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

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Output transformer for 41-280 radio
#1

The 41-280 I am restoring has a bad audio transformer. Both ends of the input side are open relative to the center tap, and to each other.

I had a post on the Wanted forum, looking for a replacement transformer (Philco part number32-8120) without success. Having exhausted my other sources I am now thinking about a generic replacement. If anyone does have a good 32-8120 transformer I would definitely be interested in buying it.

For a generic replacement, below is my analysis of what's needed, and would appreciate critique if I've got it wrong:

The speaker measures a 5 ohm dc resistance, so I'm considering it 6 ohm impedance (1.25 multiplier suggested by a reference on radioremembered.org). The Philco 41-280 uses two type 41 output tubes in a push-pull circuit. The Type 41 tube spec I googled (Tung-Sol Lamp Works Inc, 1950) has a Typical Operating Conditions and Characteristics table for both Class A and push-pull circuits, and lists plate-to-plate load resistance as 12K ohms. So 12000/6 = 2K impendance ratio, and a 45:1 turns ratio. The Philco 41-280 specification lists audio output of 2 watts, so I'm thinking a 5 watt rated transformer should be OK.

This seem about right?
#2

This looks about right. If you decide to go with the Hammond universal push-pull replacement it looks like the 125B rated at 5 watts would be the one you may want. Radio Daze sells these. John




Users browsing this thread:
[-]
Recent Posts
Philco model 38 code 121 not receiving signal.
So one last question before I finish this radio. Regarding the speaker and output transformer. I salvaged the original o...Stormlord5500 — 09:31 AM
462ron
It’s on the bottom of the homepage of our Philcoradio.com homepage! Ron462ron — 07:20 AM
Model 70 Cabinet Trim
Steve might have some trim left. Not sure he is making anything.morzh — 06:12 AM
Model 70 Cabinet Trim
Hello musar, First all welcome to the forum and yes that is true that steve stopped making trim . Sincerely Richar...radiorich — 12:13 AM
Model 70 Cabinet Trim
I have recently come into possession of a Model 70.  The trim around the base needs to be replaced.  If this were years ...musar — 12:07 AM
philcorepairbench.com - shadow-meter
Anyone know of a way to recover these files from the repair bench? Thanks. fenbach — 11:16 PM
Philco model 38 code 121 not receiving signal.
That's true. Of course If I were to get a vtvm I'd probably have to sink money in to it to get it working right. Probabl...Stormlord5500 — 08:44 PM
Philco model 38 code 121 not receiving signal.
A DMM is good enough. One rarely has to measure indictance, but if you do, short of getting a serious LCR meter (I hav...morzh — 07:35 PM
Testing a speaker and output transformer Trutone A2-G
You guy's are right on. I found a broken wire on the speaker plug that I replaced and all is well now. Have better volu...murf — 03:43 PM
Philco model 38 code 121 not receiving signal.
I need to get a vtvm. I think that little component tester is just more accurate. Plus it shows the inductance which is ...Stormlord5500 — 03:07 PM

[-]
Who's Online
There are currently 424 online users. [Complete List]
» 1 Member(s) | 423 Guest(s)
Avatar

>