Field Power: Honda EX-1000 RF Noise Problems & Other Alternatives

UPDATED 11/20/14

Honda EX-1000 Generator: I have been running several field radio systems from a Honda EX-1000 generator for AC power. (Technically, it’s an Alternator, not a Generator and that is a significant subtlety – read on.) It’s a good “camp” “generator”, starts reliably and is reasonably quiet acoustically.

The bad news: it radiates terrible ignition noise into the radios. I had to be very careful in orienting the antenna versus the AC power line and then play with grounding – still lots of ignition noise.  Radiated noise from the ignition directly as well as conducted noise out on the power line and then back to the antennas/radios. You might not notice it when using an FM receiver on VHF/UHF – via a 120/12 V power supply – but on HF the radiated ignition noise is awful.
Curiously, unlike most small engines I have encountered, you need to run it on half-choke for at least 30 seconds before applying load or it “surges” for awhile. Not a problem as long as you remember to turn OFF the choke once it warms up.

The Honda’s have good reputations, well deserved until you try to run HF radio receivers in an RF-quiet environment. They look great until you look under the sheet metal. I specifically bought this NON-inverter model because it also has a sheet metal shell which I had hoped would help contain the ignition noise.  The newer generators have plastic covers – bad news shielding-wise.  Unfixable. They are cheaply built for the consumer mass market and in my opinion are overpriced for what you get. There is absolutely no electronic shielding or filtering in the EX1000 system. Not one lock washer under a screw to contain the ignition noise within the sheet metal and, of course, no ignition HV wiring shielding. No lock washers, even to keep it from vibrating apart.  Five cents worth of star washers would have helped considerably.  But Honda has great marketing!

That’s just cheap, shoddy construction. I had to completely disassemble the generator sheet metal housing parts (nothing fit quite right upon reassembly – sloppy tolerances – bend to fit) to see what the problems were.  I had to build up an RF shield braid system for the ignition wiring between the plug and ignition coil and ground it at both ends.  In the below photo you can see the plug-end of the shield braid and its ground bolt.  The other end at the coil is similar.  I ran a bead of solder all along the “wraps” to make it a continuous conductor but I kept it away from the plug insulator to prevent HV problems when it is damp.

Still too noisy, so I had to add torroidal RF filter chokes to the AC Hot and Neutral power wiring up to the connectors and add a bunch of external-tooth star washers to keep everything properly grounded. Much scraping of paint from surfaces that need to be in electrical contact. Honda didn’t bother with any of that. My modifications made about a 20 db improvement in radiated noise on the HF bands but incurred an expense/improvement that Honda felt the average homeowner would not even notice, much less appreciate.  Most people just seem to care that they start easily, forget about the actual underlying engineering/quality. But hey – that’s their market. The wonderful world of tradeoffs in engineering cost economics.

Also, curiously, the “stock” generator AC output voltage falls to zero – while the engine keeps running – when I connected an RFI filtered power strip to the output.  ( SL-Waber “Wave Tracker” 120 db isolation filter) What?? That was an earlier attempt to suppress the conducted RF noise.  The strip contains series/shunt RF filters as part of its construction.  (Spike L-C suppression in the power strip – not MOV’s).  Remove the power strip, all is OK.  Huh?   I put the same strip on my Jacobson PU-181 Military generator or on either of my “inverters”, no problem. Apparently the voltage regulator/excitation system in this generator does not like any serious inductive power factor in the load at harmonic frequencies – even though those series impedances would be very small at 60 CPS.  It powers an electrical drill OK.  The generator apparently shuts off its capacitively-tuned field current when loaded under this circumstance. Great for powering simple lights or appliances, but beware if you want to power radio gear with it through an RFI filter network.  Weird…..
The new, plastic-cased (unshielded), even cheaper-built generators use power “inverters” to make AC from DC from AC so I specifically avoided that technology for my applications. Not sure what the waveform looks like but I wouldn’t be surprised if it’s “nice looking” 60 cps sinewave (with lots of nasty RF hash being generated at zero-crossings, digitizer trip-points, or worse.) Those machines are basically gas powered, big Analog-to-Digital-to-Analog converters. Mr. Fourier tells us that all those fast conversion step-functions contain LOTS of high frequency noise stuff too. Smart guy!  But that radiated ignition noise is very bad, probably Unfixable, zero shielding.

Honda’s marketing slogan is aimed at the average homeowner/housewife whose only indication of “quality” is easy starting. “The One Pull Honda” LOL. That easy starting (important) is facilitated by a high energy ignition system (good) but that comes at a steep price (bad) – very high radiated ignition noise (a show-stopper for me, but invisible to someone running some lights during a power failure).

Now on to the “Inverter” technology: The common mode broadband hash on the power cable is particularly bad with this EU1000i generator – Mama Mia!  Easily verified by running battery operated HF gear nearby, then connecting/disconnecting the power extension cable (antenna) at the generator end. Big difference in the 80/60/40/30 meter bands anyway. This one will take a lot of common mode power line choking to beat it down. Honda Fail – but their competitors are probably no better in this regard.

Honda eu1000i Inverter RF Noise Generator

Above: My buddy’s Honda EU1000i “inverter” generator to power his off-grid cabin (and ham radio gear in the cabin).  A nice small generator; it starts reliably and seems to be fuel-efficient and is much lighter and quieter acoustically than my EX1000. However it radiates LOTS of ignition noise, much worse than my unmodified EX1000.  We have to charge batteries with it, shut it off, and then run the radios off the batteries so we can hear HF signals when we are up there. (note the kerosene lanterns for lighting during Radio Ops.)  It’s cheaper for Honda to build it with the simple inverter circuit board than to build a true AC sinusoidal alternator machine – the average homeowner would not realize or appreciate the difference. “Designed by accountants”. A decent “cabin generator”; they put some money into the muffler system design – it is very quiet. But again, Radio Ops beware!

Fun Fact: When the Zombie Apocalypse goes down, all those “inverter” generators are Toast at the first EMP burst. Those long extension cords make wonderful antennas connected directly to all that computerized inverter circuitry! Just when you need the generator the most: (SNAP! Smoke! what just happened? !!)

Honda Eu-1000i Powering a GRC-109 and killing the receiver

Honda Eu-1000i Powering a GRC-109 and killing the receiver

Above: Giving it another try, this time powering a GRC-109 at a remote campsite. Awful ignition noise competed with the many CW signals we were hearing. At the end of a 100 foot extension cord oriented at right angles to the antennas it radiated a lot of ignition noise. Inserting the SL-Waber 120 db common mode noise filter at the generator made a barely noticeable difference despite trying different filter-generator “grounding” schemes. These generators start easily, primarily due to their high-energy ignition systems – but you pay the price. With the plastic case there is no real way to shield it. The next project is to tear it apart and try to shield the ignition system and wiring and install inductive chokes in the AC output lines like I did with my EX-1000. We’ll see.

Incidentally, inserting the SL Waber Wave Tracker EMI filter at the output did not cause the generator to stop producing AC like it did with my Honda EX-1000. Different exitation scheme that is decoupled from the load. At least THAT worked…..

Anyone else have any experiences with those powering HF receivers in the field? I guess I am just spoiled by using well designed “military grade” hardware rather than “consumer grade junk” that is on the market these days.  But then again, it was “cheap”.

PU-181/PGC-1 Generator: Below is a photo of my favorite vintage generator (alternator).  It is the PU-181/PGC-1 built in 1950 by Jacobson of Racine Wisconsin.  TM11-943 applies. The PGC-1 was a field teletype system utilizing the TT-4(*)/TG  Teleprinter system for wire-comms in fixed or tactical forward areas.  Since the generator puts out 300 watts at either 120 or 240 VAC I’m sure it was used for every other sort of military need as well.  These things would be very handy. It is a 2-cycle engine generator, requiring oil to be mixed (16:1, SAE 30 above 32 degrees F) with the gasoline to lubricate the working parts.  The engine develops 1.25 horsepower at 3600 RPM. It is very reliable and starts with the first pull, even after sitting idle for over a year.

The TM states that it will run for 7.5 hours at the full 300 watts output on one tank of fuel. When powering my military radio gear in the boonies running casual operations it will go for over a week on a single tank. Fill it up and go….no need to bring the Jerry can.

Except for a standard AC power connector which I installed, this generator has all the original parts from when it was built. Including the spark plug. It has a lot of mileage on it but still runs great. You just need to clean the carbon from the exhaust port every 5 years or so. It even runs fine on year-old gas. Dependable.  I understand that an Autolite Part Number 2246 shielded suppressor spark plug is a good replacement if needed.

It’s a little noisy acoustically, sounding a bit “rattle-y” and it produces a bit of white smoke from the lube oil, but not enough to be a tactical observation concern.  Its principal attribute however is its very effective RF shielding to keep nearby radio systems happy.  The entire ignition system, including the spark plug is completely shielded. Lock washers everywhere. This thing is very quiet RF noise emissions-wise, a perfect campsite generator for field comms work.

PU-181 Generator to power the RS-6 Radio Set

Above: The PU-181 as set up ready to power the RS-6 HF CW radio in the boonies. Way more power than the RS-6 needs but you can also run the Blender at the same time.

There is another very similar generator for the GRC-9 and SCR-284 (PE-162* depends upon the model) that looks almost identical but it has an outlet box specifically to power that radio – I believe 120/240VAC is not available. The PU-181 will run all day on a tank of gas with a pretty good load. It will run all weekend with the type of radio comms I usually have going – it sips gas.

PU-181 Generator in the bush

Above:  The PU-181/PGC-1 generator doing its thing out in the boonies.  No problem with high altitude.  Only a slight adjustment of the voltage control knob (feedback to engine speed) needed at 8000 feet elevation.  Still started on the first pull after a year in storage – with old gas to boot. (Hint: Use the longest starter rope you can get on the shaft winder. 550 parachute cord is ideal. That long rope really gets the RPM up for awhile and the engine can’t help but start!)

PU-181/PGC-1 Gas Generator

PU-181/PGC-1 Gas Generator

Above: The PU-181 cranking out Watts to power my RS-6 radio at FOB Long Rock.

The Put-Put 2000: Of course if you are in an “Improvise, Adapt, Overcome” situation and just need to generate up to 1000 watts of power to charge 12 volt car or deep-cycle batteries, the below item might be useful. Powered by an ancient Briggs and Stratton 2 horsepower lawn mower engine, it drives an automobile alternator. The engine came from a beat up, old yard-sale lawn mower that I used to cut the grass for an additional 15 years. Mower wore out, engine kept on running. It never made it to the Go Kart I had envisioned.

The alternator is rated at 63 amps and there is more than enough engine power to produce that. The alternator internal voltage regulator holds the charge voltage at around 14.7 volts; when the battery rises to this voltage the field winding current is automatically reduced to prevent overcharging.

This is a new and improved model of the earlier PutPut 1000 that used an old relay-type voltage regulator. This version features a Delco Remy alternator with the built-in voltage regulator for improved reliability. With the belt ratio chosen, the engine runs at low speed but it still sounds like – well – a lawn mower – perfect acoustic camouflage for your clandestine suburban operations. The pulley ratio chosen also prevents the engine from stalling if the load suddenly increases – not much of a flywheel here….It includes a field current switch to shut off the field winding for easy starting (your rope pull does not also generate power) and an external Ammeter. (Yes Virginia – it does radiate a lot of ignition noise!  But you are not playing with radios while you are mowing the lawn, are you.)

This contraption sits on a 3/4″ plywood base on 4 pieces of 1 inch rubber coolant hoses, split and bolted to the bottom for vibration control. Simple, effective, does the job. Made in the USA !
Introducing the new and improved “Put-Put 2000″ from Hillbilly Engineering.

From Murphy’s Laws of Combat: “If it’s stupid – but works – it isn’t stupid”

A belt guard is next.

Below, here it is earning its keep.

Lawn Mower Generator charging 12V battery

Lawn Mower Generator charging 12V battery

STILL needs a belt guard!