On Mon, 16 Feb 2009 09:24:32 -0800 (PST), James Cobb wrote: >My main power supply is an Astron RS-35M, but my TR-7 (S/N 46xx) generates >some transmitted audio feedback in the receive audio when used with the >RS-35M.
It may be your cable. The TR7 does have a hefty current drain on transmit, but a 35 amp supply should run it with no problem (assuming good filter caps). This is addressed in GW4ALG's Drake notes, here: http://www.alg.myzen.co.uk/radio/tr7/mods.htm#4 This little jewel is so ofthen overlooked by power cable homebrewers.... My approach was to use two independant feeders (both positive and negative wires) from my 35-Amp Astron clone to the TR7 power connector. The high current rail should be #10 or (preferably) #8, the low current rail can be #16 or maybe even #18. Check your local auto supply store or stereo shop for suitable wire. I actually used GE Mobile radio primary wire for my high current feeders; I don't know what guage it is, but it's THICK. Designed to run 110 watt mobile FM rigs mounted in the trunk. It works very well, and virtually eliminated pilot lamp flicker on voice peaks. I also applied this methodology to my Heath SB104A, with similarly satisfactory results. My recently acquired PS-7 has been given this treatment as well. I'll never use a common feed for the high and low current rails again if I can help it. :) 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 _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
