Transformer - Output, 8 W, 4kΩ - 9kΩ impedance

Transformer - Output, 8 W, 4kΩ - 9kΩ impedance

Transformer - Output, 8 W, 4kΩ - 9kΩ impedance image 1
Customer image:<br/>"I repair old radios. I couldn&amp;#039;t believe that I found one on your web site. Thank you, Klaus"
Customer image:<br/>"AES P-291 Replacement on Truetone D-1144 console 15&amp;quot; Speaker"
Customer image:<br/>"Replace transformer for my 1930&amp;#039;s Philco 41-290 radio"
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Transformer - Output, 8 W, 4kΩ - 9kΩ impedance image 1
Customer Images:
Customer image: "I repair old radios. I couldn&amp;#039;t believe that I found one on your web site. Thank you, Klaus"Customer image: "AES P-291 Replacement on Truetone D-1144 console 15&amp;quot; Speaker"Customer image: "Replace transformer for my 1930&amp;#039;s Philco 41-290 radio"
In Stock
Output 8 W
Primary Impedance 4,000 to 9,000 Ω
Mounting Centers 2.375"
Weight 0.7 lbs



Wiring Diagram:

Wiring Diagram
Item ID:
RoHS Compliant
Product Measurements by Type
Item Height1.643 in.
Item Length2.797 in.
Item Width1.445 in.
Mounting Hole Center to Center A2.4 in.
Mounting Hole Diameter0.18 in.
Output8 W
Primary Impedance4k Ω - 9 kΩ
Packaging Information
Packaging Dimensions2.8 in. × 1.8 in. × 1.8 in.
Weight (Packaging)0.6283 lbs.
GIF: Wiring DiagramAll Models
GIF: SpecificationAll Models

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Specifications, Files, and Documents

GIF: Specification Specification71.59 KB
GIF: Wiring Diagram Wiring Diagram12.78 KB

Questions and Answers

Click each question to see its answers.
Asked by Anonymous on December 26th, 2016.
Matt H.
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.
May 10th, 2020
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.
Asked by Anonymous on May 24th, 2018.
February 23rd, 2019
you can use P-T31 for this works great.
Asked by ceharizona on August 30th, 2018.
August 31st, 2018
Staff Member
On this transformer, the red wire is the center tap.
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.
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.
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.
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.
Asked by Anonymous on April 26th, 2021.
April 26th, 2021
Staff Member
Z(P) is the impedance across the full winding, blue to brown.
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.
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.

Product Reviews

5.00 out of 5 based on 24 reviews
Tom Lewis - August 6th, 2023
5 out of 5

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.

Richard Conn - June 22nd, 2022
5 out of 5

This is a great product, and a great company to buy from! I have bougth 2 transformers from them now!

MICHAEL J BOESSEN - April 7th, 2022
5 out of 5

Runs cool and sounds great. The mounting holes even matched!

Dan Reeb - January 5th, 2022
5 out of 5

Great for TRF Radios audio stages

MI1800es - November 12th, 2021
5 out of 5

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!

Dwight Baker - July 30th, 2021
5 out of 5

Worked great for my application!

blbii - April 26th, 2021
5 out of 5

Excellent versatile universal transformer with very good price.

D. MOHR - March 4th, 2021
5 out of 5

A real lifesaver at a reasonable price. I have used this transformer in several different radios and always been very happy with it.

aaronalnight - December 13th, 2020
5 out of 5

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.

Aries Kosmetatos - November 22nd, 2020
5 out of 5

These are great as I work on old radios I keep a couple of these always on hand!