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Author Topic: Kenwood TL-922A Filament Transformer or “dead” unit?  (Read 2690 times)
N3QIG
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Posts: 5




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« on: October 23, 2017, 06:42:20 PM »

Does anyone know where I can get a filament transformer or “dead” 922A?
Thanks! Mike, N3QIG
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W1QJ
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Posts: 2606




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« Reply #1 on: October 23, 2017, 11:39:00 PM »

Mike, here are your options if you haven't already considered them.

1. Buying a brand new Kenwood replacement filament transformer.  probably highly unlikely to find one "just like that"
2. Buying a used good one from someone parting out a 922 amp.  More likely than above, but you'll have to wait until someone parts one
3. Retrofitting a completely different unit 10v@15 amps that you can get to fit in the space allotted.  Possible maybe
4. Buying another amp as parts that is in poor shape or not working for more money than just the transformer is worth.  Highly probable
5. Buying another nice TL-922 maybe without tubes in perfect working order and moving your tubes into it and parting out your unit or selling as is.  This can probably be done today for the right price.

Other than those options I don't know what else there is.  Pick one that suits your time frame and pursue it.
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N3QIG
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« Reply #2 on: October 24, 2017, 03:46:00 AM »

Thanks for the reply.....I have several "leads" out to cover all circumstances mentioned....we'll see!
Mike, N3QIG
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N4MQ
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Posts: 139




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« Reply #3 on: October 24, 2017, 04:26:27 AM »

Rewind the transformer or have it rewound as an alternate path, Enjoy, Woody  I did rewind mine on a Gonset GSB100 as a kid.
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WA7PRC
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Posts: 1837


WWW

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« Reply #4 on: October 24, 2017, 04:32:39 AM »

Rewind the transformer or have it rewound as an alternate path, Enjoy, Woody  I did rewind mine on a Gonset GSB100 as a kid.
^ ^ ^ THIS ^ ^ ^

Consider that:
a) winding/rewinding a transformer is neither conceptually nor physically difficult.
b) you're starting with a transformer that is dead... you can't make it any "deader".

Q: What's to lose by trying?
A: Nothing.

In the 1980s, I rewound a DOA HV xfmr for a 13.8V/30A linear PS. Most recently, I rewound a LV xfmr for a homebrew 1500W toob amplifier. Both were easy, cheap, and FUN. Smiley
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N3QIG
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Posts: 5




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« Reply #5 on: October 24, 2017, 04:42:02 AM »

Interesting thought!!!  Might consider asking my repair guy about that!
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KM1H
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Posts: 2499




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« Reply #6 on: October 24, 2017, 07:50:40 AM »

Contact Gary Brown, WZ1M, best rewinder on the continent

Carl
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K1ZJH
Member

Posts: 3308




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« Reply #7 on: October 24, 2017, 08:57:32 AM »

Depending on the amp's condition, you might also consider modifying it to use a five volt transformer.

One issue might be that the Kenwood filament choke might not be able to handle the current, but it
too can be replaced.

Pete
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K8AXW
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Posts: 6312




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« Reply #8 on: October 24, 2017, 09:31:15 AM »

The 922 is to nice of an amp to "part out" or other drastic thoughts.  Either rewind the transformer yourself (Low voltage, high current transformers are fairly easily rewindable - HV transformers is another animal!) I have wound and rewound several LV transformers and everyone worked and are still working after 30+ years!

If you are not comfortable with this solution, follow 1H's suggestion and get a pro to rewind it.  It shouldn't cost THAT much, especially when it will bring your nice 922 back to life!
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AE5GT
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Posts: 44




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« Reply #9 on: October 24, 2017, 11:08:43 AM »

Surplus sales of nebraska has a  10V@15A   no 110815 for 2 3-500z
« Last Edit: October 24, 2017, 11:11:33 AM by AE5GT » Logged
W1QJ
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Posts: 2606




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« Reply #10 on: October 24, 2017, 02:30:25 PM »

Just send the filament transformer to Gary Brown and have him rewind it.  I’m sure he can do ir for you.
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K6JH
Member

Posts: 402




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« Reply #11 on: October 24, 2017, 03:24:27 PM »

WZ1M rewinding service, TL922 filament transformer: $165.

http://members.tripod.com/tubes_tubes_tubes/transformerrewindingservice/id32.html

http://www.eham.net/reviews/detail/8019
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73
Jim K6JH
K6AER
Member

Posts: 4671




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« Reply #12 on: October 24, 2017, 03:31:42 PM »

Is there any reason you cannot use a small 5 volt/30 amp switch mode power supply for the filaments?

https://www.amazon.com/SP-150-5-Supply-Single-Output-Silver/dp/B005T6LFTA
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N4MQ
Member

Posts: 139




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« Reply #13 on: October 24, 2017, 03:41:06 PM »

If the primary is on the outside you only need to rewind that part as the secondary almost NEVER FAILS.  Now its easy to see if the primary is outside or inside.  The finer primary wire is the weak point as the iron never goes bad.  Let us know how you do with this, Woody
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N1UK
Member

Posts: 2081




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« Reply #14 on: October 24, 2017, 04:25:20 PM »

When you have the amp fixed you might want to consider adding a slow blow 1 amp fuse to the primary of the filament transformer. I also added the same fuse to the secondary 80V winding. This will protect the transformer from damage when you have a bad tube with a shorted grid to cathode.


Mark N1UK
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