in the latest amp project, I was
> able to see and read out the choke resonance to within a kHz
> or so while actually in the sealed up amp and tuned to 10/12
> meters. I use a VNA for this but can and have used a sig gen
> and spectrum analyzer with equal success.
> 
> My normal solution to the choke problem is the restrict the
> number of bands the amp covers. Mono-band amps are the
> best!
> 
> 73, Larry
> 
> Larry - W7IUV
> DN07dg
> http://w7iuv.com
> 
> Radio WC6W wrote:
> > Hi Angel,
> >   The point was to make a rather high
> value (1-2mHy) choke with no resonances in the HF region.
> > 
> >   The saturation gotcha was a
> by-product.
> > 
> >   A rod wouldn't suffice in this
> application.  A gapped core might.  The gap would
> need to be only a few thousand's wide and I don't have a
> diamond saw like that...   Too bad pot cores
> aren't made in 43. 
> > 73 & Good morning,
> 


      
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