The first thing I would look at is the filter cap on the DC-DC converter
("Power Supply") board in the front right corner of the radio. This capacitor
is IMO an "always replace" for any TR-7. Strange things can happen when it
starts to fail, and on a rig that old it most likely is. Replace with a part
specified for 105C temperature if possible.There was also an engineering change to add a 470uF axial cap to the +10v rail. This was added by Drake service to any radio that did not have it. Look for it on the bottom side of the chassis, between pins 10 (+10V) and pin 3 (ground) of the DC-DC coverter board connector. 73 -Jim NU0C On Mon, 20 Jan 2014 20:04:55 -0800 (PST), Leon Zebrick wrote: > >Picked up an early Sr# TR7. It's fine except for a high pitched noise in the >audio. It's continuous and not affected by volume control. Not on transmit >signal. It's not loud, but noticeable and annoying in headphones. Sounds >like one of the oscillators is getting into the audio circuit. Any decoupling >mods or improvements related to this? Sr no. Is in the 600 range. Wonder if >this is something Drake eventually improved on. Or do I have a problem? >Thanks. -- Theres something out of place lets go and poke it with a stick. The Doctor, "Amys Choice" _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
