Re: [Amps] sb220 question after mods

[R.Measures <r@somis.org>]

On Jan 16, 2005, at 1:24 AM, N7uvh@aol.com wrote:

> Hi guys...
>
> Been working on a sb220.. did the rectifer and choke mods. Replaced 
> with
> Harbah parts.
> I have noticed that i don't have a idle plate and grid currant.  All  
> seems
> to run ok.  10 watts drive on 40 meters shows .2 plate amps and about  
> .3grid
> ma.  I like to run my radio into the amp at about 10 watts for  
> 100-150 out for
> rtty contesting.   Ran the roundup and all worked good  at this power 
> level.
> i noticed that the right tube will glow some and the  left tube does 
> not.  I
> also replaced the relay for mine was humming.

A humming DC relay means the 110vdc PS filter C is kaput.

>  When I was putting it the new
> relay in I see that someone as added some caps  from the input coax 
> sheild to
> the bare wire jumper from pin 1 and 3 on the  relay.  I hooked it back 
> on.  I
> have not seen anywhere in posts about  this cap.  Is it normal to not 
> see any
> idle plate and grid with the  mods.  I did pull the zener diode that 
> was
> hooked to the rectifier board  and was wonder if that was keeping it 
> with no idle.
>     First time working on a amp.

I would measure the f.s. accuracy of the anode/plate-I meter with the 
power plug pulled.

> tu for your information and work in this message board.
>
> Pat
> n7uvh
>
>
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Richard L. Measures, AG6K, 805.386.3734.  www.somis.org

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