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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 28th Aug 2019, 7:25 pm   #1
Triple M
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Default Yaesu FRDX400

My FRDX400 decided to burn out its mains transformer last week taking out the house mains trip at the same time.

Looking at the transformer it looks to be pretty well cooked with melted varnish that has seeped out and onto the chassis.

Is there any one that has a spare (perhaps from a broken for parts) receiver? or possibly someone that can rewind/rebuild the existing unit?

Any help gratefully received as I don't want to scrap what is a fine and (up to the meltdown!)clean radio for the sake of a transformer.
I will be replacing most of the capacitors as suggested elsewhere, but can't see any other obvious reasons for the breakdown.

PS I'm also looking for a 6M converter board for the unit as well assuming it can be fixed..
Thanks in advance
Glenn (G0HPS)
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Old 28th Aug 2019, 9:27 pm   #2
g4aaw pete
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Default Re: Yaesu FRDX400

Hello Glenn

I think if you put this post in the 'wanted' section of the forum, one of our resident transformer rewind experts may be able to help.

Wonder what the HT & LT current requirements are? You may be able to use a fairly standard transformer from another redundant piece of equipment.
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Old 30th Aug 2019, 12:20 pm   #3
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Default Re: Yaesu FRDX400

Hi Glenn,
I had the same problem some years ago. Spent ages looking for a replacement transformer without success. Transformer failure seems to be fairly common with the Yaesu 400 family. Eventually I built an outboard power supply and put it in the cabinet I built to hold a speaker for the receiver and was quite satisfied with the result. Still a decent receiver in my view.
Good luck
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Old 30th Aug 2019, 5:33 pm   #4
dodgy-dxer
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Default Re: Yaesu FRDX400

Repeating my previous advice on Facebook to contact Ed Dinning (Dining?) on this Forum for a rewind

Fred
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Old 31st Aug 2019, 3:46 pm   #5
Andrew B
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Default Re: Yaesu FRDX400

Same here, I mentioned Ed on Facebook as well, you'll find him on "services offered"
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Old 31st Aug 2019, 5:15 pm   #6
Andrew B
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Default Re: Yaesu FRDX400

Quote:
Originally Posted by g4aaw pete View Post
Hello Glenn

Wonder what the HT & LT current requirements are? You may be able to use a fairly standard transformer from another redundant piece of equipment.
It's a monstrous iron lump, rated about 500W or so, multiple taps for 800v, 300v, 150v, + others.
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Old 31st Aug 2019, 5:48 pm   #7
g4aaw pete
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Default Re: Yaesu FRDX400

Quote:
Originally Posted by Andrew B View Post
Quote:
Originally Posted by g4aaw pete View Post
Hello Glenn

Wonder what the HT & LT current requirements are? You may be able to use a fairly standard transformer from another redundant piece of equipment.
It's a monstrous iron lump, rated about 500W or so, multiple taps for 800v, 300v, 150v, + others.
Curiosity got the better of me, so I looked at the manual.
Output from the transformer appears to be:

6.3v (about 3A)
13v ( supplying a few transistors)
200v .

The spec. states 50w power consumption from AC mains.
On that basis, the current requirement doesn't seem particularly huge.
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Old 31st Aug 2019, 8:11 pm   #8
Restoration73
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Default Re: Yaesu FRDX400

Yes it's only a receiver, not the FTDX400/500 transmitter which does have a large transformer, so HT 200V @ 100mA should suffice.
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Old 1st Sep 2019, 11:43 am   #9
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Default Re: Yaesu FRDX400

Quote:
Originally Posted by Restoration73 View Post
Yes it's only a receiver, not the FTDX400/500 transmitter which does have a large transformer, so HT 200V @ 100mA should suffice.
Correct

If he had asked for the FTdx401 mains transformer I may have been able to help him

73 Fred
G4BWP
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Old 1st Sep 2019, 1:11 pm   #10
Andrew B
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Default Re: Yaesu FRDX400

ooopps, should have read the question properly re FRDX not FTDX
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Old 1st Sep 2019, 4:25 pm   #11
m0cemdave
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Default Re: Yaesu FRDX400

I have used a couple of these receivers and noticed that the mains transformers ran extremely hot. I wonder if they were originally designed, and "value engineered" for 60 Hz mains supplies?
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Old 1st Sep 2019, 4:37 pm   #12
G6Tanuki
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Default Re: Yaesu FRDX400

Could be - though remember that in Japan part of the country has historically been 50Hz and another part 60Hz so I guess they'd have designed to tolerate the frequency-spread.

Also looking at the schematic the primary is two windings rated for 117V which are wired in series to get 234V-compatibility. Here, the mains is never below 245V and during the day can go up to 252V - which would significantly stress a designed-for-234V setup.
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