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Fisher KX-100 (X-100-B) Output Transformer source

richiem46

richiem46

Retired and enjoying life and music!
Subscriber
Starting this thread to try and find a source for output transformers for the Fisher KX-100 (X-100-B) amps. Transendar seems to be out of business and I am looking to pick everyone's collective brains for a source for replacement transformers. The transendars were great but.........

All help Appreciated!

Rich
 
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Since you are a subscriber, you should post in Bartertown for a WTB (Want to Buy) for the trannies. You'll want to mention how many you need. There is a slight difference between right and left part numbers. I believe it is in regards to the wire length on the trannie. You can make either work but it's nice to have the correct one - assuming you only need one.
 
Tim D said:
Since you are a subscriber, you should post in Bartertown for a WTB (Want to Buy) for the trannies. You'll want to mention how many you need. There is a slight difference between right and left part numbers. I believe it is in regards to the wire length on the trannie. You can make either work but it's nice to have the correct one - assuming you only need one.
Click to expand...

I posted something an hour ago in the parts forum. Hopefully someone has one available.
 
Looking at this Edcor potentially. Lead configuration different (2 holes) and mounting holes slightly different but electrical specs seem ok and it has 4-8-16 ohm taps that will hopefully work with the KX-100 grounding the 4 Ohm tap and using the Gnd. for negative feedback. I can always repaint them black........:rockon:
 
Scary that both Edcor and Transcendar are out of the business. I've got several trannies that need re-wound.
 
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I just read this on an old thread:

"This will be taken as heresy by some but here's what a friend of mine did when pondering this
on the same amp you have.
He used two Fender Hot Rod DeLuxe OTs, part # P-TF50438 from Antique Electronics for $41
ea.
These trannies will make purists cringe because the turns ratio is not quite right and they'll say that the freq response, as guitar products will be limited. But the guy who did this just loves them. The sound, the price, the fit, the ease of installation, availability, etc etc, all great. So if you want to do it on a budget, or as a temporary measure while you look for a replacement, it will work."

I'm thinking that I will try these out as the price is (very) right and it will be an interesting experiment. I will order the Edcor's as a long-term solution unless something comes along in Bartertown or on the big auction site.
 
Along the lines of your post above, I would strongly encourage you to maybe see if something else "Fisher" (from a different model) will bolt up (or can be made to bolt up) acceptably. No doubt it can be made to work quite well electronically. You'll end up with a much better result, and much better performance to boot. Edcor transformers are not bad for what they were designed for (general purpose), but are not in the same league as original Fisher transformers.

Dave
 
Working along the lines of what Dave brought up (using another model's Tx's) look for part donor X-100-B's, KX-100's. If you know how to figure out turns ratio on the good transformer and get the output (primary side) impedance, you might be able to use the early 400 receiver Tx's(without the AX suffix on Tx part #. Unit serial# < 47999) The 500B,500C, 800B,800C transformers may also work if their primary impedance is close to what's in your KX-100. The 7868 & 7591 are in the same family of tubes (with the 6gm5), and all call for approx 6.6KΩ on primary side of the transformer.
 
Donor parts come up on the big auction site from time to time. I know. I got a OPT for an X100B project in the queue a while back that way.

Also, since your existing trannies are bad you have nothing to loose by opening them up. I had a KX-100 with one bad OPT and I peeled back the paper and was lucky enough that the lead was broken on the outside of the winding and I was able to repair it and put it back together. The chance is low that you would be that lucky, but what do you have to lose?
 
Thanks Dave, Larry and Tim for your help with this.
I check the big auction site most every day looking for a replacement or perhaps a "Barn Find" old unit with suitable outputs I can potentially use. I tried taking an output transformer apart on a previous restore and couldn't find the "open" on that unit. I will try to disassemble these two after removing then because you never know, might be something visually obvious which would be great of course. I will take photos before I start to have a visual record of things. It is a shame though, this KX-100 had one owner who did a meticulous job assembling it and is very clean. I will use Larry's scrubbing bubbles technique when I remove the outputs though!

Again, thanks for all the feedback on this, too bad about Transendar but hope the folks there enjoy their retirement!
 
I think a strong case can be made NOT to pursue the original transformers. They are known high failure rate components -- by now anyway. A really proper repair would include the installation of Fisher caliber transformers that have shown they can stand the test of time.

Dave
 
Tim: Great thread! I'll be in the garage this evening performing transformer dissections....:D

Dave, I hear you about the original transformers. I have had several failed transformers now just working on four Fishers and there is no telling the condition of any transformer I obtain going forward. Would go Transcendar as I used them before and they were great but that is no longer an option. Not sure where one would find Fisher caliber transformers as replacements but will do my surgery this evening and see what that yields in the meantime.

If not successful I will do the rest of the restoration on the amp and try the Fender output transformers I mentioned previously as they are drop-in replacements and will get it working until Transendar comes back or another similar provider is found. Besides, I'm curious how they will sound.
 
I can't disagree with Dave, but with rewinders Transcendar and Heyboer AWOL and good-used a bit sparse what is a hobbyist to do?
 
PXL_20211008_235425233.jpg PXL_20211008_234935272.jpg

Well I performed surgery on the first bad transformer. This one was open on the blue lead to the Red ct while the blue/yellow lead to CT was ok. It actually played surprisingly well in the KX-100 it came from. The first picture is a view of the transformer core from the top. It kind of looks cooked to almost well-done to my untrained eye. The second close-up shows that the two CT connections were ok as far as I could trace them, However, the Blue connection was severed right at the entrance to the winding spool. You can see where, in the spirit of having nothing to lose, I tried to probe for the stub but it was a lost cause, probably a good thing given the shape of the transformer core.

I'll try the next one tomorrow as my 70-year old eyes have had enough for one night....:naughty:
 
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