On Thu, 26 Feb 2009 17:45:53 -0500, rich ferguson wrote: >I have been working on tr7a., the problem is when the radio is first turned on >and you key microphone the tr relay will not engage. After the radio has been >turned on for 30 minutes the probelm goes away and the microphone will key >the radio. I have replaced the transistors on exciter board.
If you haven't already, I would suggest that you pull all of the circuit boards and clean the Molex connector pins. Radios of this vintage can develop strange intermittents due to oxidation or dirt on the pins. Then look at the circuitry from the PTT pin on the mic connector, through the transmit inhibit circuits (the service manual describes pretty well how it all works), to the relay coil. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." 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 _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
