[davemc]

Well, I finally got my Philco model 46E, which I understand are quite rare. This one looks to be complete and un-messed with, and even has all its shields in place. No rust on the chassis! Runs on 230 volts DC.

The problem is testing the tubes. The ballast and one 71A are good. But it uses 3 type 14 tubes and 1 type 17. I have 5 tube testers, but none will test these tubes! It looks like the 14 may be similar to a type 24 or 36 but with a 13-14 volt DC filament. The 17 looks like it may be similar to a 27, but again with a 13-14 volt DC filament. The filament voltage I found listed on the schematic in Riders 1. Not sure what the real voltage should be. Does anyone know?

Has anyone tried testing these tubes using 24/36 and 27 settings but with a higher filament voltage? The only choice I have is 12.6 volts, and AC of course.

Thanks!

[Fred R]

Hi Dave,

You are correct in the 14 being similar to a 24A. The 17 is similar to a type 27 with higher voltage on the heater. I used to have a General Electric type 14 made in the early 1940's for replacement in the model 46. It had the later ST shaped envelope. I gave it Robert Millard who used it in his book he published a few years ago on vintage tubes. He has a good photo of it there.

I am fascinated with DC only sets and at this time have an Atwater Kent model 41. It has metal plaques in the inside and on the back warning it is for DC only. I made up a power supply for it but right now I still need to use an isolation transformer (a must with these sets) with an input tap to get the 115 volts DC out of it and a rectifier-filter setup. I am not sure what the current draw of your set is. The Atwater Kent uses a bunch of 112A and 71A tubes in series so the current on my set is probably about 300ma. The Philco 46 may be a little higher.

Fred R

[davemc]

Based on inputs from this and another forum, I tested the type 14's and the type 17 at 24 and 27 settings but with 12.6 volts on the filament. The 14's (fortunately) test good even at 12.6 volts. The 17 tests weak. I may try to craft an adapter for my tube tester that will allow an external filament supply set to 14 volts. But the 17 will probably work (used as 1st audio amplifier/driver in the radio).

One 14 tube was missing in my set and a type 36 was substituted. That would probably work, since the filament current is correct (300ma) - I would just have to reduce the input voltage by 8 volts or so. But I was able to find a NOS type 14 from George Fathauer, so I purchased it. I'll keep the 36 as a spare if a 14 decides to die in the future. I doubt there are many of these tubes around, since they were only used in the Philco 46 and 46E Export model.

The DC power supply will be a problem. Since my 46 is an EXPORT set, it needs 240 volts DC at about 350ma! And it must be fairly clean, since it is the plate voltage for the set.

I also like to collect DC sets. I have a British Ultra Blue Fox "DC Mains" set that needs 240 VDC. I also have an AK 84D (110 VDC version of the AK84), and many 1.5 volt, 2 volt, 6 volt, and 32 volt DC sets (including the rare Philco model 32).

Dave

[Fred R]

Hi Dave,

I am sure you then would know how to build a suitable supply. I forgot that was rated for 220V but I recall only the ballast tube was different. A type 3 was used in the 220 volt set and a type 2 for 110 volts. Of course finding the correct 110 ballast tube would be as difficult as finding 14 and 17 tubes for it. Fortunately 110 to 220 volt transformers are easy to find. The biggest problem I had building a supply for my AK 41 was getting a filter choke with enough impedence and a big enough current rating. I don't play it hours at a time. I am using a filter choke out of an old TV that has a 250ma rating which is just at the limit so it gets a little warm after a while. My set uses five 112A and two 71-A tubes which draw 250 ma and a little more for plate current. With a simple pi filter, I only got 90 volts out of the supply so I use an isolation transformer with a voltage tap. That way, I can get it up to 115 volts DC. The only other DC set I had years ago was a Radiola 33DC with the matching 100B speaker and the optional legs. Sorry I sold it now.

Fred

[davemc]

Unfortunately, the difference between a model 46 and 46E (Export) is more than the ballast tube. I quickly discovered that the schematic in Riders I, which they claim is for the 46 and 46E, is not correct for the 46E. The filament wiring is totally different in the two radios. Parts values (original in my set) are wildly different from both the 46 and 46E parts tables in Riders.

The Philco Repair Bench states that their Philco service packages do not cover the export sets. So I am having to make my own schematic and parts identification/location chart. I took a digital photo of the chassis bottom and am identifying parts and labeling them.

The problem of course is that some of the wirewound resistors are different from both the model 46 and 46E values in Riders. So I don't know if they are bad, or just incorrect in Riders!

Dave

[Ron Ramirez]

Have you looked at this schematic?

http://www.philcoradio.com/tech/images/46.jpg

This is taken from the original Philco Service Bulletin for Models 46 and 46-E, and is indeed different from what is printed in Rider's.

Bulletin 53 (the original Bulletin for Models 46 and 46-E) specifies a Type 2 ballast for Model 46 and a Type 3 ballast for Model 46-E. The two are otherwise the same according to this Bulletin.

While it is possible that yours could be a factory variant, bear in mind that both domestic and export versions of the 46 were made in Philadelphia. It would be a few years before Philco built its Perivale, Greenford, Middlesex (UK) factory for the British/European market.

I, for one, would be most interested in seeing your homemade schematic when you complete it, to compare it to the Bulletin 53 schematic.

[davemc]

Thanks Ron for the information. While the service bulletin is indeed different from Riders, it does not match my set. For example, R28 lugs 3 and 4 in Riders shows 1500 ohms for the 46E and a small value for the 46. That matches my set. But you can see from the schematic in the bulletin that the 46 and 46E could not be the same if R28 were indeed 1500 ohms since it is shown to be in series with the filaments! In actual fact, that section of R28 is in parallel with the 3 type 14 tube filaments in my set, which works out. In my set, the B+ for the 1st audio type 17 tube is tapped off of the filament string rather than supplied from the high B+ line.

The underside of my chassis is stamped EXPORT in ink, big letters.

The resistor values for the 46E in Riders are incorrect - the values in the bulletin are closer to my set. The 46E could not work using the values in Riders! But the schematic in the bulletin could not be correct either since for example the plate and screen voltages on the tubes other than the outputs would be too high. In my set, R37 is 32K rather than 13K.

But the difference between the 46 and 46E is more than just resistor values and the ballast: the filament string wiring on the model 46E is very different from the 46, and makes sense voltage and current wise (assuming the voltages listed in Riders are correct, which they may NOT be).

There was a guy that was selling a 46 chassis on eBay, and he stated that that set was designed to get power from the railroad DC in Manhatten for example. I sure would like to know more about how that was done!

Thanks again,