The Fine Things are Always Hand Made
Philharmonic AM/FM
Ever since I first heard of EH Scott radios and joined this forum, I've been looking for a Philharmonic to "fall into my lap". Well, when Ron R. sold me his Marine SLRM I saw his AM/FM Philharmonic sitting in the corner. When he offered it for sale, I knew I would own it, I just didn't know how soon. Now, a couple of months later, it's here in my possession. Thank you Ron!
This will be a major project including some re-chroming. I want to do the radio and Ron proud! I heard Dave's (in Northern Michigan) Philharmonic (and a lot of other radios!) and decided I needed to get right on it. So, the work has begun. I decided to start with the amp/power supply as that is the easiest. Because of all the small parts around the transformers, it's also the most expensive to re-chrome (driver transformer cover, IF shields and tube shields will not be re-chromed as they can easily be destroyed, though I may give Dave's re-chroming shop in Milwaukee a try.)
This Philharmonic did not have tweeters. I would like to add them if i can find a set.
Also, since the FM is useless without a converter to the current FM frequencies, I'll be looking for a converter. i saw the schematic in the archives. Maybe i'll have to build one.
Comment
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Comment by Robert Feenstra on February 10, 2021 at 5:39pm
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Thanks Michael! I would just hate to see all those Chinese yellow caps under there. Perhaps Panasonic brown would be better. These do take a lot more room, as you say. Things would be a lot less crowded. But, I figure if the factory could fit it all in, I can too!
The radio has been playing for several hours today without a hitch. I even tested the FM with my signal generator and it works as well. I need to talk to Bill. I also have a couple of TV "subbers" that can be used to make a converter. I don't know if Pentode on the other forum is still making them. I sent him a PM a long time ago and heard nothing back.
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Comment by Michael Lawton on February 10, 2021 at 9:06am
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Congratulations, Robert ! I have followed your work mostly over at Philco Phorum. The pictures of the underside of that chassis were enough to give me the willies! The fact that you got it all rebuilt with so very few problems is a real testament to your accuracy and tenacity. And you did it using re-stuffed condensers, when A, nobody but future technicians who look under the chassis will see them, and B, if you had not re-stuffed the old ones but just used the modern poly caps as is you would have saved a heck of a lot of time and labor, and also opened up a lot of room to see things and to work under that blivvit of a chassis. I admire your work here. It looks amazing, and better yet, works amazingly too.
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Comment by Kent King on February 10, 2021 at 7:26am
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Member Bill Liers makes a modern FM converter. I have one, it works great on my early FM sets. I don't have the thread handy but a quick search should find it, or send Bill a note for more info.
Kent
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Adjusted the bias and that brought a couple of the bands in. The BC band had a solder connection that had let loose from the trimmer cap. Soldered that back up and now all bands are working. Now on to an alignment.
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Well, it didn't blow up! I get stations on 2 of the short wave bands, nothing on the broadcast band, long wave, or the highest band. They are totally silent so I suspect an oscillator problem. I get a lot of noise on the FM band until it picks something up (there are no FM stations at these frequencies - 42 to 50 MHz. When it does tune something in, the FM eye closes and the set goes silent like the limiters are kicking in, killing AM noise. Or so I theorize. On the bands that do work, changing the selectivity control will shut them down. They only work in a very narrow range on the selectivity. This would suggest that the IF alignment is way off. I knew it would be as I cleaned the connections on the trimmer air caps, swinging them through their range and trying to reset them where they were. The first thing I have to do is align the IF as it might bring in the other bands.
Actually, the first thing I need to do is to bring the B- into line. It is supposed to be at -27 volts but is actually at -39 volts, upsetting the bias on the whole system. RF and IF AGC depend on the B- voltages. B+ voltages are just a tiny bit high, but not too bad and will probably come into line when the biases are correct. AF system seems to be working fine. A lot of power available with a radio signal or my finger on the phono input.
The dial lighting system is LED with a control to vary the brightness. That is working. I tried to make some LED bayonet lamps for the "Beam of Light" pointer system. I let a little smoke out on those! I'm going to have to order some of the LED lamps that Ron is using.
One always hopes that everything works first shot out of the box, but that is not to be. I'm very please, however, with where I'm at. Considering the complexity of this radio, I did expect a few problems!! It will be fun to sort everything out and get the radio properly aligned - a fairly major project. I'm anticipating a great preforming radio when I'm finished.
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WTB: Noise Limiter ON/OFF switch. I'm starting to install the controls on this radio and discovered that the noise limiter switch is broken internally. I can see it has been worked on. The detent system is missing completely.. It will work if carefully positioned, but it would be nice to have the detents. If anyone has a chassis that has this switch and can part with it, I'll buy it!
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Yes, that is how mine is wired, to the same location. Thank you!
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Comment by Scott Seickel on January 30, 2021 at 12:58pm
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Rob,
Looking at my one chassis, it does look like the B+ is not switched as the schematic shows. Maybe this was a revision, or maybe it was never implemented.
In the photo below, the 2nd limiter tube is on the left and the B+ wire (tip of screwdriver) goes to the 100k resistor. I am assuming this is the 100k resistor that is in the 2nd limiter plate circuit.
Don't laugh, this chassis was not restored by me. :-)
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I have a question on the switched B+ (230V) to the FM section. The schematic shows that the entire B+ supply to the FM section is switched by the band selector (as well as the RF 1 and 2 of the AM section). However, on this chassis it appears that B+ supply for the FM is connected directly to the B+ on the voltage divider. It is original wire. A lot of caps and a few other components (and part of the candohm) have been worked on. Is it possible that the supply for the FM section was modified, or are there some factory mods from the schematic that supply the FM directly rather than through the band switch? I'm in the process of wiring that now and would like to know if I should modify the chassis to mimic the schematic.
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Reassembly has begun. I started with the RF section by riveting all of the tube sockets and terminal strips. All resistors are outside of 10% so I'll replace all of them
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