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Re: [Amps] Need info on Heathkit SB-1000 Plate Choke

To: amps@contesting.com
Subject: Re: [Amps] Need info on Heathkit SB-1000 Plate Choke
From: "Will Matney" <craxd1@ezwv.com>
Reply-to: craxd1@ezwv.com
Date: Sat, 26 Mar 2005 14:19:38 -0500
List-post: <mailto:amps@contesting.com>
Jeff,

This dont sound good that you have the RF safety choke opened. This would 
happen if the blocking cap would short and should cause the amp to blow a fuse 
or kick a breaker or possibly lightning damage? I would check the coupling cap 
with a hipot to make sure. If the windings on the plate choke were the first 
few, self resonance can cause this. The correct amount "parks" the self 
resonant band outside of the operating bands. I dont want to get into the 
parasitics part here. The wire size is around 26-28 gage if I recall. Either 
will do as 1-2 turns wont effect it's operation as a L block but might as to 
park its resonance. The number of turns, I have no idea on what they sized the 
choke at in uH. If this is known, the number of turns can be quickly 
calculated. You need to know the value in uH or mH, the rod diameter, and 
length of the winding. The safety choke that's used the most is around 1.2 to 
1.5 mH.

Will

*********** REPLY SEPARATOR  ***********

On 3/26/05 at 10:52 AM Jeff wrote:

>Hello All,
> I recently smoked acouple of windings off my Heathkit SB-1000 plate
>choke when the 
>SWR off the antenna changed and the plate choke arced across the ground
>wire of 
>one of the tuning capacitors. The form is still in great shape. I just
>need the 
>magnet wire gauge and the amount of turns on this choke. 
>
>I noticed the one I have has quite a lot fewer windings then what
>appears in the Heathkit manual.
>
>I also need the info on the RF Choke that goes to ground. This is the RF
>Choke that is 
>located at the output of the output tank circuit. It shows a open to
>ground.
>
>K7XQ Jeff
>Atwater,CA.
>
>K7XQ Webpage:  http://www.elite.net/~k7xq/k7xq.html
>
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