propane conversion or natural gas conversion for small engines

this page is to document a very interesting setup my father in law
Donald fabricated to convert small gasoline engines to run on
natural gas or propane.

Sadly Donald passed away a some years ago now and his collection of small engines has been sold and scattered to the winds
but perhaps some people will find the simple technique he used to make them run without having to mess around with messy gasoline interesting for academic purposes although i do not recommend using it as there are proper kits available and this settup is not safe for unattended operation.

To convert 1-5 HP gas engines to natural gas or propane he modifies a poppet regulator (Maxitrol RV48 works well)
by removing the pressure regulating spring and cap. disassembling and replacing the diaphragm with a piece of a latex surgical glove to get the regulator
to fully close but still open under vacuum .  That way if the regulator is oriented up side down so that gravity helps hold the diaphragm valve closed no gas will flow until vacuum created by the engine sucking air through the venturi draws the gas through the regulator.
for use with LP gas he puts a gas grill type regulator between the tank and the modified poppet valve.

poppet regulator

Next he constructs a venturi using copper water pipe brass shim stock and 3/16” O.D. thin wall brass tubing.

he selects the size of copper pipe that best fits over the air inlet of the carburetor on the engine and cut a piece 2” long.
(¾” rigid copper water pipe seems to work well for most small engines.)
then he rolls 2 pieces of shim stock into cone shapes about 1” long with the large ends being the same size as the I.D. of the copper pipe
and the small ends being between 5/16” and 3/8” larger
for larger engines smaller for smaller engines but 5/16 to 3/8 seems to work well for most small engines.
He Solders the 2 cones inside the 2”piece of water pipe so that the small ends meet in the middle
then drills a 3/16” hole though the side of the water pipe and though the shim stock just to side of were the 2 cones meet
so that the side of the hole cuts the edge of one piece of shim stock .

Then he cuts the end of the 3/16 O.D. brass tubing at a 45 degree angle.
Then inserts it into hole in side of water pipe aligning it so
that the angle cut lines up with the angle of the shim stock as best he
can and solders it in place.

next he fabricates a flow valve to go between the poppet regulator and
the venturi by drilling and taping a hole for a small machine screw
into one side of a piece of tubing so that when the machine screw is
screwed all the way in till it touches the other side of the tube it
pretty much blocks the entire tube. that way he can adjust the fuel air
mix by turning the screw in or out.

then he plumbs it all together with assorted tubing and hose in this
order, gas grill regulator (only needed for LP), modified poppet
regulator, flow valve, venturi. and then mounts the venturi on the air
intake of the carburetor of the engine being sure to get a relatively
air tight seal between the venturi and the carburetor.


this is posted for academic purposes only if you choose to use this information you do so at your own risk and I will not answer questions on this subject thank you.

the redneck dipole.

this is how i built my first antenna for HF its quick and dirty keep in mind that if you want a dipole that is going to last years and years do it the right way with a proper balun center insulator and proper end insulators but as a new ham you most likely will be experimenting with many antennas and moving through them quickly so it makes no sense to spend a huge amount of money on each one.

If you have some way of checking swr so you can tune the antenna then this antenna is a breeze allot of your modern radios have a swr meter built into them if your running an older rig like me then your going to have to beg, borrow, or steal a swr bridge when i built this antenna i borrowed one from a local ham and he ended up letting me hold on to it as a long term loan sorta deal.

anyway what your going to need is a so-239 panel mount a machine screw and nut to fit one of the mounting holes in the so-239  i small piece of rigid plastic i used a piece of the lid of a tidycat bucket about 3 x 3″ square this will be your center insulator . your going to need some insulated wire most any wire will do you can get 75ft rolls of 2 conductor 20 gauge speaker wire for less than $10 you can measure out enough for 1 side of the antenna cut it then split the 2 conductors apart use one conductor for each half of the dipole

this dipole can be made for any hf band within reason using this calculator  20 meters for a first antenna for a new general be a good place to start  or 10m for a tech looking to get on the tech portion of 10M

dipole calculator

use the dipole calculator linked above to decide how long to make the wires make sure to make your initial cut long because you are going to tie the wire though holes in your center insulator then attach the wires to the so-239 one side with the bolt the other side will have to be soldered to the center pin.

because the wire is insulated we do not need end insulators just bend the wire over in a loop and tie non conductive rope to it. believe me i had this antenna up an entire winter swr never changed.

calculate your antenna long to start and shorten equally on both sides until swr is good. word of warning though if you have more than a couple feet of wire bent under and the end not shorted back onto the main radiator say for instance you built it for 20M but you want to experiment with 17m so you try to shorten the antenna by folding the extra wire under. well i tried that and after a certain point swr goes crazy unless you strip a bare spot in the main wires and short the ends of what is folded under to it.

you will need to wind a 1:1 choke balun in the end of your coax to do that measure out 10 feet of coax in the end of your coax a few inches from the connector were it connects to the antenna then wind that 10′ into 7 equal flat coils and tape it up make sure the the end of the coax going to the radio and the end going to the antenna are on opposite sides of the coil and do not touch. this is directly out of the aarl handbook 2004 edition. this will work with rg-58 rg8x and rg-8 coax and is multi band but works better on  10m-20m i am told

as far as coax if your building this for 10M get good coax but for 20m or 40m if your on a budget rg-58 will work on 20m over 100′ of rg-58 would be about 1.4db which means your getting 71watts to the antenna stepping up to rg8x would only get you 4-5 extra watts at the end of the cable on 20m and rg8x is twice the price usually.

the cheapest way to get coax is to buy just the coax no ends and buy solder on pl-259 ends and adapters then find a local ham to teach you to solder them on. or you can buy a crimping tool and use crimp on ends.

if your going to leave the antenna out in the weather tape the so-239/pl-259 connection with the weatherproofing method of your choice. electrical tape will work fine for the short term.

best how to solder pl-259 connectors videos end insulatorbalun

this is a description of how I started out in ham radio on the cheap.

when i passed my technician test one of the friends of mine who talked me into becoming a ham KF5IXZ Marty (now silent key) sent me a used Kenwood 2m business band radio that was supposed to be preprogrammed for my local repeaters but the person who programed it for him reversed the transmit tone and the receive tone so therefore i could hear nothing and no one could hear me. he also sent me a 1/4 wave ground plane antenna he had built. those radios are channelized and only programmable with the proper software and cable. so wile i was hunting down the proper cable and software to correct the programing in that radio i went ahead and ordered a baofeng uv-5r and a programing cable.  those radios were just becoming common at that time cost me about $35 shipped. and got on the air with that

eventually i tracked down the proper cable and software for a price i could live with and got the kenwood radio reprogrammed

i already had an old 10 amp radio shack power supply the older transformer type from a previous project but it had been in storage for the last 15 year and the capacitors had dried out and it would not hold voltage at full power so therefor i wired a 7ah SLA battery i had on hand to the power supply then connected the radio to that it just acts as a big capacitor keeping the voltage from dropping to low when i transmit. combine that with a 20 foot coax cable from radio shack and i had a working 2m station.

in that time frame somewhere i ran into mike who had also just got his tech he was one of the first KD9 callsigns in our area and i was one of the last KC9 we kinda drawn to each other because we were both newbies and liked to talk he has since moved out of state and changed his callsign but we still talk over Echolink almost daily he has his extra now and is in a very active area for ham radio.

2m and 70cm are not really active here in my area. so Marty and my other elmer Scott H as well as members of the local club pushed me to get my general and move to HF

so i  passed my general then the question was how to afford a radio we had just bought a house in Dec of 2013 just after i got my technician license and at that time every Penney counted but eventually i got a refund for the money i had to put in escrow to guarantee that i would complete the painting and repairs to the exterior that the FHA required (little tip if your buying a repo house through the FHA buy it in the winter after its to cold for exterior painting that way if the FHA inspector requires any repairs or painting to the exterior you can just put money in escrow then complete the repairs and painting yourself after the sale in the spring and then get your money back if you buy in the summer they will force you to pay to have it done before closing)

after a long talk with my wife think on my knees begging it was decided i was allowed to use $500 of that refund to buy a used HF rig

after a couple local deals that fell through my elmer Scott called and informed me that Associated Radio in Kansas had a used Kenwood TS-430s for sale on there website for $450 that would make a really good radio for me Scott was familiar with that business as it was local to him and he had dealt with them numerous times.

Marty pointed me toward a surplus 25 amp switching power supply that was available at the time for pretty cheap that him and his friends had been buying and had proven to be free from electrical noise that plagues most cheap switching power supplies

by that time my elmer Marty KF5IXZ had been diagnosed with leukemia so i bought 100 feet of RG8X equivalent coax from a local electronics wholesaler and some solder on pl-259’s and adapters and a so-239 chassis mount.

i had Lowell who is a local ham but he is not much into talking on the radio he mostly builds and fixes stuff he showed me how to solder the ends on.

then i used a spool of old copper wire left over from my fathers hvac business along with that 20-239 and some cloths line rope to make a 20M dipole Lowell loaned me a radio shack SWR meter for HF that allowed me to tune the antenna i was able to make contact and talk with Marty on 20m SSB a couple times before he died over that piece of wire.

bartered for an older copy of the AARL handbook and in that handbook is how to  wind a coax balun in the end of your coax for a dipole when you do not have a regular balun that info is also available online

i made a number of contacts with that antenna it would have worked better if i had been able to get it higher i only had it about 15 feet off the ground. i shortened it to 17M for a wile and made my first contact to outside north America on that it was to Costa Rica

eventually i found a used antenna tuner. again out of the used section of associated radio it is a mfj-901 not the B model but an original 901 i do not remember what i paid for it but it was cheap enough that i jumped at it when i saw it on there site. it was under $50 and it has works very well.

having an antenna tuner allowed me to start contemplating a multi band antenna and after thinking long and hard about what i could do cheaply that would be reasonably effective i decided on a coax fed end fed random length antenna using a home made 9:1 UNUN you can see a photo of the waterproof box i used to hold the UNUN below you can see details about the antenna here.

after the 2015 field day i was determined i wanted to try digital modes so i did allot of research into different sound card adapters and settled on the easydigi with usb ptt  which cost $50 specifically set up for my radio with everything needed to make it work. all the cables everything.

i use it mostly for psk31 which i find very enjoyable but i have also set up and experimented with winlink with it as well as a couple other modes.

radiotesting2 antenna2 0910151332 0910151712a