On Sat, 25 Dec 2010 22:14:43 -0500, Michael & Sue Trussell wrote: >What is happening is on 40 meters after I get the SWR set on low power and >attempt to operate my TR7 on normal power the tuner cannot maintain the power >setting, the meter goes all the way to the right when selected on reflected >power and will remain there until I, release the mic button and of course >affects the transmit power
You may not have a tuner problem. Does the match check OK when you re-check it at low power? Some TR-7s were prone to oscillation in the 40 Meter band segment when operated at full power into a load with a reactive component, which would produce the symptoms you describe. This will not show up into a dummy load. The fix is to either decrease the maximum power level with the ALC control on the bottom of the radio, or modify the predriver board to increase the low frequency negative feedback to keep the PA unit from breaking into oscillation. 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
