[Amps] SB-220

[Dave Hachadorian]

The spitting noise is probably the tune capacitor arcing. That is 
a sign of underloading. Turn the load control more clockwise, and 
the spitting should stop. If your load control is already at max, 
the swr may be a little high. In that case, try changing the 
length of your feedline by adding an extension (try 30 feet) to 
present a different impedance to the amp, or tweak the antenna 
for lower swr.

The spitting may have put some burrs on the tune capacitor, and 
you may have to file it down. You can also take a look at the 
spacing of the plates on that cap, and bend them slightly to 
exactly center the moving plates within the fixed plates.

Don't hook up the ALC.

Dave Hachadorian, K6LL
Yuma, AZ

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From: "Jeff" <jwill at chartermi.net>
Sent: Sunday, June 13, 2010 10:09 AM
To: <amps at contesting.com>
Subject: [Amps] SB-220

>  Hello all,
> I just powered up a Heathkit SB-220 and I am trying to load it 
> up on 3.770 MHz. I believe I am loading it up correctly, here 
> are the results:
> Mode: CW
> Power into amp: 65W
> Plate current: .480
> Grid current: .180
> High Voltage (keyed): 2150
> Power out :760W (read with a bird peak reading meter)
> This seems OK on CW but when I switch to high power SSB the amp 
> makes a "spitting"noise when I transmit.
> I am driving the amp with an Icom 761 and have the ALC hooked 
> up from the 761 to the SB-220 and I was wondering if I needed 
> to connect the ALC lead from the exciter to the amp if I never 
> drive it with more than 100 watts in SSB.
> Thanks in advance, 73 Jeff  KA0JW
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