Icom AT-140 tuner with M802 HF radio (SSB) stopped tuning

[maxingout]

My M802 radio stopped transmitting, and I had to replace the transmitter. I never had a problem with the tuner.

[Robert Tilbury]

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
VK2LOZ

[ejs]

Originally Posted by Daurin

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

[Auspicious]

Originally Posted by Robert Tilbury

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.

[Daurin]

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".

Originally Posted by Auspicious

We know there is some output as the tuner is trying to tune.

Still seems unclear (as per above).

Originally Posted by Auspicious

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.

Originally Posted by Auspicious

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?

[Daurin]

Originally Posted by Robert Tilbury

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?

[SoonerSailor]

Originally Posted by Daurin

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

[Daurin]

Originally Posted by SoonerSailor

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.

Originally Posted by SoonerSailor

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?

[SoonerSailor]

Originally Posted by Daurin

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!

[Daurin]

I am afraid that very little progress has been made bringing my M802 back online.

However, I sailed to Mauritius and hooked up with a technician who brought out an SWR meter. We found that no power was coming out of the transceiver on the coaxial antenna cable. He brought the unit to his shop for bench testing and confirmed that all of the relays were working properly, and no capacitors had burst, but one tiny transistor may be malfunctioning. He admitted defeat at this point, stating that the transistor was simply too small for human hands to micro-solder. I suggested purchasing a replacement circuit board, but he urged against it, fearing that other undetected malfunctions could lead to a repeat burn-out. I then suggested purchasing a new transceiver (without all of the peripherals like the control head, etc.), but that is proving very difficult to source. For that matter, even getting a whole new M802 shipped here is going to be a lengthy, expensive nightmare. We have been in touch with four Icom distributors in Mauritius and Reunion over the past week or so, but still have no concrete answers.

This raises two questions for this forum:
1) One distributor tells me he can source an IC-M802 from Icom France, but it is without DSC. Was an M802 ever built without DSC? I noted that on the Icom Japan website (IC-M802 General version | Products | Icom Inc), the M802 listed mentions nothing about DSC in the brochure, and the photo of the face says simply "CALL" where my radio says "DSC". Surely, CALL is a reference to DSC...but what is the story? (Incidentally, I have read up on some of the flap about DSC changes made in the past few years with respect to the M802 (e.g. http://www.made-simplefor-cruisers.c...%2012-2015.pdf, but this in no way mentions M802s built with no DSC at all)

2) What are your thoughts as to how the radio burned out to begin with, and what the likelihood of it happening again is? Again, there were no lightening strikes any where nearby during that period. My theory (guess really) is that the control wires leading to the tuner corroded on our wet, rough passage from Chagos to Rodrigues (that much I know to be true), and that this lead to the tuner being bypassed. Not noticing the failure to tune (a danger when tuning within Airmail, I suppose), I then foolishly continued transmitting while hunting for my Sailmail stations and cruiser nets. The frequency mismatch resulted somehow in surges at the circuit board which fried the transistor (and whatever else). Now that the control wires and connectors are all replaced and working properly, the problem should not repeat with a new transceiver. Seem reasonable?

[SoonerSailor]

If the transistor is THAT small, it doesn't sound like it is one of the final power transistors, which would see the most abuse from a SWR mismatch. John or someone may correct me if I'm wrong.

Your best bet is to send it to ICOM for service. If you need a radio sooner than you could get that one back, then buy a new one and sell the old one when you do get it back.

Another alternative would be to buy an older model ICOM SSB to fill in, or even an ICOM ham transceiver that is compatible with the AT-140.

I'm sure none of those solutions are going to be simple for you, and I wish you good luck!

Seems like you have cleaned up what you can, and I wouldn't expect a repeat problem of the same nature. It may simply have been a rare failure of something that wouldn't be expected to fail. The M802 will normally protect itself in high SWR conditions.

Chip

[a64pilot]

Try calling the guy at Dockside radio in Fl.
I have never been there just bought stuff from him and had brief telephone conversations, but it sounded like he might be the type that may have an extra xmitter laying around and or could send you a new radio?

[Auspicious]

Originally Posted by a64pilot

Try calling the guy at Dockside radio in Fl.
I have never been there just bought stuff from him and had brief telephone conversations, but it sounded like he might be the type that may have an extra xmitter laying around and or could send you a new radio?

Gary Jensen. Gary doesn't have loaner radios. You'll have to contact Icom for that.

[btrayfors]

All this long-distance guessing is disturbing to me, in the extreme. For want of a good SWR/power meter and a dummy load.......

NO BOAT SHOULD LEAVE PORT WITHOUT THESE TWO VITAL PIECES OF GEAR. FOR A TOTAL INVESTMENT OF UNDER $100 THEY ARE WIDELY AVAILABLE AND WOULD IMMEDIATELY HELP TO DETERMINE THE PROXIMATE CAUSE.

Sorry for the rant, but I'm really tired of this when the resolution is very simple and cheap.

Don't ignore the tuning/control cable. The connectors at each end are a disaster....not waterproof and very prone to corrosion and breaking when you attempt to remove them. Also, I've seen a NEW control cable defective in a NEW 802 installation in Annapolis. Apparently it was stressed too hard during installation, and had broken conductors inside. Replaced the wire and bingo: everything now worked.

Tuners do go bad, too. However, the AT140 is an excellent piece of gear and it is very well waterproofed....unlikely to be compromised inside. EXCEPT, as mentioned, sometimes the mechanical connections inside are not tight, especially for the ground.

FWIW,

Bill
WA6CCA

[SimonV]

No one has mentiond a very hidden fuse inside the transceiver. You can still buy the m802 without DSC. The radio shop in Harvey Bay Australia still has them as well as everything else. Mine had similar issues on the way from Tonga to Fiji. There was a lightning strike along way from me shortly after i could o ly use low frequencies as one panel had a burnt thing on a middle board.