[TMC] R5002 Reciver

[telegrapher at att.net]

Last night i pulled what i had thought was my FRR-49(V) out of the rack
because it sounded terrible.  Audio was quite muffled and distorted. 
Thought there should be a fix for this.  

Looking underneath the chassis i saw that i had previously changed out a
couple of electrolytic caps as a precaution.  Hmmmm.  Voltages appeared
to be way high.  ALmost 45 volts high on the plates.  Also some AC on
the chassis.  WEll better dig into the power supply.  

Disconnected the 470 pf and .1ufd caps from each side of the line.  That
took care of the high AC leakage.  B+ still way high though.  But, the
audio seems to sound a little better.  Pull out the manual.  There are
two schematics in there for the FRR style receiver. In looking at the
power supply i figured i could move the line side tap on the transformer
and drop the voltage down that way.  Looking in the manual the
transformers are different.  The one for the R5007 receiver only has
either a 100V or 220V tap.  Nothing in between.  Also noticed looking
under the receiver there seems to be a lack of .01 bypass caps.  Wonder
why?  

So what i did for the interim is drop the line voltage down to 100V with
a variac and then measure the B+.  Aha.  Now its 255V where it should be
250 and the regulated B+ is 150 as it should be.  Filaments are 6.0. 
But, now the receiver sounds great.  Have been running it since last
night and the audio is very good and the AVC seems to be working pretty
good.  Don't think it was ever great.  Now i can hear the BFO when its
turned on whether the AVC is on or not.  Before when i turned it on i
had to really crank back the RF gain.  Not so now.  

Quite surprised to see that the schematic for this particular receiver
shows a line voltage of 100V instead of the normal 110 or 115.  However,
it do run  a lot better on 100VAC.

the transformer in the FRR receiver has multiple taps on the primary
side and will accommodate i think shows to be 120Vac on the line side.

Just an FYI for those with the R5007/FRR-502 or FRR-49 (V) receivers.

Larry
W0OGH