AT1 Heath kit (by N5AF)

When I received Heath Kit AT-1 number 2, I could hear glass tinkling around inside the box/cabinet. I got  AT-1 number 1 going and on the air first.

I spread out a sheet of The Houston Chronicle ( Yesterday's News Tormorrow! ) and opened the case after placing the AT-1 on the paper. The 5U4 had either fallen out if it's socket or had never been there and was broken. After that mess was cleaned up, I gave it a deep cleaning, removed the old filter caps, replaced them and neatened it up a little.

The previous owner had mounted a big base with screws for the connecting wires to attach to and had an Ice Cube 120 relay mounted under the chassis for antenna changeover.

All that came out & I replaced the coax connector ( cheap plastic insulation that melted when I soldered to it. All of this in one day!

I hooked up a dummy load and a key, after finding a " new " 5U4. It tuned right up and makes plenty of power. Only problem was, the previous owner, probably to eliminate chirp, had wired the 6AG7 so that it runs full-time when B+ is on, which kinda defeats the purpose of my E.F. Johnson T.R. switch.

It will spend a week or so more on the workbench. I want to add fuse holders to the DX-20s and both AT-1s. Don't want any surprises while I have stepped out of the shack for a minute. When I was running the DX-20, I could hear the popping of the filter caps as it built up " speed " as the popping increased. The filter never blew, but it has got to be close.

One AT-1 will be parked on 3546 and the other on various cw xtal freqs that I have on 40 meters.

This one was an easy one, especially after doing the other AT-1 right before it.

73,

Sam Neal  N5AF

Real Radios Glow In The Dark (by N5AF)

Hello everyone,

I started collecting old World War II ARC-5 transmitters several years ago and now have almost a complete set of the transmitters and several receivers. Yesterday ( 3 Feb, 2010 ) I laid one of it's back and proceeded to start the conversion, as per the recent QST article in January 2009 QST magazine.

These were designed to be used as HF transmitters mainly in bomber type aircraft where there was a radio operator present  and are light in weight, mostly aluminum construction. Each has a 1626 VFO tube and a pair of 1625s in the final, capable of 150 Watts input if it wasn't for the current fuse in the B+ line. Typically, they ran about 25 Watts or less. Each covers a particular part of the HF spectrum, with several of them covering ham bands without having to change the VFO circuit any at all.

The conversion process is relatively simple. The filament wiring needs to be changed so that the filaments will operate off of 12 Volts instead of 24 Volts as was the design Voltage. Each transmitter has a calibrator crystal in it and when the VFO is tuned accross the crystal frequency, the magic eye tube closes, giving an indication of calibration accuracy. The transmitter filaments must be operated off of direct current for this feature to operate.

I now have the filaments rewired for 12 Volts DC and the long ago fragerance of dust on hot glass is perfuming up my shack with long ago fragerances I had forgotten. I removed the two relays and am wiring the rig so that the VFO runs all the time ( while transmitting ) ( No QSK ) and also providing regulated voltage for the VFO to prevent drift. The filaments have been on for a couple of hours. I hope to have B+ on the VFO tomorrow.

I had one of these back in 1958, when I first passed my General,  that covered the 80 meter band and had a great deal of fun with it with the exception of receiving a " Notice Of Out Of Band Operation " from the Canadian equilivent of the FCC. I had connected a long wire antenna directly to the plate caps with no final tank circuit to filter out harmonics and my 3700KC +- signal had a nice harmonic on 7400 KC+-.

The radios were designed for operation on aircraft that operated on a 24 Volt DC system.  It is a simple matter to rewire the filaments in parallel to operate them off of more convenient 12 Volts AC or DC.

To minimize drift, it is recommended that these transmitters be operated with the VFO running all the time you are transmitting, and that they be operated off of a regulated high voltage power supply for the VFO.

The relays in the radios are taken out and thrown away and the power plug on the back is usually taken out and discarded and replaced with a more obtainable 8 pin octal plug.

Then, all that remains is to add a key jack to plug your key in to and key the cathodes of the 1625 tubes, which are basically 12 Volt 807 tubes, and take the little variable coil and antenna changeover switch out and discard them, mount a chassis mount coax connector where the push-button aircraft 25 foot  ceramic post was at before. Total conversion time is about 2 and a half hours.

When #1 son drops by with his digital camera, I will have him make some photos for the SHARK website.

The one I am converting is for the 40 meter band. After I get it working, I will tackle the 80 meter one next. Supposedly over a million of these were manufactured during WW2. Details to follow!

73,

Sam Neal  N5AF

Rohn 35 Hazer Project

Article presented by Jeff (K5MV)

This has been a work in progress for sometime. I've been aware of hazers for years. The Glen Martin Tower Hazer is one of the most popular. I never thought about it much until John, W5JON bought a tilt over 60 foot tower about a year ago. He spent over $10,000 on tower and installation. It features a heavy duty electric screw winch that lets the whole antenna/tower down in just a few minutes. I just couldn't afford that.  With the age of hams, including myself getting older, most of us can't/don't climb anymore. I have been a slave to my antennas mounted on my tower all these years. Always having to find someone to climb and usually having to pay them. I bought the Rohn 35G tower a couple of years ago from a friend in the club from Livingston thinking I would someday either use it, or peddle it to someone else. It's generally like Rohn 25G, just 3 inches wider between legs. At the time he sold it to me he said it was Rohn 45G and I didn't know any difference. I didn't find out it was actually Rohn 35G until I helped a friend of mine pick up some Rohn 45G he bought from a ham in Pasadena.
 
I saw a home made hazer for Rohn 45G from a Florida ham selling it on e-bay. This was in August of this year. That's when the wheels started turning and I got the idea to buy or build a hazer. I found out quick that I couldn't find one for Rohn 35G. Rohn 35G was manufactured for Motorola for their communication towers. It was never sold commercially to the public. That's why you will never find accessories for that tower. No rotor plates, thrust bearing plates, hinge plates, etc. There's a lot around from hams who have taken it down in various places and resold it to others who like me, found out they had to fabricate everything for it.

It was just by chance that Jesse, KB5YC and Ron, ND5T found out a piece of Rohn 45G would fit perfectly over a piece of Rohn 35G with enough clearance to move up and down. Jesse had some 45G that was bent. We cut a 42 inch section and that became our shell for the hazer. We fabricated all the rest. Really wasn't brain surgery, just took Ron's well equipped shop, mechanical expertise and several hours of cutting and lining up everything. Now we have several others that want hazers. Imagine that? The next one we build is for KB5YC, Jesse. It  may be built from aluminum to lighten the load and no rust to worry about. Because of the steel plates, I had to coat the entire hazer with "Cold Galvanized Paint", It's the same color as the tower and looks great.

If you have any questions contact me, K5MV, Ron, ND5T or Jesse, KB5YC.

......73's Jeff, K5MV 

The Hazer is pulled up and down the tower with a hand winch with a built in brake.  This is so that if your hand slips off the handle the antenne's stay put and nothing will come crashing down.

73's Jeff, K5MV 

ND5T  "Tiny" Tower Install

My "Tiny" Tower (when compared to the the big boys like K5MV)  will be a 38', Telescoping/Tilt tower.  I will be installing a Tri-beam antenna provided by Stu (K5STU), a 2m beam, 70cm beam, and a multi-fan dipole all built by Clyde (N5IF).  The tower will have a Yaeus G-800SA  Rotator and controller for turning all the beams. 

I built the tilt base from raw steel that will allow me to lay the tower over so I never have to climb this little thing.  We installed tractor pins in the base so this is easy to work with.

Clyde (N5IF) and I started Saturday morning with the plan to install the tower base at my home. We used my Skid loader with a 12" auger and dug down about 4.5' with multiple holes. We then cleaned up the hole with a shovel and estimated we had close to a 1 yard hole. As this is a small 8” triangulated tower this would be more than enough concrete. I had previously built a tilting base plate which Clyde and I welded to a 6” square tubing about 51” long. We then added several pieces of angle iron to the post about 12” long for added support into the concrete. We put this in the hole and poured in the concrete. When we got close to the top we added a 34” square 2x4 frame to make the top look good, and filled in with additional concrete and let her sit.

Sunday morning I put the tower on the base and everything looked good. I had to cut the corners off the pieces on the tower as they were hanging on the welds of the bottom plate tabs.  The only issue I have is the bolts I used to attach the tower to the base plate have too much slop which allows the tower to be move around when it is standing up.  I will replace these as soon as I find the right bolts. I replaced the winch with a new braking winch as the existing one would not hold the weight of the top section when cranked up. I then installed a 24” crown section from Rohn 25 (provided by Buck W5EAT) onto the top rotator mount to serve as a guide to handle the weight when the tower is laid over.

10/24 - Went to K5STU and took down the Tri-Beam and started the install at my QTH.  Finished Sunday installing the beam, raised the tower to about 30 degrees to check SWR's and all looked OK.  As the CQ contest was going on I went to 15m and keyed the mic and made a contact in the Caribbean on the first try.  I shut down and tested the rotator, and stood the tower up to full vertical.  I then cranked up the tower and ended up working the contest for a couple of hours and made contacts in 18 countrys including the French Polnesia.

11/1 - I added  2m and 70cm quagi's built by Clyde (N5IF)  to the top of the tower.  The boom on the 2M is a 1" conduit so I added a 1" sched 40 PVC pipe to the mast, I then took a PVC 1" "X" and grinded out the inside so the 1" mast would slide straight through the X without stopping and set the height I wanted on the mast and put a screw through the X into the Pipe.  I took the 3/4" T on the 440 Quagi into a 1" T on the Mast (I didn't have a coupling) and tied the antenna's into a duplexer with a single run to the shack.  I tested the antenna's and could hit the Livingston repeater with 5W, from 40 miles away, the Trinity repeater is about 50 miles away and I could hit it with 10 watts, so to say the least I am very happy with my set up.

73's
ND5T