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Re: [Amps] TL922A Choke Alternative

To: amps@contesting.com
Subject: Re: [Amps] TL922A Choke Alternative
From: Vic K2VCO <k2vco.vic@gmail.com>
Date: Wed, 09 Nov 2011 14:39:12 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
This is the easiest part to obtain that there is: nothing. I connected all of 
the grid 
pins in my TL922 directly to ground with the shortest possible straps. See 
W8JI's 
discussion here

<http://w8ji.com/tl922_mods_parasitic.htm>

and here

<http://w8ji.com/grounded_grid_amplifiers.htm>

and look for his note on "super cathode drive" here

<http://www.w8ji.com/vhf_stability.htm>

Floating grids in a cathode-driven amp is also one of his "10 biggest mistakes" 
in amp design.

On 11/9/2011 8:56 AM, Mark Robinson wrote:
> I am repairing my TL922A after a grid to filament shorted tube. I found that
> one of the grid to ground rf chokes appears to be short circuited - it
> measures around 0.1 ohms. It looks darker than the coil on the other tube
> base which was actually open circuit. I managed to repair that one and it
> now measures 2.6 ohms. This is part L7 and L8. It has a Kenwood part number
> of  L33-0259-05 and is a 470uH part. This part appears to be discontinued
> and unavailable. Will this Bourns part be a suitable alternative?
>
> http://www.mouser.com/ProductDetail/Bourns/5800-471-RC/?qs=sGAEpiMZZMv126LJFLh8y4rtocMwlKUK4usuRa1xM5o%3d
>
> I am not sure what I should be looking for.
>
>
> 73 Mark N1UK
>
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-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/
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