Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

41-280, -286, -287, -290 1st IF Xfmr
#3

Arran;

Thanks for that response. The schematic does seem to indicate that there is an adjustable ferrite slug present. It shows the adjustable trimmer capacitor on the secondary feeding the grid of the 1st IF amplifier tube. Your set appears to match the indicated circuit on this schematic.

I have a Philco 40-201 I restored and it is somewhat similar, in that it uses a broadly tuned RF amplifier (1232 pentode) followed by a 7J7 mixer-oscillator. The 1st IF transformer in it has two ferrite adjustable slugs plus a tertiary winding feeding the suppressor grid of the 7B7 1st IF amplifier tube. So my 40-201 has some significant differences, but similarities at the same time. It appears to be another design to incorporate higher selectivity in the IF circuitry. Philco began to use the broadly tuned RF amplifier on many models for a number of years.

Joe


Messages In This Thread
RE: 41-280, -286, -287, -290 1st IF Xfmr - by Joeztech - 10-20-2016, 07:11 AM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 71 Code 125
Ok guys. Thanks for the input. As for AI this is why I ask the experts. Dandconant — 07:39 AM
Philco 71 Code 125
Technically, that's C-. B- is chassis ground. The resistor between chassis ground and the HV center tap makes the HV c...MrFixr55 — 11:24 PM
54C Cabinet Refinish
hello Roy, I’d follow Arran’s suggestion and use automotive gasket material, which I keep around for situations like th...radiorich — 10:22 PM
Philco 71 Code 125
This might be one of those cases where it's a ground to an AC voltage and B- to DC.RodB — 08:22 PM
Philco 71 Code 125
Really Rod? I know you would not steer me wrong but AI say this is a short circuit? What if I moved the 6 volt center ta...dconant — 06:40 PM
54C Cabinet Refinish
Roy; Personally I would have left the asbestos alone if it were my set, but you can find a modern substitute that som...Arran — 04:51 PM
Philco 71 Code 125
Looks like that might be the B- buss, so that would be correct.RodB — 01:32 PM
Philco 71 Code 125
I noticed on the code 121 schematic the center tap for the 6 volt winding and hv winding are tied together. Is this corr...dconant — 12:16 PM
Philco 45-6365 Universal IFT Instruction Manual
The Philco Parts Catalog for 1942 shows it as usable for 175 kHz, 260 kHz, and 465 kHz. The instructions will show how t...DaleHCook — 11:19 AM
Stromberg Carlson 1500 Squeal
Hello Rob, I agree with you—I have one here at my house that I need to check out. It’s way over-engineered just to make...radiorich — 11:05 AM

[-]
Who's Online
There are currently no members online.

>