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

Output transformer ?
#1

I have a Crosley 20-AP link here:
http://www.nostalgiaair.org/PagesByModel...003313.pdf

The Output transformer is open on the primary side. The output tube is a 6K6 I have a transformer from Antique supply P-T291 that I've had it looks like it will work just want to make sure.
I've found that the resistance on the primary should be 700 ohms the new one reads 500 ohms, if I use C&1 on the sec I get .7 ohms which is close to the original.
thanks
Ericl
#2

Tube radios aren't all that fussy about output transformers. Use whatever secondary combination that pleases you. There has to be a really large disparity to cause loss of volume or other problems.
#3

 With most output tubes, 42, 6F6, 6V6, 6L6, 6BQ5, you can use a transformer suitable for one of the other types and it will work fine. For the 6K6 you could use one suitable for use with a 41 or a 6AQ5, as there are basically variations on the same tube, not sure about Loctals. Edcore has a good selection of replacements, some of the universal ones will work too but cost more more for including the extra taps to very the primary to secondary ratio.
Regards
Arran
#4

Eric

Fom the sch it is not clear what your voce coil impedance is.
But the simple way to measure it (not exact but more or less) is disconnect your transformer alogether (it is bad anyway) and simply measure the resistance with an ohmmeter.
Then you may if you choose to multiply it by maybe the factor of say 1.2 for a good measure.

For demonstration let us have voice coil impedance equal 8 Ohms.

Then you go here
http://www.radiomuseum.org/tubes/tube_6k6.html
or to any place that lists the tube's parameters and see what your load is.
In this case your load impedance is 7.6kOhms.


Then you go here

http://www.hammondmfg.com/125SE.htm

And see the matching combination for 125Cse series.
The closest you get is BLK-GRN (10kOhms to 8 Ohms).

And when you know your output power (say 3.4W for 6K6) you go here
http://www.radiodaze.com/category/570.aspx

and buy 125Bse.

You will have to run your measurements but still 125BSE is I think a decent match.

Now those are expensive so you might give it a search to see what else is out there.
#5

The voice coil is 3.1 ohms, I soldered the new one in and used the 4 ohm C&1 tap for 4 ohms and a 6k6 per the data sheet and powered it up works great and have good volume range.
Thanks everyone
Eric




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Cannot Adjust an IF Transformer’s cores
It works! I received the PCBs this morning in the mail, and put everything together. I reused the base from the original...jrblasde — 04:32 PM
PT-6 antenna connections
I seem to have lost my way on this PT-6. I see the antenna aerial transformer schematic - I’m reading pins 1 through ...bridkarl — 12:30 PM
40-150 General questions
Good thing you're a good electrician ... the pictures show a lot of rewiring in your future! Take care and BE HEALTHY!...GarySP — 11:52 AM
40-150 General questions
I think RobB has it right. It is a part number and looks like its stamped on the chassis and that wasn't something you ...klondike98 — 11:41 AM
40-150 General questions
It's most likely a part number. Most of Philco part numbers are in that format. I looked at the parts list for this mode...RodB — 08:10 AM
40-150 General questions
Hi Kevin, No, I don't but I like your Quote about being a good electrician. The way I look at it is "The fact ...MrFixr55 — 08:06 AM
Philco 38-7 Speaker
7K should be fine. While not a perfect match (This transformer is meant for 6V6 tubes), Antique Electronic Supply (AES)...MrFixr55 — 08:03 AM
40-150 General questions
I discovered a stamp on the underside of the breadboard on my Philco 40-150. It is"56-1417' in black ink with numbe...Kevin_D — 07:14 AM
Philco 38-7 Speaker
FYI the Impedance of the HR20 (the one I have) secondary of the audio transformer is 5 ohms. The 38-7XX speaker is suppo...tludka — 04:22 PM
Philco 38-7 Speaker
Yeah, don't use the transformer currently on the H-20 (Dopf, I thought "H20, is that new technology, a speaker usin...MrFixr55 — 03:51 PM

[-]
Who's Online
There are currently 2764 online users. [Complete List]
» 2 Member(s) | 2762 Guest(s)
AvatarAvatar

>