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TS430S With one blown final (options please)

G

Ghetto

Active Member
Jun 22, 2010
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46
28
Hey Guys,

I picked up a cheap TS430S for a bargain and have fixed the RX and am now working on the low transmit power.

Looking at the RF final board I can see mismatched finals, one is a Toshiba 2sc2290 and the other is a Motorola Trio SRF1174 (926) pink dot. The SRF1174 is showing a base to emitter short while in circuit. NB I haven't taken them out of circuit yet to test but Toshiba tests good (diode test).

Can I ask for your advice please: Can i buy a single mismatched Toshiba 2sc2290 and swap out the SRF1174? How important are matched transistors? Do I need to buy a matched set?

Toshibas are very pricey online, then I also came across HG2290's, I can buy a matched pair for half the Toshiba price as the cheapest option from ebay USA (I'm in Australia). Can i drop in HG2290 without bias changes etc? I see mixed feelings on HG2290 on this forum.

Also the service manual messes with my head in how to check final bias ma, does not seem to make sense compared to me checking bias on older 27mh cb radios which seems fairly straight forward.

Thanks for any advice as always!

Rob
 

Page 43 of the service manual says to:
1. set mode to USB
2. Set mic gain to minimum
3. connect ammeter in series with power supply
4. using the send/rec switch to activate transmitter, adjust both VR1 and VR2 for minimum current reading
5. increase VR1 so the minimum current is increased by 200mA
6. increase VR2 so that this current reading is increased by another 200mA
7. set switch back to send/rec to turn off transmitter.

That is the same procedure as for 27MHz CB radios, except that the send/rec switch is used where the PTT switch is, the current is higher, and instead of putting the current meter where the jumper goes, its in the power supply line.

I'm not qualified to answer the other question, but I'd say if they don't look the same, its definitely a bad idea. In my opinion, they should be matched. Any differences will cause distortion in your signal, current imbalances, thermal instability etc. You might get lucky, but I don't think you will.
 
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Thanks Brandon as always for your advice. So your saying in series with the main power supply running the whole radio?

I kept reading like that in the service manual but it messed with my head.

With some of the online prices I'm unsure.

The HG2290 matched is probably my cheapest option if having to be matched..

The second cheapest option would be bypass finals and make it a QRP rig (I'm seeing output ~10+w pep right now in current state) like what kc4eoe mentioned he did to his TS180 in:

W9CNW

Thread 'Kenwood TS-180S finals replacement'

I recently acquired an old Kenwood TS-180S and the finals need to be replaced. It still has the old yellow dot SRF1714's in it. I have read that the Motorola (not MA/COM) MRF454's and the 2SC2290's are the replacements for the 1714's. I see RF Parts sells matched pairs of 454's for about $93 while the 2290's sell for around $75 per matched pair. Disregarding the price, which would be the better set to get? Which set will drop-in easier? I imagine either way some modifications will be required, am I right? Any info is appreciated.

73,
W9CNW
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and then run the radio through a inline class AB linear to get back to stock power (100w pep). Not sure how I would do this on a TS430s but I am sure someone could help me if I went down that route.

Dearest option is buying new matched toshibas for close to ~AU$300 off ebay USA. Looks like RFParts does not export these transistors to Australia (my QTH) which is why I haven't mentioned their prices.

Part of me would rather fix the finals then run a inline linear but I guess its an option.

Decisions.....Decisions....
 
I would buy two matched ones and readjust the bias according to the instructions above. $28 each from ICA.

www.icamanufacturing.com

HG 2SC2290 — ICA Manufacturing

Will come matched. When you order more then one Features • Specified 12.5V, 28MHz Characteristics • PO = 60W PEP(Min.) • GP = 13.8 dB (Typ) @28M • Omnigold™ Metalization System Description Designed For HF Band SSB LINEAR POWER AMPLIFIER APPLICATIONS Picture is for reference purposes only A
www.icamanufacturing.com www.icamanufacturing.com

Just make sure nothing else is wrong before you fire it up. Don't want to pop the new one.
 
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Thanks brandon, I've seen that page and its definitely my cheapest option I found online being matched HG's. I think I'll do that, I just hope the stock biasing will suit them.

Agreed, I will definitely check the circuit surrounding them before firing it up. That would suck to destroy the new ones instantly :(
 
ok I found an ebay seller in USA that posts matched HG2290s to Australia for similar price as it turns out ICA manufacturing web page above only ships to USA and Puerto Rico....
 
BTW, Has anyone here used the HG2290s and if so do they bias bias differently to Toshibas? (I get what Brandon is saying re: bias above) I think I'll place my order anyway but I just would of liked a bit of feedback from someone using them.
 
Thanks Nomad, I'll update this thread in a couple of weeks once they arrive and I'll let everyone know how they go.
 
Thanks 9C1Driver, I'd rather the Toshibas but RFParts does not ship to Australia hence my HG2290s based on what seller posts to me, they are at US$32 each with US$30 Shipping and they will be matched.
 
I think I just blew my finals. Can someone send me maybe a picture of where the finals are before I open it up. I'm assuming they should be right in plain view. thank you
 
Sorry for the delay in reply. For some reason I didn't see your post earlier. I'll have to check if I get notifications. If you do a search on youtube for "Ham Radio - Kenwood TS-430S Maintenance and Adjustment" by Frank Evoked he has a great video on maintenance including removing the RF board in detail. Even though its 480 res its worth watching. From my reading of articles on the net re: maintaing ts430s finals its worth checking the solder joints around the board close to the finals as well (he reflows the area in the vid above). Theres a lot of tips on the net re: ts430s and finals, eg if you still have factory kurled nut for the antenna socket it can come loose (causing bad earth) and active SWR protection circuit etc. So check you antenna socket is tight or better still use a proper hex nut etc
 

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