Thanks Jim,
Oh, and one board has the "called for" 2.7k resistor to ground on the 25v
line, and the other one has a 7k resistor that looks original. None of my
schematics show any change called for. Changing out the caps might be a
good idea.
David
Wd9cmd
----- Original Message -----
From: "Jim Shorney" <jshor...@inebraska.com>
To: <drakelist@zerobeat.net>
Sent: Monday, January 12, 2009 9:21 PM
Subject: Re: [Drakelist] TR-7 Board History and head scratching
Hi David,
On Mon, 12 Jan 2009 20:43:46 -0500, David & Chris Drake wrote:
Looking for some historical information on Drake TR-7 boards.
Welcome to the world of undocumented changes. User information like
what you have provided helps add data points for the collective.
All this started because during an alignment, I could'nt get the required
voltage on the VCO board, (shy by around 1-1.5v) and found I only had 22
volts going in instead of 24-25v.
I can't answer your specific questions about the board changes, but I
would recommend replacing the electrolytic caps on the PS boards -
expecially C2108. They are getting old, and strange things can happen
as they go bad.
73
-Jim
--
Ham Radio NU0C
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A,
GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!
HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
http://radiojim.exofire.net
http://incolor.inetnebr.com/jshorney
http://www.nebraskaghosts.org
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