[cknob]

Hi everyone,

About 10 years ago, I bought my brother a completely restored Philco 37-650 Tombstone radio as a housewarming gift for his new, retro style home.  The radio had been restored by Lew Magrish and was for sale on the Radio Attic website for around $750.  The restoration included new electrolytic capacitors, re-stuffed Bakelite blocks, resistor replacement, addition of a 1/4" input jack, a successful fix of the shadow meter and a cabinet refresh.  The radio weighed a ton and worked fantastic on all 4 bands, AM broadcast and 3 bands of shortwave.  About a year ago, my brother told me the radio had stopped working.  It had developed a common problem with all 37-650s in that it played fine for a few minutes and then went silent.  I took it to a local vintage radio restorer who got it working again.  After a month, it developed another curious problem, again, sound cutout that could be solved by any number of interventions.  If you turned the radio on and off rapidly 2-3 times or switch bands in the same manner, it would crackle back to life.  Shorting the tuning capacitor with a screwdriver would do the same.  Each time I did this, the radio would play but playing time before cutout would get shorter and shorter.  Finally, nothing would work and get it going again.  Having gotten, with lots of help from this forum, a Philco 90 Lowboy restored to a reasonable playing condition, I decided to take a crack at the 37-650.  I cleaned all of the tube socket pin holes with electronic cleaner and a stiff, narrow nylon brush (great tool by the way).  I cleaned and replaced suspect wiring throughout the radio and on all the tube cap leads.  I sprayed cleaner in the on/off/tone and separate volume controllers vigorously working them back and forth.  I reassembled the chassis, turned the radio on and it seems to work fairly well now.  I left it on for several hours and switched between AM and shortwave bands without any significant issues.  There are some curious idiosyncrasies though.  As you get near a station, there is a high pitched squeal/whistle requiring exact tuning on a station to null it out.  The radio also gets to a decent level of volume about halfway through the volume control rotation but then gets no louder.  I did an AM alignment getting a very strong, loud signal at 470 kc, much louder and cleaner than the broadcast level.

I'm thinking of going into the chassis to troubleshoot and fix what I can to increase performance and reliability.  The first thing I noticed was Lew had re-stuffed the AC line capacitor block with standard, tubular axial lead caps.  Shouldn't these be AC X-Y safety caps? Does anyone have ideas as to where I should focus to address the whistling issue? 

Thanks in advance everyone.

Chris