SB-200 plate current

[Greg Beat]

Jeff -

I recommend these 2 sites for SB-200 troubleshooting and
updating/upgrading for Heathkit SB-200 amplifiers.

Bob Norgard's excellent web site (with photos)
http://home.gci.net/~rnorgard/ampnotes.html

Rich Measures, AG6K
http://www.vcnet.com/~measures/

Also, check you filament voltage on the 572B (this is mention in Bob
Norgard's notes)
Too high and you shorten the life of the tubes (Eimac notes)
The 572-B tubes recommended filament voltage is 6.3 VAC +/- .3 VAC.
This means that the tubes should put out full rated power with 6.0 volts on
the filaments.

Greg
w9gb

BTW, Bob Norgard replaces the R21 and R22 with 2 watt resistors, the 1 watt
originals from Heath have a tendency to overheat. Notes on Bob's web site:

Check R21 & R22
Refer to Heath pictorial 10. Look at the two 33 ohm resistors (orange,
orange, black). I have included two new 33 ohm 2%, 2W resistors to replace
your existing ones if they are bad or out of tolerance. Measure yours. You
can measure them in the circuit. They should measure 33 ohms +/- 4 ohms. If
they read over 40 ohms, put in the new ones. One of them has a small
capacitor tacked to one of the leads, so be careful here. Also, if they look
a little off color in the middle like they have been overheated, be
suspicious of them. They are 1W resistors, the new ones are 2W, but about
the same size.


----- Original Message -----
From: "Jeff Stewart" <stewgoat at INDY.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Friday, June 13, 2003 5:30 PM
Subject: Fw: SB-200 plate current


   I just did a visual and a 33 ohm resister off the grid of one tube R21 or
R22 is cracked in two.  The tube on that side has a discoloration on one
side (the gitter appears to be at the bottom) so it may be toast.  Now to
figure cause and effect I guess before I replace the resistor.

Jeff


Do not use Reply (spam logger & catcher).
Reply only through ARRL forwarding service to W9GB

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.asp?list=HEATH
To post - HEATH at LISTSERV.TEMPE.GOV
Archives - http://interactive.tempe.gov/archives/HEATH.html