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Band switch Model 60
#1

I have the late edition of the Model 60 with the wave trap and the capacitor going from a bakelite block to band switch. I need help on tightening the band switch...too much play and it turn too much when switching bands. I can loose the signal also on occasion. I might be missing a critical washer and I don't think it can be tightened beyond a certain point due to a interior rotation gear or something similar. I don't want to crack the switch so I need some advice.
Also I am giving up on SW band after several attempts to repair it...rewinding of coils, new cap, using different antennas...I do have decent frequency sine waves on this band. I have another Model 60 and the SW does work but it is no really great feature in my opinion. Any thoughts here? Thanks for help.
#2

Well I figured out a low tech solution to the wobbly, too loosey-goosey band switch ....there was a hole in chassis that lined up with a grommet hole in the wafer band....put in a bulletin board thumb tack thru both holes...some gorilla tape and voila....!!!! No more switch turning!!!Icon_clap
Any final thoughts on the SW band not working??? Thanks.
#3

Were you able to align the SW band? can you hear the gen signal while in it?
#4

Morzh, no I tried to get a signal thru but a bit unsure of the proper procedure. I attached SG to antenna and tried to send thru a signal in the SW band frequency range. No signal made it thru...and to my knowledge there is no trimmer or padder to adjust either. Based on my oscope reading, the frequencies are ok as shown in the SW sine wave output. So...still confusing to me!!!! Thanks for help.
#5

Let me restate this as I took another look at signal reception on the SW band...I don't get the rf whistling signal on this band but I do get the audio internal modulation signal. But I am not getting any stations...nor do I know how to align this SW band. Not sure what this would indicate????
#6

What is the RF whistling signal?

When you feed modulated signal within your SW range to Antenna input (use a small cap when doing that in series, like 1000pF), say 12MHz (immaterial, just as an exampe) and you tune your radio somewhere near that frequency, will you hear your modulating tone?
Across the dial or at least in part of the dial?
#7

Morzh: the whistling is the heterodyning of the frequency signal...right? I do get the modulated audio signal thru near or at the frequency called for on the radio dial. I also got the heterodyning now that I took a second look at that lower on the band............but it gets real noisy around the 3 to 4 mc range. The AM band plays real nice!
#8

Well, one step forward, one step back or more like all H**l broke loose.
I actually had reception for once on the SW band. Then the wheels came off.
The screen capacitor went belly up and I had no voltage on the 6A7 screen. I had to get into the Capacitor block ...I thought I had done that when I worked on this radio before. So I replaced all these caps and replaced the old resistors. Also made I few other changes. Now I get no reception...and can't get a signal thru at all. For awhile I was getting a signal for a second or two and then it would disappear. Now I am a bit lost. I had rewound the antenna and oscillator coils on the bottom. And bear in mind I had great AM reception and was trying to get some SW reception. I get a quiet repetitive sound every second like a soft muffled clicking or ticking. Help???
#9

Well, I'd do the dry chopstick probe and poke on switch contacts, resistors, could get lucky. Really old carbon resistors can really be had to find, so I would probably replace all of them that are used for the affected band. Of course it could be something else like a tube which refuses to work on higher frequencies, but you will find it sooner or later. More opinions will also follow.
#10

Still confused on this ... hair already pulled out....sig gen audio comes thru at 42 tube but nowhere else...middle tab of volume control no buzz sound. I thought I had it fixed when I found a 560 K resistor I put in mistakenly for 56 K resistor. No cigar!!!! This radio worked when I fixed it 2 years ago and worked just now till I was messing around trying to get SW band to work. Still prob. have osc. problems but audio signal should get through in spite of an osc. problem...is that right?
#11

Corect, if Audio is gone, first fix problem there. Work backwrds from speaker to antenna. Well that's how I was taught. I think I'd replace the rest of the old resistors along with all of the capacitors as well, and clean tube sockets and pins well, check again any replacements, and you shoud be on the air soon.
#12

Just curious....is it possible to bypass the band switch completely for BC only and what would the wiring look like...???? And counting the antenna coil wiring taps 1-5 cw...what would happen to wires on taps 2 and 3?? Thanks.
#13

There should be no reason to bypass the band switch. When in the BC position, all the contacts are open. When in the SW position, the switch shorts out portions of the various coils. A failure of the band switch could cause a problem with the SW but not likely with the AM.

Steve

M R Radios   C M Tubes
#14

Thanks, Steve. Was trying to eliminate any potential signal killer. Radio went silent when I was working on getting SW to work and I was working with band switch that was real loosey goosey. I might have to bake the IF coils...my next desperate theory to find what is killing the signal. They ohm right on the money though? My audio works but the RF signal doesn't get thru for some reason.
#15

Would a bad antenna secondary on Philco 60 block all reception and RF signals? Or can you bypass antenna circuit to test this theory? Thoughts?




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