Alinco DX-70 clicky relay - Elmers Forum at eHam.net

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eHam.net Forum : Elmers : Alinco DX-70 clicky relay

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Alinco DX-70 clicky relay	Reply
by M0DPU on May 1, 2006	Mail this to a friend!
Can anyone help? We use our Alinco DX-70 radio for Maritime Mobile operation so is pretty important to us. We are also about to embark on a major voyage and so would really like to sort it out fairly quickly. Intermittently we get a spurious clicking noise from within the unit that sounds like a relay. This is without touching anything. When this happens we cannot tranmit (the light goes on but zero output). The receive is affected too, it loses 90% of it's efficiency when this happens. All antenna, ground and power seem to be ok, supply voltage aok. Not a mic problem either. Standard Alinco auto tuner in use, with a long-wire backstay antenna. SWR meter between the TX and the tuner. After a lot of transmitting and/or when warm, the unit seems to be ok. Any ideas anyone, please? Thanks, Guy Oury, m0dpu

RE: Alinco DX-70 clicky relay	Reply
by K6AER on May 2, 2006	Mail this to a friend!
This sounds like the T/R transistor may be leaky or some moisture may be on the board biasing the transistor on and pulling in the relay. When you hear the clickey sound does the receive disappear? Is the transmit OK? There are 12 relays in the low pass filter section of the PCB that could also be making the noise. Is one of your bands non operational? Also there is three more relays in the antenna output selection on the filter board. All of these relays could be a problem. Take the covers off the radio and look and feel to see which relay is going off the reservation. Good luck.

RE: Alinco DX-70 clicky relay	Reply
by K1DA on May 2, 2006	Mail this to a friend!
The Alinco is not a bad radio but if you are expecting to use HF SSB for emergency communoications while at sea you ought to consider a made for the purpose marine SSB radio. Icom makes some which also do the ham bands. The maritime net on 14.300 can be a lifesaver. Extended use in a marine environment requires better weather sealing than Alinco provides. I would check the TR relay system in your radio.

RE: Alinco DX-70 clicky relay	Reply
by M0DPU on May 2, 2006	Mail this to a friend!
Thanks for that. Well, Alinco came back to me and they think that it's the pin diodes on one or more of the bandpass filter boards on the main if board. So I guess I'll try replacing those first and see how it goes. And yes, in answer to your question, when this happens I lose all TX and 90% of RX. Do think what they've said sounds about right? Regards, Guy, m0dpu

RE: Alinco DX-70 clicky relay	Reply
by M0DPU on May 2, 2006	Mail this to a friend!
Thanks for the advice. We've been using the set on board now for about 8 years with no problems up to now. There is no evidence of moisture causing the present problem - Alinco say that it's probably been caused by 'static on the antenna'. Anyway, yes we've been on the 14300 net may times, and as for the radio's performance we've often been told that our signal is far stronger than the 'marine' SSB's. For us, the problem with these is cost - they are often three times more expensive than our little DX-70. We are on a budget and having a radio at all was a bit of a luxury when we first got it. I take your point about weather-resistance for sure but am not convinced that most 'Marine SSBs' are much better than ham radios. We were talking yesterday to a sailor who had 2 aboard and both have failed due to damp. I note that the manufacturers don't claim them to be 'splashproof' as far as I know either? We do carry an EPIRB and marine VHF too though. Again, thanks for your input - it's all interesting stuff. Regards, Guy

RE: Alinco DX-70 clicky relay	Reply
by W4DL on May 3, 2006	Mail this to a friend!
I've seen may PIN diodes get "punched through" due to transients entering the RF chain on commercial radios. You can check these of course like you would any other diode. Have not seen may PIN's used in conjunction with relay T-R switching however. If it is a PIN diode, it should be an inexpensive repair, as long as you don't trash the circuit board! Anchors aweigh!

RE: Alinco DX-70 clicky relay	Reply
by W4DL on May 3, 2006	Mail this to a friend!
I've seen many PIN diodes get "punched through" due to transients entering the RF chain on commercial radios. You can check these of course like you would any other diode. Have not seen many PIN's used in conjunction with relay T-R switching however. If it is a PIN diode, it should be an inexpensive repair, as long as you don't trash the circuit board! Anchors aweigh!

RE: Alinco DX-70 clicky relay	Reply
by M0DPU on May 3, 2006	Mail this to a friend!
Thanks - yep, these are on little circuit boards that are only $6 each or less, and Alinco (Hamdistributors) recommend just cjanging them all. Seems a good fix if it works. Cheers, Guy

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