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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 7th May 2020, 8:49 pm   #1
g0hze snowy
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Default Kenwood TS430s

Good Evening Gents
just acquired the above ham radio t/rx.
usual problem, blowing fuses, turns out to be the PA module
It would appear the previous owner has had the trannies replaced (or done it himself) unfortunately its a bit of a mess in there, Q2 emitter not soldered!.
I have some measurements, can 1 of the more knowledgeable gents tell me if the 3 legged fuses are toast or ok.

pos test meter to base neg to emitter = 3.1ohms
-----------ii-------- base to collector = 2.7k ohms

neg lead to base, pos to collector = 1.8kohms
----------ii-------, pos to emitter = 3.1ohms

same on both 2sc2879 in circuit!

pos lead of meter to main 12v input, neg to chassis 775mohms
pos lead to 12v drv ,neg to chassis shows 4mohms

I have also found an additional filter wired from FM board to RF board, anybody know of this or have details please.

Hope that's not too many questions in one go.

cheers and beers

Snowy
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Old 8th May 2020, 4:03 pm   #2
g0hze snowy
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Default Re: Kenwood TS430s

Update so far
Found a new 2sd880, measured across its legs and then applied the same test to the pair removed from the PA board, they check out ok, so that 2 less to purchase, but the 2sc7879 are faulty, not keen on getting them from that well known web site that import them from China!.
Snowy
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Old 9th May 2020, 3:25 pm   #3
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Default Re: Kenwood TS430s

If it helps I have bought two matched pairs of PA board transistors from weazle66 on eBay, one pair for a TS-430S, and they have all been fine. Other sellers are available of course, but I have no experience of them. Others on here might...

Martin
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Old 9th May 2020, 5:55 pm   #4
g0hze snowy
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Default Re: Kenwood TS430s

Hi Martin, thanks for that update, I have just emailed the chap, so waiting on a reply
Snowy
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Old 9th May 2020, 9:45 pm   #5
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Default Re: Kenwood TS430s

Martin, weazle66 has no PA devices at the moment, but thanks for the suggestion. Snowy
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Old 10th May 2020, 10:02 am   #6
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Default Re: Kenwood TS430s

Good Morning Gents
Can anybody recommend a good honest seller of RF PA devices, preferably one that isn't in the far east selling ' knock off copies' of the genuine item. looking for finals for my TS430s, 2sc2290 or 2sc7879
thanks
Snowy
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Old 12th May 2020, 5:09 pm   #7
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Default Re: Kenwood TS430s

just checking over the various PCB,s in the radio, decided to replace the smoothing caps around IC8 and 9 on the IF board as they are suspect, also changed the 2 x 2200mf caps on the DC board, I did notice that R180 next to connector 24 on the IF board was fitted but had 1 leg cut, its not on the schematics, anybody know why this would be cut, the component outline is screen printed on the board so must be factory fitted initially.

Th additional crystal filter fitted in the FM board seems to be in the TXB line out of connector 3, pins 5 and 7? to OIF board jnc 22 on the CV line.

Has anybody seen anything like this on a mods site?.

cheers
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