[jgj6331]

It had me wondering... those Philco caps just look quite a bit more substantial than the garden-variety brown wax / paper cap of the same value and rating - and they are BLACK!!!.... There likely was a purpose to them - I can't see Philco going to an extra expense unless they had to. Perhaps Ron will weigh in on their significance... I had intended to replace them with standard mylar in any event.

I did take the grill cloth and hold it up to sunlight in the store to check the weave density... it looked loose enough to be acoustically transparent..... well, at least to my ears - 40+ years of rock drumming eventually catches up with you....

[Ron Ramirez]

The black caps could be replacements. I have seen Philco caps that have a black shell, very similar to the "Black Beauty" caps only with printing instead of stripes. These were manufactured sometime in the 1950s. I have a parts catalog that shows them somewhere.

As Codefox said, you can replace them with new mylar caps without any problems.

[jgj6331]

Almost through recapping - but ran into a scary problem.... There are two .003uF caps (1200v) running from the plates of the 80 to ground. All I had available were 2 NOS ceramic disc caps - .003 uF @ 1KV. I subbed these in and I tried the radio... almost immediately I smelled something and one plate of the 80 got cherry red.... I turned it off pronto. Fortunately the transformer survived (but the 80 filament opened up!!!). The smell was coming from one of the ceramic discs which was slightly blackened. I checked it with my meter and it was a dead short!!! I took these out and the radio played fine. My question - what do I replace these with??? Is there a safety cap that will work??? Do I really need caps there anyway??? The shorted NOS cap has me gun shy using ceramic discs now...

[Radioroslyn]

If I was recapping they would be gone! Seems like a great way to burn up the HV winding on your power transformer. National Radio used some caps like that in they're late '40's communications sets. A lot of them now have replacement power transformers because of it.
Terry

[exray]

I agree. Get rid of them.

I had a European set that used this. When I received the set it only had one and it was fried. It was a later date code than the rest of the set so it had been replaced once already. And the transformer secondary was fried on the side where the cap was.

Not sure what the motive was. If it was rf bypassing it would normally be placed on the primary side. All I could think of is that it might be intended to reduce spikes coming from the transformer in the case of fluctuating or nasty power. A cap seems like an unnecessary risk at that point in the circuit.

[Ron Ramirez]

I concur with Terry and Bill.

I just spent a few minutes looking at various Tropic schematics. I own four different Tropic models (41-758, 41-788, 42-730, 42-788) and all four use .003 uF caps from each rectifier plate to ground.

I haven't recapped any of mine yet - right now they are just "shelf queens" - but when I do, they won't have any caps across their high voltage secondaries when I am finished.

[jgj6331]

I've been polling opinions - could go back with Y rated safety caps - either in the current configuration or from line in to ground. The current configuration offers that the caps would only be "working" when the set was on (though at a higher stress level) - while the line setup would be active as long as the set was plugged in.....

[codefox1]

I too would be dubious about the need for these caps. And the lead dressing would have to be addressed too, since the surge upon start up is really serious and arcing may occur. I picked up some 2.2 kv radial caps a while ago, and have used them across output transrormers or plate to plate on amps that needed them to eliminate oscillations at post audible frequencies due to sloppy lead arrangement, but have never seen the same used in power supplies, except that sometimes small .001 capacitors are put in parallel with silicon diodes to keep noise down. Never did this myself, can't see a need. Just one more point of failure.

Could be that the "tropics" were used all around the world, where spikes are (probably) still common on the A.C. mains. Kind of like the caps on the secondary of old auto radio transformers with vibrators, and they had to be 1600 WV or else! I do make it a practice to clean up old NOS ceramic caps that may have been sitting around in a bin for years before installing them. I use a cotton swab or gauze moist with paint thinner to wipe them off, and for sure make wait they are bone dry before installing them.

But like others have said, you probably don't need them at all. Two tricks you could use is to put a silicon diode in series with the 80 for each plate, and add an appropriate fuse on the primary and/or center tap to ground of the B+ winding. Then at keastm you will not be back here looking for a power transformer.

[jgj6331]

By the way..... Here's the "grill cloth" I ended up with compared to what was there.....

[Image: http://i203.photobucket.com/albums/aa304...C01057.jpg][Image: http://i203.photobucket.com/albums/aa304...TROPIC.jpg]

I've got extra if anyone needs it.......

[Ron Ramirez]

Not a bad match, especially for something you found at a fabric store.

[jgj6331]

Other than not yet getting safety caps to replace the "problem" ceramic discs that nearly toasted this radio - I finished the recap a couple of weeks ago. Performance is okay - but not nearly as exceptional as I'd thought it'd be. I'm planning to check alignment when I get the time - perhaps that will improve performance a bit..... The bandspead is really quite disappointing.... you see all these exotic names on the "stationized" dials - only to be rudely reminded they are all - for the most part - defunct.... ..... Sure wish I'd had this radio 40 years ago......

[jgj6331]

Excuse my delay in posting..... but - for those interested - the "NOS" .003uF cap that nearly ruined my day......

[Image: http://i203.photobucket.com/albums/aa304...C01114.jpg]

[Ron Ramirez]

Ouch...

Did you ever check the alignment? What type of longwire antenna are you using (a very long one strung outdoors, a short piece of wire indoors, or ?)?

[jgj6331]

Ron,

No - I haven't aligned it yet... though I have all the info together. Got waylaid in December when I discovered my dog had thyroid cancer (now doing quite well after surgery ) - and by reuniting with an old, dear friend diagnosed with diffusely metastatic adenocystic carcinoma (not doing so well....). Hopefully I'll get back to radios soon. I had been trying it out with a short wire... but have also tried it on a good long wire and was not duly impressed. It receives stations, the audio is satisfactory, selectivity ain't bad.... but sensitivity just does seem to be where I imagined it would be... and this is a bit more noticeable on the bandspread. Of course, I've noticed SW to be sucky on my SS stuff too... ...

[Ron Ramirez]

JGJ,

Good to hear your dog is OK...sorry to hear about your friend.

A radio like a 41-788 needs a good longwire. I would have thought that this radio would pull in stations from all over easily. One of these days, I'll find time to restore my 41-788 and my 42-788 so I can compare the two.