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

[Will Matney]

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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