11-01-2005, 03:52 PM
I have restored two of the 48-482s. Both are good performers. There was a steep learning curve to get the alignment right. Alignment is a long drawn out provedure with special jumpers. Follow it to the letter and the radio works fine. My big problem on the first one was a broken slug in the FM1000 detector coil. I used a slug from an old TV IF and after a lot of 'fanagleing' got it aligned. The IF and detector coil adjustment slugs are VERY fragile. Slightly loosen the lock nut on those that still have them before turning. That way you can tell when the adjustment has reached its limit or is stuck. Also squirt some WD40 (just a tiny amount) down the screw and let it soak before atempting to turn it.
I had hum in both radios until I added a filter choke. The field coil is in the negative lead and the drop across it provides the bias for the set. After a good read of RDH4, I decided to add the filter choke and the hum went away. Apparently the capacitive coupling from primary to secondary of the power transformer induces a loop current that causes the hum. The choke blocks the loop current.
I also added some filtering for the IF strip but not sure it was necessary.
The second 48-482 is the radio we listen to in the computer room. The speaker is small but sounds fine. My wife says it is the best sounding table radio we have. I am not much judge since my hearing stops at around 5KC.
There are LOTS of caps to replace with one special one under the RF deck. I did not have a ceramic to replace it but that would be best. I used two mylar caps in parallel and it worked.
I added a bit more feedback than original by paralleling a resistor around the feedback resistor.
Philco made a console that same year with the same chassis except it had a phase inverter and a pushpull 6V6 output.
I had hum in both radios until I added a filter choke. The field coil is in the negative lead and the drop across it provides the bias for the set. After a good read of RDH4, I decided to add the filter choke and the hum went away. Apparently the capacitive coupling from primary to secondary of the power transformer induces a loop current that causes the hum. The choke blocks the loop current.
I also added some filtering for the IF strip but not sure it was necessary.
The second 48-482 is the radio we listen to in the computer room. The speaker is small but sounds fine. My wife says it is the best sounding table radio we have. I am not much judge since my hearing stops at around 5KC.
There are LOTS of caps to replace with one special one under the RF deck. I did not have a ceramic to replace it but that would be best. I used two mylar caps in parallel and it worked.
I added a bit more feedback than original by paralleling a resistor around the feedback resistor.
Philco made a console that same year with the same chassis except it had a phase inverter and a pushpull 6V6 output.
Kind regards,
Terry
http://home.comcast.net/~suptjud/
"Life is simpler when you plow around the stump."