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Weird 817 behaviour

This has happened twice.

I reconnect the 817 in the mobile-mount position in my car after an activation. I check it is receiving a voltage >12 (which indicates it is running off the car battery as intended) and set 2m to the rear antenna connector (it is usually set to the front terminal for an activation). I then turn the 817 off while I start my engine. I turn the 817 on again, but find that none of the buttons (band/mode change, F button, V/M etc) work. Only the rotary controls and the on/off button works. No procedure (turning off and on again, disconnecting and reconnecting to car battery etc) rectifies the problem.

Turning the rig off and leaving it off for an hour or two, then turning back on, and everything works normally again.

The first time it happened, I wondered if cold/damp had got into the rig and it needed to “dry out”. But the the second time, it was actually after running the rig in a scout hut for JOTA! And on both occasions, the buttons all worked when I set antenna connectors etc after reinstalling into the car. They just then didn’t after starting the engine! (But did a couple of hours later).

Confused. Any ideas?


In reply to M1EYP:

I have had the same on the mountains when its powered by an external battery. I have to force a reset to get it to behave when on a mountain because I cant wait for a self reset.

It has only done it a few times in the past and since then I have made some changes in the software and the problem has stayed away.

In reply to 2E0KPO:

ISTR the PA devices are always powered in the 817 with the power switch controlling the processor and small signal stages. That means it’s possible for any large transients on the power supply when starting the car to still get to the 817. Depending on the circuitry it may that the transients if they are big enough are enough to upset the processor.

If you have the car power feed for the 817 not switched but run straight to the battery then any starting transients will be seen by the 817. You may want to fit an isolating switch so that you can hard disconnect the 817 when starting. If it is connected to a feed from the car fusebox then it should be disconnected when the starter is engaged (on my Honda all the accessory feeds go off when you crank the engine) and it maybe pickup of local EM disturbances via the power cables.

Steve’s case when connecting an external battery on a hill is much harder to explain.


Yes, the power feed runs straight from the battery. I have had exactly the same configuration from over 6 years, swapping the 817 between car and rucksack before/after activations. I have occasionally had a problem when reconnecting the power jack to the socket at the rear of the 817, but this has always resulted in a fuse popping - I have inline fuses on both sides of the power feed line.

Strange that problems are only happening now after all this time, unless my ageing car is emitting more rubbish when firing the ignition.

Thanks for the suggestions.


In reply to M1EYP:

I’m surprised that any of the connections on a piece of consumer grade equipment would stand up to 6 years repeated connection/disconnection! My appreciation of Yaesu quality has gone up quite a lot!

If you aren’t running HF mobile wouldn’t a secondhand mobile setup be a lot less grief? Either one of the myriad dualband FM units that frequent the “for sale” pages of Richard’s website or eBay. Or if you do run SSB mobile either a TR-751e or even an FT290 and an MM amp. Or burner as those of the chickenbox fraternity would say :slight_smile:


Hi Andy,

I do run HF mobile when 10m is open, and occasionally other bands when I bother to change the aerials over.

I admit to having the power socket repaired - once.

I like the convenience of having my 817 trickle charging between activations. I have SLABs, but TBH, don’t really need them because I easily get 4 hours out of the 817 internal pack after it has been topped up on the trickle charge.

I do like the 817 as a mobile rig, and I guess after 7 years I might just be a bit “stuck in my ways”!


BTW, just had a “817” from the staffroom coffee machine - extra white, whipped, no sugar.

In reply to M1EYP:

4 hours out of the internal pack? That’s impressive, I seem to get rather less. I have an extra battery pack, simply a holder for 10 AA NiMH’s. Does have rather more internal resistance than is ideal (as seen by voltage drop when transmitting), but it works decently and a lot cheaper than SLAs.

4 hours out of the internal pack?

Yes, it’s the OPP817 pack from One Plug Play, 2.7Ah.


In reply to 2E0KPO:

In reply to M1EYP:

It has only done it a few times in the past and since then I have made
some changes in the software and the problem has stayed away.

Hi Steve,

Am I to understand you have been hacking about the 817 firmware? Would you care to elaborate?



In reply to M1EYP:
Hi Tom,

Only just picked up on this thread. Most modern rigs, especially Yaesu, have their microprocessor running at all times when power is connected. The Icom IC 706 even has a relay which you can hear click over when the power is connected. Most manufacturers, but not as far as I know Yaesu (usual caveats), have some sort of protection fitted to protect their rigs against reverse polarity and overvoltage which in many cases is simply a 18 volt zener diode across the power supply leads.

When cranking a car it is quite feasible for pulses of around 600 volts or even much more - yes six hundred volts - to appear on the power lines. We had innumerable problems when I was with Racal doing vehicle radio fits because of this; goodness knows what this sort of voltage does to a microprocessor rated at about 7 volt maximum on its reset lines!

Moral - buy a big fat zener diode and put it across your rig power input lines (after the fuses) and then fit the rig in the car. In fact do this on any rig that is run off an external supply as I have found that 24volts applied to an FT857 tends to blow things up (terminally).


Barry GM4TOE

There is another solution which I have used for many years. Have a second battery in the car and run your mobile radios off that. It has the additional benefit that you don’t suddenly find that you can’t start the car. I don’t tow caravans, but I do tow trailers, so when I have the lighting socket installed on the towing hitch, I always ask for the same a a caravan tower would have and get the installer, to loop an internal cable off the circuit and run it to where I intend to install the second battery.

As I drive diesels these days, I have a conventional car battery for the ‘spare’ rather than a ‘leisure’ battery and have been glad to jump start myself on it on the odd occasion when starting has been problematic - not due to radio activities though!

73 de Peter G0FIM / AA3JN

In reply to G0FIM:

I do the same Peter,

I used to have a car bettery behind the passenger area but considered it to be a safety hazard in an accident, now I have a 12AH wheelchair battery strapped down inside the spare wheel.

It also has the advantage of reducing the voltage drop seen by the radio on transmit if it was run directly from the car supply.

For charging I have tried paralelling it with the car system but it introduced a lot of noise, then I tried a smart charger but that made 20m unuseable, My current solution is to use a ‘smartcom’ volt sensing relay. This prioritises the car battery and then charges the accessory battery when the system rises to 13.8V (or 14V I’m not sure without checking) like a split charge system without the 0.6V voltage drop.

I have been very happy with this system, the only modification needed was to add a large capacitor near the relay on the ‘car’ side to stop it chattering when running 100W on SSB. Not an issue with an 817 :slight_smile:

Richard M0EIQ