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Re: [Amps] sb220 question after mods

To: N7uvh@aol.com
Subject: Re: [Amps] sb220 question after mods
From: R.Measures <r@somis.org>
Date: Sun, 16 Jan 2005 01:37:08 -0800
List-post: <mailto:amps@contesting.com>

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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