Transformer - Output, 8 W, 4kΩ - 9kΩ impedance
| Specifications | |
|---|---|
| Output | 8 W |
| Primary Impedance | 4,000 to 9,000 Ω |
| Mounting Centers | 2.375" |
| Weight | 0.7 lbs |
Specification:
Wiring Diagram:
| Item Height | 1.643 in. | |
| Item Length | 2.797 in. | |
| Item Width | 1.445 in. | |
| Mounting Hole Center to Center A | 2.4 in. | |
| Mounting Hole Diameter | 0.18 in. | |
| Output | 8 W | |
| Primary Impedance | 4k Ω - 9 kΩ |
| Packaging Dimensions | 2.8 in. × 1.8 in. × 1.8 in. | |
| Weight (Packaging) | 0.6283 lbs. |
 Wiring Diagram | All Models |
| Specification | All Models |
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Questions and Answers
Click each question to see its answers.
2 answers
What is the maximum D.C. bias for this transformer?
Asked by Anonymous on December 26th, 2016.
December 29th, 2016
Staff Member
It doesn't appear as though we have that spec available for this transformer in particular. Both Hammond 8 Watt versions 125C and 125CSE have a max DC bias of 60 mA. Someone might consider that rating as a ball park reference for similar transformers, but you may want to consider the Hammond's instead of P-T291 if you need a guarantee on the rating.
I believe that some push pull output transformers are built without an air gap in the core. In the primary of a push pull transformer the DC bias currents will cancel out provided the plate currents of the 2 tubes are equal. Then there will be no DC bias on the transformer. If the plate currents aren't equal, the difference between the plate currents is the DC bias on the transformer. If the transformer has no air gap, I suspect it would have very little tolerance for any DC bias.
1 answers
Hello,
I have a Hallicrafters SX-62 (not the SX-62A) which I believe has a bad audio output transformer. What would be a suitable replacement?
Thanks,
Lou
Asked by Anonymous on May 24th, 2018.
you can use P-T31 for this radio.it works great.
1 answers
Is the brown wire center tap for primary? No drawing shown for the primary side; rather 2 drawings for secondary connections! Thanks!
Asked by ceharizona on August 30th, 2018.
August 31st, 2018
Staff Member
On this transformer, the red wire is the center tap.
1 answers
Hello I have a bad power transformer on my SX-62. Do you have a correct replacement? Thanks.
Asked by Anonymous on September 6th, 2019.
September 10th, 2019
Staff Member
We do not have sufficient cross reference material to verify the transformer required for your unit. If you can provide the specs required for the unit, please contact us direct and we can attempt to get you a replacement.
1 answers
Please let me know if this transformer will work in my Newcomb phonograph, which I am converting into a guitar amplifier. It has Push-Pull 50L6's driving an 8 ohm speaker. The schematic calls for a TR-215, but the primaries of currently available versions have no center tap. I have seen a similar schematic with 25L6's that calls for a 3000 ohm primary, but does not give a speaker impedance. I can send the schematics.
Thank you
Asked by Anonymous on June 22nd, 2020.
June 22nd, 2020
Staff Member
The lowest primary this transformer is rated for is 4000 ohms so it does not look like it will be compatible with your requirements.
1 answers
My radio sends 400 dc volts to the transformer. Can this handle that?
Asked by Anonymous on July 19th, 2020.
July 22nd, 2020
Staff Member
As long as you are not exceeding the power rating of the transformer this will be fine.
1 answers
Will this work with a single ended 6F6 output?
Asked by Anonymous on November 6th, 2020.
November 9th, 2020
Staff Member
This transformer is meant for use with push-pull configurations. The P-T31 is a single ended transformer we carry that might be better for your application. Customers have reported that it works well with a 6F6 but please check your application to verify this.
1 answers
Are the blue and brown wires on the primary used for both an impedance of 4k ohms and 9k ohms with the red wire always being a center tap or is the red wire used with one of the others for an impedance of 4k ohms?
Asked by Anonymous on April 26th, 2021.
April 26th, 2021
Staff Member
Z(P) is the impedance across the full winding, blue to brown.
1 answers
Will this work with push/pull 6L6 tubes?
Asked by Anonymous on August 24th, 2021.
August 24th, 2021
Staff Member
This unit will work with the following tubes in a push pull configuration: 6F6, 6K6, 6V6, 41,and 42.
1 answers
Hello,
I need a audio output transformer to match up with a 6K6 GT power output pentode tube. Will this transformer work? I only have a 3.2 ohm speaker to hook up to it. Will that be a problem?
Asked by bzadel on April 10th, 2022.
April 11th, 2022
Staff Member
This transformer works with 6K6 tubes in a push pull configuration. A 4 ohm speaker would be preferred over 3.2 ohm since 4 ohms matches the recommended configurations in the datasheet.
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Product Reviews
I used this transformer in a Hallicrafters SX-62A. The original audio output transformer opened up and quit working. I had to drill and tap one hole because the new one is slightly shorter than the original. It works great and with the two 6V6 tubes driving it, the sound is great.
This is a great product, and a great company to buy from! I have bougth 2 transformers from them now!
Runs cool and sounds great. The mounting holes even matched!
Great for TRF Radios audio stages
Great transformer! Used it as a replacement for a failed audio output transformer in an old radio using 2 - #45 output tubes. Replaced the trashed dynamic speaker with a PM, it sang like a bird!
Worked great for my application!
Excellent versatile universal transformer with very good price.
A real lifesaver at a reasonable price. I have used this transformer in several different radios and always been very happy with it.
This seems to be the correct output transformer for Emery Sound Superbaby and Microbaby amps. It fits good and sounds great, so I'm calling it a win.
These are great as I work on old radios I keep a couple of these always on hand!