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Author Topic: TS-430S - Smoked (literally) Finals?  (Read 10533 times)
WA0ZZG
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Posts: 157




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« Reply #15 on: March 19, 2012, 10:42:44 AM »

Here is what information I can pass along on you radio:
1. If you have to pay a shop to replace the finals, it's not worth it.  Cheaper to go get another radio on the used market.
2. Finals don't smoke, the parts around them do.  This makes for more than one part to replace.
3. Finals need to be replaced as matched sets, in these old rigs.  Can be had from rfparts.com. But not cheap.
I've done it in a TS-140S.  Best to have someone experienced show you how, the first time.

Dave
WA0ZZG
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KA5IPF
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« Reply #16 on: March 19, 2012, 12:51:43 PM »



That is why they are limited to 25 watts carrier.
[/quote]

That makes absolutely no sense.

Clif
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W8JX
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Posts: 5647




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« Reply #17 on: March 19, 2012, 02:17:10 PM »



That is why they are limited to 25 watts carrier.

That makes absolutely no sense.

Clif
[/quote]

Sure it does because of PEP power in AM mode can be 4x carrier power and higher average dissipation on finals than in SSB.
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KE3WD
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« Reply #18 on: March 19, 2012, 02:19:56 PM »

Like I said earlier in this thread, Amplitude Modulation is not understood very well by many amateur license holders today...

73
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KA5IPF
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« Reply #19 on: March 19, 2012, 07:07:18 PM »

I understand it perfectly well, and how it operates. Old style tube rigs, broadcast transmitters, and solid state ham rigs.

Somebody doesn't.  Read the entire post. I abbreviated too quick.  CUL

Clif
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W8JX
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Posts: 5647




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« Reply #20 on: March 20, 2012, 09:53:03 AM »

Old time broadcast used large audio amps for plate modulated AM which was far more efficient than controlled carrier AM used it today's rigs in that the high input audio levels/energy were converted to RF and became part of output signal. 
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KC2VDM
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Posts: 145




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« Reply #21 on: March 25, 2012, 06:18:23 AM »

Off topic yes, but I think any new Ham who hasn't had the chance to try AM should. The sound is amazing compared to SSB.

Hope you get your TS430 fixed! I'm working on a 440S right now. It reminds me why I liked working on my Drake instead. There is actually space to work!  Grin

-Alex
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W8JX
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« Reply #22 on: March 25, 2012, 06:22:57 AM »

Off topic yes, but I think any new Ham who hasn't had the chance to try AM should. The sound is amazing compared to SSB.

It does create a "amazing" amount of interference to SSB signals near it.
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KC0YMX
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« Reply #23 on: March 25, 2012, 03:59:20 PM »

I have a question since we are talking about the TS 430.  I'm not the best with electrical things.  I bought one of these as my first HF rig.  The radio will seem fine but then signal and audio drop suddenly and its like the radio only is receiving about 1/4 of what it was.  If you key up quickly it'll kick out of it and both audio, signal shoot back up to normal.  It does it all the time, and would like to know what may be causing it.  Its very frustrating because I love the radio and I love to sit back and listen a lot.  But like I said one minute its sounding and receiving excellent then BAM! It just gets quiet and receive goes way down.
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W8JX
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« Reply #24 on: March 25, 2012, 05:24:48 PM »

My first guess would be T/R relay the switches rig/antenna between transmit and receive is going bad. 
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WV2O
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« Reply #25 on: April 16, 2012, 06:49:14 PM »



I just re did my pa board in my 430s, final transistor was shorted causing voltage to run across the board. I replaced  2 new final transistors (2sc2290-j a matched set)) and 1 bias transistor (2sd880) and new resistor I believe it was r-15, r-15 was the resistor that went up in smoke lol!

after an hour or so of carefully removeing the pa board i was able to replace the finals, also touched up the cold solder joints on the back of the board.

Not hard to do!!!! Just take your time!!!!! all the info you need is on the web!!!!!!!! If I can do it, so can you!!!
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KA5IPF
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« Reply #26 on: April 17, 2012, 05:35:56 AM »

I have a question since we are talking about the TS 430.  I'm not the best with electrical things.  I bought one of these as my first HF rig.  The radio will seem fine but then signal and audio drop suddenly and its like the radio only is receiving about 1/4 of what it was.  If you key up quickly it'll kick out of it and both audio, signal shoot back up to normal.  It does it all the time, and would like to know what may be causing it.  Its very frustrating because I love the radio and I love to sit back and listen a lot.  But like I said one minute its sounding and receiving excellent then BAM! It just gets quiet and receive goes way down.

Look up Kenwood Service Bulletin #902 (available at www.mods.dk under TS430, look for "TS-430S Low/intermittent RX"). Change the step to 1 MHz and cycle thru the bands for about 2 minutes and the problem will be gone.

Clif
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WA9UAA
Member

Posts: 313




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« Reply #27 on: April 21, 2012, 04:54:25 AM »

Hi Clif,
I had heard in the past that some TS-430s had a resistor in place to feed some DC across the receive contacts on the T/R relay i.e keeping oxidation from building up. Just wondering.
73,
Rob 
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AA4HA
Member

Posts: 1386




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« Reply #28 on: April 21, 2012, 10:20:30 AM »

Hi Clif,
I had heard in the past that some TS-430s had a resistor in place to feed some DC across the receive contacts on the T/R relay i.e keeping oxidation from building up. Just wondering.
73,
Rob 

That is an incredibly common problem on more radios than you can count on all of your fingers and toes. Some geniuses only looked at the maximum current rating on relays and it has almost always been poorly understood that relays actually require a very slight amount of current to keep the contacts from completely oxidizing over and becoming insulators. One of the first places that problem was ever seen was in telephone relays and is one of the reasons (among many) on why telephone circuits have -48 VDC.

Even extraordinarily expensive radios have that problem. It is one of the reasons that I can pick up Harris RF-350K's for so cheap when the relays on the filter board start throwing up errors on BITE tests people want to get rid of the radio. (other reasons, they make not so good ham radios, no BFO, no RIT, things that we see as "essentials" on modern rigs).

Some manufacturers use PIN diodes instead of relays. It also makes for a quieter radio that is not clacking away as you change bands. The resistor to add a slight amount of current sometimes introduces a slight amount of signal loss to the receiver (another path for low level RF to go places other than to the next RF stage). The downside of PIN's is that they blow out fairly easily... tradeoffs, it is all about tradeoffs.
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
KD5FHW
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Posts: 35


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« Reply #29 on: April 13, 2013, 11:09:41 PM »

I hate to dig up a dead thread, but I figured I'd post the results of the issue for those that may have a similar problem in the future.



I just re did my pa board in my 430s, final transistor was shorted causing voltage to run across the board. I replaced  2 new final transistors (2sc2290-j a matched set)) and 1 bias transistor (2sd880) and new resistor I believe it was r-15, r-15 was the resistor that went up in smoke lol!

after an hour or so of carefully removeing the pa board i was able to replace the finals, also touched up the cold solder joints on the back of the board.

Not hard to do!!!! Just take your time!!!!! all the info you need is on the web!!!!!!!! If I can do it, so can you!!!

It turns out that our 430 did basically the same thing. New finals, bias transistors and bias resistors and she was good to go. I think the shop took mercy on me and gave me a deal on the repair. I liked the radio so much that I bought it from my brother-in-law and then sold it a month or so later when I picked up my TS-590S. I should've kept it as a backup rig, but I wanted an antenna analyzer.
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