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Tube Testing - 46-200
#1

A few months back I purchased an "electronically restored" (re- recapped) Philco 46-200 off of ebay. When the radio arrived much to my dissapointment, it was not as advertised and did not play well. The seller did indeed replace the capicitors and added a long lead wire for the antenna. He also claimed to have tested it for 48 hours straight and had a good clean reception.

Rather than having me ship it back, he refunded half of the purchase price. This was several months ago and it just let it sit until I had more time to look at it.

The trouble is that the signal is weak and when I do tune something in, it sounds garbled like when they change the voices of people in witness protection.

I tested out the tubes and one tube, a 7C6 (used as a substitute for a 14B6) tested marginal.

Another tube issue and question I have is with a tube that should go in the spot where the specs call for a 35Y4 tube. In that spot is an RCA tube that I cannot identify what the tube is. on the base it has an "LU" marking, and on the side of the tube (not the top) I can barely read the numbers "575". I tested this tube on my Heathkit TC-2 tube checker and it indicated a "short".

Question:

(A) Can I test an unknown tube as if it is the tube that should go in that location ?

(B) If I do test as if it is a 35Y4 (and it is not) can I damage the tube ?

At this point I don't know if I should buy replacment tubes for the 7C6 (14B6) and the 35Y4 or just the 7C6.

Any help troubleshooting the radio and answering the tube tester questions regarding mystery tubes would be appreciated.
#2

The first thing I would do is make sure both leads of the built-in loop antenna are connected as they should be. This set needs its built-in loop; it's part of the radio's antenna circuit.

When you say the seller "added a long lead wire for the antenna," it makes me wonder if he or she removed or disconnected the loop?

The loop should be glued to the inside of the cabinet.

If one wire of the loop is disconnected, it will cause the radio to sound garbled as you described.

--
Ron Ramirez
Ferdinand IN
#3

The loop antenna is gone

They added a "long" wire connected to the lead connection points [Wire bridges both lead connectors and then a long (12 foot ?) insulated wire with an aligator clip.

Can I get a replacement antenna (bar or loop)

Additionally, I am getting a hum from the radio, even with the sound all the way down. When I tune the receiver toward 1600 the hum gets worse (Bad electrolytic capacitor ??? even thougt it was replaced ?? )
#4

Schematic here:

http://www.nostalgiaair.org/PagesByModel...013591.pdf

Sounds like this one was hacked. No telling what else may be wrong, but if you can't get your money back :

The 7C6 is completely wrong for this set and will not perform well if at all. Completely different heater voltage and current. Get the correct tube. Don't have an extra 14B6. but would give it to you if I did.

Chuck is right. Check antenna loop, should be 3.2 ohms per schematic, and external antenna lug should be grounded to chassis. It will hum terribly if there is no loop antenna.

If the pilot light works and there is adequate B+ I'd leave the rectifier alone.

Also look for evidence (or lack thereof) of filter and paper capacitors having been changed.

Let us know.
#5

A neat way to identify a tube that may not have a legible # on it is to shine a LCD flashlight on the sides all around, frequently you can make out the #. Also seen people put it in the freezer for about 10 seconds and see if the # becomes visible with the moisture when you take it out. Maybe that may help id the RCA tube. Always best to check a schematic or tube layout for correct positions.

Paul

Tubetalk1
#6

Unfortunately this is a case of buyer beware. The listing for the radio was not representative of what I actually recieved, but that being said, physically, the radio is in excellent shape.

I have order the proper tubes for the radio and will replace incorrect or weak tubes.

My next problem is the fact that the inside of the case DOES NOT HAVE the loop antenna. I have another 46-200 and a 48-200 with the loop antenna intact but this radio does not have one. What was left has been scraped off.

Is there a reproduction out there that anyone knows about that can be purchased. What are my other options.

As always. Thank you in advance for any information. I am a newbie and this is still a learning process.
#7

There are no reproductions. You will have to pull one from another radio of the same model, or make your own.

--
Ron Ramirez
Ferdinand IN
#8

Actually if you have the same set, you can fabricate a similar loop to replace it. Some of the early Philcos had around 5 turns or so and others had more like 20. Emulate the original
#9

so basically, I could create a this cardboard oval, loop a wire 20 times around (glue it down) and then glue to the inside of the radio. What gage wire would this be ?? any ideas ?
#10

Don't think it's that critical, but I'd be inclined to use up some enameled 22 guage from a trashed transformer secondary that is not burned up, or simple insulated hookup wire. If you follow the pattern and get everything hooked up OK, you should be good. Might need a touch up on alignment though.
#11

This old Phorum thread may help:

http://philcoradio.com/phorum/showthread...op+antenna

--
Ron Ramirez
Ferdinand IN
#12

Ron, Thanks for the link. I will definitely try this. I am hoping that once I replace the improper tubes and "fix" the antenna problem, that the radio should be much closer to being functional again.

In any case, since I can at least tune in a station, I still have some hope that I can get it working again.
#13

Ron,

Would this be good wire to use for the antenna construction

http://www.amazon.com/Magnet-Enameled-Co...e+enameled


If not, can someone post a link to the proper type of wire to use.

Thanks !
#14

I think 26 or 30 gauge would be better:

http://www.amazon.com/Magnet-Enameled-Co...s_indust_3

--
Ron Ramirez
Ferdinand IN
#15

Thanks Ron,

Really silly question, but still new to all of this. What gage/type of wire should I purchase to replace the wiring found in the chassie (sp) for the 1939-42 Philco radios. Links to items would be most appreciated.

Thanks.

-Jim




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