ALINCO DR-605T VHF GONE

[AA3MO]

My VHF side just dissappeared off the map.  It still receives.  PA Pwr out is virtually gone....but the UHF is still punching.  Anyone else experience this? Is this possibly a TX diode/resistor problem I've seen in some threads? I have the meters and the tools and perhaps the parts- just need some direction here. Problem is constant from power up.

Tnx
Dave

[K0BG]

I'm not that familiar with the 605, but I'd bet it is the final. Most (certainly not all) dual banders use separate finals. If not, could be a driver. In any case, I'd look at the schematic and look for something not common in the final.

Alan, KØBG
www.k0bg.com

[KE3HO]

I had the same problem with mine, only it was the UHF that went out. I accidentally dropped the radio. It was in a padded carrying bag and it fell about 2 feet to concrete. It landed edge first on the back of the heatsink. Right after that the UHF only put out about 3 watts on low and 7 watts on high. DC current draw was still up at the typical 11 to 12 Amps then transmitting on high on UHF. To make a long story even longer, I opened it up and inspected it, but did not see anything at first. Then I looked at it under a stereo microscope at work and I found a very small solder ball that was shoring a capacitor to ground in the output filter on the UHF board. I removed the solder ball with some small needle nose tweezers and everything worked fine after that. I also found several other small solder balls stuck here and there on the board, and I picked them off while I had it open.

This was a rather odd failure, but who knows, maybe you will get lucky and find something similar. Other than that, it sounds like the UHF amplifier chip has gone south.

73 - Jim

[AA3MO]

Wow: Two fast responses. I see an output device in the Main VHF Unit portion of the schematic.  I'll have to open the radio and check it further.  I'd be surprised to see a Final gone when communications are so short and separated. As far as the solder balls go we're cautious in our shop for these animals.  I call them asteroids depending on whether they originate off the solder machine from a bounce, or after the fact during touchup.  That's all you need is to have one roll in the wrong corner.  
I'll take the case apart and do a visual.

Tnx
Dave

[AA3MO]

Nothing visual noted.  Going to Alinco.  Will post the repair/resolution when it returns.

[KC8ADU]

sav17 pa has a crack in its ceramic pcb.
very common and the pa is repairable in most cases.
i see and reair a ton of these.

[AA3MO]

Wish I saw this reply sooner.  I can see where this could be an expansion problem over time and possibly create the NO VHF scenario.  I'll have to wait and see the result.
  Thanks, Dave

[AA3MO]

UGH! The RF Shop says it's the Final for the VHF.  Too expensive for the part-not worth the fix.  The UHF still punches out so I guess it's a single bander for the time being. Transmissions were extremely brief (less than 10 seconds and far apart) so it's very dissappointing.  Even with a bad SWR the rig shouldn't have popped the output if it never had the chance to heat up.  Must've been bad or not properly mounted in production. Oh well.