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Old 13-09-2017, 20:16   #16
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

My M802 radio stopped transmitting, and I had to replace the transmitter. I never had a problem with the tuner.
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Old 13-09-2017, 22:40   #17
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

If you have No SWR indicator when TXing,
You may have cooked your output transistors in the tranciever ,, with no TX power the tuner wont tune .
VSWR at its best will be 1.1:1
Just wondering if here is TX output ,,AS i think the 140 tuner takes 5 wats to trigger .
Hope you sort it soon
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Old 14-09-2017, 01:47   #18
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

Quote:
Originally Posted by Daurin View Post
Which one is that? Key or Start?


I did check that when I had the tuner open on the bench the other day, but considering your experience, I think I'll check it again.

Thanks again to all,
Dirk
Hello,

Sorry, I checked the schematic again and the M802 uses that line as ground so my comment about ANTC is not relevant. Other Icoms use the pin for feedback to the radio on the tuner match.

Best of Luck, Eric
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Old 14-09-2017, 05:09   #19
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

Quote:
Originally Posted by Robert Tilbury View Post
You may have cooked your output transistors in the tranciever ,, with no TX power the tuner wont tune .
VSWR at its best will be 1.1:1
Just wondering if here is TX output ,,AS i think the 140 tuner takes 5 wats to trigger .
This is an idea, especially since it is easy to test.

We know there is some output as the tuner is trying to tune. Regardless, with the radio in high power and FSK or CW key the mic. You should see power consumption increase by 20-25A.

If the current goes up you know the radio finals are fine. If it doesn't go up then either the finals have failed OR the SWR is high enough to trigger the self-protective foldback circuits in the radio even though the SWR indicator is not illuminating.

It is worth 30 seconds to collect a little extra information.
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Old 17-09-2017, 08:06   #20
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

I have some more information that may help isolate the problem.

1) I went over the system again and established 1 ohm or less resistance along the entire counterpoise from the tuner lug to the end of the 3" foil, the connection from the tuner lug to the backstay, a roundtrip along the coax to the transceiver, and each of the control wires. I also opened the tuner back up and found <<1 ohm from the lugs of the counterpoise and antenna to the circuit board. Same with my new 4-gang junction on the control wires and the board, as well as the coax to the board.

2) Friends sailed into Rodrigues a couple days ago with an Icom system compatible with my tuner, so I was able to bring my tuner to their boat and try it. It tuned! Now, their system uses an M801e, and the voltages on the control wires were about 13.0V on power and about 8.5V on Key and Start (when not tuning), whereas my system has been showing about 12.6-12.9V on power and about 5V* on Key & Start. *(Interestingly, my meter actually shows about 8V for just a split second, and then drops to five, every time.) These voltages seem out-of-spec to me...(?) Why would that be? The transceiver is getting upwards of 13.6V depending on the sun on my panels. The voltages measured just outside the transceiver agree within a few percent with the values at the tuner end of the control cable.

3) To say the tuner clicks "appropriately" when tuning is not quite right. It makes one click and gives up; about one second. No clattering like when it tuned properly on the other boat today (especially with larger frequency shifts).

4) Once I had established that the tuner tunes on another system, I opened my transceiver and replaced the control wires' plug (crazy fragile) with another robust 4-gang junction, just as I had already done at the tuner end. Next, I completely bypassed my control cable, first one wire at a time with a massive 10AWG wire, then with a cable bundle with wires of a size about double that of the one provided with the original unit.

Unfortunately, I am right where I started still: TUNE makes one click and then the unit displays "THRU".

Quote:
Originally Posted by Auspicious View Post
We know there is some output as the tuner is trying to tune.
Still seems unclear (as per above).

Quote:
Originally Posted by Auspicious View Post
Regardless, with the radio in high power and FSK or CW key the mic. You should see power consumption increase by 20-25A.
My outgoing power ammeter ALSO recently packed it in, so I cannot read power consumption when I transmit (whistling in the mic on USB). However, keying the mic, I can watch my volts drop from ~12.8 to 12.6V (on the control power wire) over the course of a minute or less, so the unit appears to be drawing appreciable power.

Quote:
Originally Posted by Auspicious View Post
If it [the power draw] doesn't go up then either the finals have failed OR the SWR is high enough to trigger the self-protective foldback circuits in the radio even though the SWR indicator is not illuminating.
Still haven't tracked down an SWR meter out here...

Based on the above, I am increasingly suspecting a problem in the actual transceiver. What could cause the low voltages on the control cables I am seeing coming out of the transceiver?
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Old 17-09-2017, 08:10   #21
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

Quote:
Originally Posted by Robert Tilbury View Post
If you have No SWR indicator when TXing,
You may have cooked your output transistors in the tranciever ,, with no TX power the tuner wont tune .
VSWR at its best will be 1.1:1
Just wondering if here is TX output ,,AS i think the 140 tuner takes 5 wats to trigger .
Still haven't tracked down an SWR meter here. What low-tech test could you recommend to test transmission power?
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Old 17-09-2017, 08:54   #22
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

Quote:
Originally Posted by Daurin View Post
My outgoing power ammeter ALSO recently packed it in, so I cannot read power consumption when I transmit (whistling in the mic on USB). However, keying the mic, I can watch my volts drop from ~12.8 to 12.6V (on the control power wire) over the course of a minute or less, so the unit appears to be drawing appreciable power.
Hmm. Somehow I would expect more of a voltage drop than that if the M802 is putting out somewhere close to full power.

If your M802 is pulling 20 amps during that presumably full power "whistle into the mic" (should be between 25 and 30 amps actually), and voltage drop is only 0.2 V, that would imply that from battery to M802 the wiring resistance is only 10 milliohms. Ten feet of 10 gauge copper wire is about 10 milliohms (not even counting connectors), so you could only have about 5 feet of positive with 5 feet of negative 10 gauge between battery and transceiver to drop only 0.2 Volts at 20 amp draw. What is the length and gauge of your power run from battery to transceiver? I'm guessing that your M802 isn't putting out the power it should. Maybe not even enough to complete a tune.

Chip
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Old Yesterday, 04:26   #23
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Re: Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

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Originally Posted by SoonerSailor View Post
Hmm. Somehow I would expect more of a voltage drop than that if the M802 is putting out somewhere close to full power.
I suspect it isn't. The input power to the main unit (at the plug) is 13.3+ V, while the output to the tuner via the control cable is only 12.6ish. Can't say what power is coming out of the antenna coaxial yet.

Quote:
Originally Posted by SoonerSailor View Post
If your M802 is pulling 20 amps during that presumably full power "whistle into the mic" (should be between 25 and 30 amps actually), and voltage drop is only 0.2 V, that would imply that from battery to M802 the wiring resistance is only 10 milliohms.
But that voltage drop of 0.2V or so is just at the battery, not in the run from the battery to the transceiver. The voltage drop seems to represents a significant power draw by the main unit. Again, my ammeter is out, so can't say exactly how much, but being that it's pulling off nominally 460 Ah of almost brand new, fully charged AGMs (wire run of about 5' each way of #6), a drop of 0.2 V or so seems relatively large over such a short period. Right?
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Old Yesterday, 04:58   #24
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Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

Quote:
Originally Posted by Daurin View Post
I suspect it isn't. The input power to the main unit (at the plug) is 13.3+ V, while the output to the tuner via the control cable is only 12.6ish. Can't say what power is coming out of the antenna coaxial yet.


But that voltage drop of 0.2V or so is just at the battery, not in the run from the battery to the transceiver. The voltage drop seems to represents a significant power draw by the main unit. Again, my ammeter is out, so can't say exactly how much, but being that it's pulling off nominally 460 Ah of almost brand new, fully charged AGMs (wire run of about 5' each way of #6), a drop of 0.2 V or so seems relatively large over such a short period. Right?


I see. If you could put one multimeter lead on the battery positive terminal, and one on positive at the transceiver under transmit load, knowing wire gauge you could calculate current draw. You could also put the multimeter leads on each side of your shunt, and if you know your shunt's ratio (50 mV per 500 A is common so is 50mV per 200 A) you could figure your current draw.

Best of all of course would be to borrow an inline RF power/SWR meter to measure output directly.

You could also try to put a 60 watt bulb between antenna and ground. If on transmit you can light the bulb, you are getting some RF output.

If you are really tough, one hand on antenna and one on ground during transmit would tell you something. Just joking of course!

Good Luck!
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