The PHILCO Phorum
IF Transformer open 46-1203 - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Home Radios (https://philcoradio.com/phorum/forumdisplay.php?fid=6)
+--- Thread: IF Transformer open 46-1203 (/showthread.php?tid=3320)


IF Transformer open 46-1203 - BUbba - 06-01-2011

I have a 46-1203 Radio portion primary of the IF can was open (no voltage on plate there) so I opened it up and could not find the wire to reconnect. Unwound it and re wound but I realised that is not right because turns ratio matters more than DC resistance. Anyway there are 2 part numbers on it.

32-4005 and 39-8061. Is there a cross reference to another type?
Are there any subtitutes or can I use another type to put in? It has 5 wires coming out of it.

What are my options. I cannot get anything out of it as is.

THX

Re: IF Transformer open 46-1203 - Radioroslyn - 06-02-2011

The only things that are critical are It needs to be a tube type, not transistor, the frequency, and which stage it's being used in, input, interstage, or output.
Terry
Ps you could cheat and use a 10mh choke from the plate back the B+ and a small cap like 50mmfd @500V from the plate over to the grid of the next stage. It won't give you the gain or selectivity that the transformer will.

Re: IF Transformer open 46-1203 - BUbba - 06-03-2011

What do I do for the 5th wire? Most IF tranformers have 4 wires coming out of them don't they?

On this one Red is B+, Blue goes to plate of 7B7 Green goes to grid of next stage, Black goes to B- and White goes to Volume pot. I thought most IF transformers had 4 wires?

Re: IF Transformer open 46-1203 - Radioroslyn - 06-03-2011

They do however look at the diagram what you will see is the rf filter (the 2 caps and resistor) are mounted in the can most set will have them outside of the IF transformer. You can do likewise.
Terry

Re: IF Transformer open 46-1203 - BUbba - 06-03-2011

Cool thanx so If I understand this correctly I can get mostly any IF transformer with primary and 2ndary and for the 5th wire just put the 2 Cap and 47K resistor network either inside or outside the can myself.

As long as it is rated for 455KHZ..

Re: IF Transformer open 46-1203 - Radioroslyn - 06-04-2011

Yup That should do it.
Terry

Re: IF Transformer open 46-1203 - Ron Ramirez - 06-04-2011

Bubba

I just looked at the 46-1203 schematic. As Terry said, you can add C301C and C301D as well as R301 to a replacement transformer (C301C and C301D would be 110 pF).

Another option is to find a 2nd IF transformer from a junk Philco set, which will already have these components. Just about any 1946 or 1948 Philco that does not have an FM band will have the output IF that you need. Just a thought, if you would rather not build your own detector filter network.

Re: IF Transformer open 46-1203 - BUbba - 06-07-2011

Is there somthing different about Philco IF output transformers compared to the average? I have tried about 4 or 5 that I got from the radio museum and none of them work.. I can get close but no stations. just the spot where the stations would be chirps and alot of oscillation when I go to adjust for max output.. I had radio with the open one one I rewound but after trying all of these,, nothing.

Anyone got a spare one of these?

Does it make a different that it was an ACDC radio? I used 100pF for theR/C network not 110 pF but that should not matter should it?

Re: IF Transformer open 46-1203 - Radioroslyn - 06-07-2011

No don't think so. What is critical is lead length. Can't use clip leads see if it works. Must be wired in with short leads else it will oscillate and won't align properly. They are the proper frequency?
Terry

Re: IF Transformer open 46-1203 - BUbba - 06-22-2011

OK I replaced the 2nd IF transformer and got it working. I have radio but...

I do not understand the following. If it is normal or not for this 46-1203 ACDC Radio.
In the schematic it has the loop antenna going from the tuner through the 2 ohm loop then to a 35 ohm coil and to chassis ground. I can only get reception when I short the 35 ohm coil to chassis ground.

The other 2 things I noticed is the chassis measures 120VAC to safety ground and 100VDC to safety ground with the plug either polarity..

Is this NORMAL or is somthing shorting to the chassis??

Anyway I have stations now but only when I short that 35 ohm coil to the chassis with just the 2 ohm loop between the variable cap and ground.. I do not understand why this is?

THX

Bubba

Re: IF Transformer open 46-1203 - BUbba - 06-22-2011

Sorry that's 100VDC to the chassis from external ground and 12.5 Volts AC from an external ground. Not 120Volts..
Is this a Normal Reading?

Bubba

Re: IF Transformer open 46-1203 - Radioroslyn - 06-23-2011

Yes it is normal. Your set uses a voltage doubler in the power supply. Truly it's not an AC-DC set as the doubler requires AC to operate. One end of the 35 ohm coil (ant loop) should be grounded to the chassis. The 1ohm coil is a pickup coil for an external ant and is grounded though a small cap to avoid shock hazard.
Terry

Re: IF Transformer open 46-1203 - BUbba - 06-23-2011

That is correct for the 50X6 Set. But on this one 50Y6 with no choke (the resistor model) set as it took me a few weeks to find out. They swapped the values on the antenna. This really screwed me because at the same time as I rewired it to match the schematic I had I was swapping out an open 2nd IF transformer. You don't get reception with them swapped so I thought it was somthing with the IF transformer that was the problem. Then one day I cannot remember how I shorted the 35 ohm that I had on my loop to ground and I got radio.... Then I researched a bit and found out that my model flips the 36 ohms and the 1.2 ohm taps. The loop goes to the 1.2 ohm and the external goes to the 36 ohm tap and the cap. I put it back to original and voila,,, it picks up stations like an S.O.B... I thought it looked original before I messed with it. "But the schematic said......"

This guy had the same problem. I guess you cannot assume you have the right schematic with Philco even though you have the same model. There can be variations..

http://www.antiqueradios.com/forums/viewtopic.php?t=127274&view=next

Thanx for the part about the ACDC radio though.