Archive for the ‘HamRadio’ category

SWR

January 15, 2010

After very carefully tuning both the vertically polarized four element moxon and the horizontally polarized seven element broadband beam, I installed them onto the stub mast and mounted them on the main mast through the thrust bearing and into the rotator.

The mast was cranked back up to full height and the antennas were tested. I was more than a little dissapointed in that they both showed fairly high swr.

I learned a long time ago that when things don’t work out like expected its time to relax and sleep on it.

A couple of days after the initial test I took another look at the setup in the shack. I had built an antenna switching system so that I could use one run of RG8 for either the vertical or the horizontal antenna. I was only intending to use one or the other at any given time so a switching system seemed ideal.

As I investigated the hookup I found that the SWR meter was in the antenna side of the switching system. This meant that the power running the switching system was being run through the SWR meter. I relocated the SWR meter to be in line in the section running from the 2 meter rig to the antenna switch. The SWR on both antennas is now as should be.

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Buying used Radios

December 24, 2009

My recent experience with the Drake TR3 brings to mind some less fortunate experiences.

I have always regretted selling my old, unwanted radios. I never sold anything that was not in prefect operational condition. Unfortunately I cannot say the same for stuff I have purchased.

This includes stuff purchased from dealers.

In general, hams dont sell stuff that works. Those used offerings on the hamfest benches are there because the owners do not want them. Depending on why they are not wanted may effect your desire to own them. My experience has been that most used stuff is problem stuff. This is particularly true if the equipment started out in kit form.

I have seen far too many Heathkits that were built by folk who could not read or solder. By read I mean understanding the thoughts generated by the words presented. Just mouthing words without comprehension is not good enough. There is a huge difference between building a radio and assembling a kit. Not everyone recognizes that difference.

Commercially assembled radios do not always escape the wrath of the uneducated operator. This is especially true of rigs that run on the hairy edge of specifications. Used Linears and transmitters that use sweep tube finals are almost always shot before they hit the hamfest tables.

Beware of the seller who claims ‘it worked the last time I used it’. Or, ‘I don’t know its history, I am selling it for a friend’. Or, ‘This is part of an estate sale’.

The only thing a buyer should be interested in is if the radio is working now. You cant take the word of a seller who does not know what ‘working’ is. If you cant power it up and check it out yourself before purchase all you can offer is salvage value.

If you are not sure what ‘working’ is, you might want to enlist the aid of a seasoned ham who is more knowlegeable about such things. I am not saying that everyone is a crook. Some people are just ignorant. It is up to you to make sure someones ignorance does not end up costing you money and ruining your day.

The reason my recent TR3 purchase was an uquallified success is because I paid salvage value. The seller presented it as a parts radio and only requested salvage value. In short it was an honest deal. No one was trying to hood wink or cheat. I am not saying that you will always be cheated at hamfests but the opportunity for dissappointment does present itself all too frequently.

Just because you buy from a dealer does not mean you are getting a fair deal. Many years ago I took in my SB-102 as a trade-in toward a pair of used Drake twins. The sales guy at the dealers checked out my SB-102 and wanted to dock me the price of new finals because it only put out 50 wats on ten meters. I showed him that the Drake rig only put out 50 watts on ten meters as well. That shut him up and convinced me that the place was crooked as a dogs hind leg. I still went through with the deal but I never went back there for anything again.

Drake TR3

December 24, 2009

I dont need a new radio but sometimes it is nearly impossible to ignore a good deal. The TR3 was advertized as a parts radio. The asking price was $25 and the seller was local. No shipping. I could go pick it up.

So I did.

Parts radios dont work. Moreover, some parts in parts radios dont work either. The trick is to only use those parts that do work. Sometimes having a parts radio is not an advantage because the part you need to repair the ‘real’ radio is also bad in the parts radio.

In my case I wanted to repair the parts radio. Not that I needed another radio but a working radio is better than one that is broken. Besides there is little to compare with the aquisition of a new toy to inspire one to action. A working TR3 would be a real asset in that it provides 300 watts PEP. At that power level a linear might not be needed.

This TR3 was missing a couple of 12AX7s, all three finals, and an audio output transformer. I had saved the audio output transformer from the R4C when I converted it to solid state audio. That transformer works just fine in the TR3. A couple of 12AX7s were salvaged from an old strip chart recorder amp and we had noise coming from the speaker attached to the TR3.

Trouble was the noise did not change in pitch regardless of how much the tuning knob was turned. I finally discovered that the linear mechanism of the VFO had been moved past the stops and was no longer engaged in the tuning screw. Perhaps that was done to gain access to one of the screws that held the old output transformer. I got it tracking again after an hour of fiddling. It did not appear to require any alignment. The receiver was picking up plenty of signals.

12JB6s are still available at around $30 each. So much for inexpensive sweep tube finals. I never did care for sweep tube finals. Every Drake transmitter I ever had has been converted to use 6146s. The conversion is a simple matter of changing out the tube sockets, setting the bias level and neutralizing the finals. Current maket conditions have the 6146s priced around $30 each as well. So if you are missing the finals and dont have any spares, it would make sense to spend the money on 12JB6s and avoid the extra work in modifying to 6146s. In my case I had a supply of 614s so it made sense to use them.

The TR3 uses a 12 volt filament system. Tubes with 6 volt filaments are wired in series to work off 12 volts. Careful attention is paid to make sure that series connected tubes have equal current requirements so that all tubes get the filament power they need. You cant hook three 6 volt filament tubes in series to work off 12 volts. My solution to this problem was to run the three 6146 finals off 6 volts. I did that by reassigning the speaker lead to the power connector to carry the 6.3 vots AC. Not sure I like the idea of a speaker lead coming out of the power connector. Seems like an accident looking for a place to happen. A speaker can still be conneced through the phones jack on the side of the radio. That is another sore point. Side mounted phone jacks and controls are fine if you dont have any other equipment but they get in the way of everything else you want to set adjacent to the TR3.

More knowlegeable readers might point out that there are 6146 style tubes that have 12 volt filaments. The objective here was to economize by using parts on hand. After spending all of $25 for the radio I was not interested in spending another $100 to make it operational.

I did end up spending another $25 on paint, resistors, capacitors, and a decent soldering iron to convert and restore the TR3 to an operational condition. I already had an AC3 powersupply to run the T4XC. I used it to check out the TR3 but ended up building a special supply for the TR3. When you do specials like that you can design for optimum preformance. Drake only supplied 650 volts to the plates of the 12JB6s. 6146s are prefectly happy with 700 volts. I ended up running the 6146s at 750 volts. That is a little over 400 watts PEP. This little rig puts out a respectable signal on 75 meter SSB without need to run a linear.

The paint I used was Rustoleum semi gloss black. I bought two cans but only needed one can to do the job. Sanded all the scratches out with a power sander. Grey primer. The primer is not really needed but it sands better than the finished coat. You want to sand the primer to get a smooth surface. Then three very light coats of semi gloss black and the cabinet looks like new. Rustoleum semi gloss black is not an exact match for the original Drake color but we are not doing a touch up job. We repaint the entire cabinet so the color matches perfectly.

New resistors and capacitors make the conversion easier. While it is possible to salvage the resistors and caps from the old sockets, new parts are only 12cents each and are easier to use.

12JB6s only have one cathode pin. 6146s have three cathode pins. I suppose using one of the three would suffice but we ended up using all three. The cathode resistor used by Drake is 15 ohms. We used three 45 ohm 1 watt metal film resitors per tube and tied the other ends of the resistors to a #12 solid copper wire bus to connect all cathodes together and to the RF choke at the far end of the final compartment.

Screen leads were bypasse to ground with .005 ceramic 1KV caps. All three cathode pins were bypassed with 450 pf 1KV ceramic caps.

The original screen resistors were 68 ohm half watt carbon. One of them was open. I replaced all three with 68 ohm 1 watt metal film.

The new tube sockets I used did not require any modification to the tube socket holes. Make sure you use octal sockets that fit a one inch diameter hole. I did not even try to use the captured nuts that Drake used to mount the novar sockets. 4-40 hardware works fine. Use locknuts or paint the treads with nail polish to keep them form coming loose. When selecting octal tube sockets make sure they have a decent mounting ring. You will want to solder to this ring to terminate the ground side of the bypass capacitors. You also need to solder the ring at one point (or more) to the copper plated chassis to make sure you get really good electrical connections.

Mount and solder as many parts as possible to the tube sockets before mounting the tube sockets in the radio.

Note that the novar socket mounting rings were sldered to chassis as well. Save the noval sockets. I have about a dozen noval sockets in the junk box. I am savng them in case I find a stash of sweep tubes. More importantly, they can be used to reverse the conversion to 6146s should the need every occur.

The original grid connections were done using a brass strip. That same brass strip was reinstalled by soldering it to pins 5 of the 6146 sockets. It is not as neat an installation as the original but it is perfectly functional.

So now for $50 dollars and a week of light part-time work we have a new radio. Hard to believe that this thing sold for $550 when it first came out in the early 1960s. Estimates have that $550 equal to $3700 in 2009 dollars.

This TR3 is 40 years old. I doubt that it had any tubes replaced in that time. Those that I replaced were to populate empty tube sockets. There is no reason to believe that this thing will not work for another 40 years. However by that time replacement tubes might no longer be available. They are scarce and expensive even today. So it might be a good idea to set asside a stash of spares for future use.

I would be happy to let this thing go for $300 complete with power supply today. Once I get attached to it that might change.

Hold on a minute. Lets see. I have about $100 in parts in this project including the power supply. I also have about 20 hours time invested in this thing. Twenty hours taken over $200 is $10 an hour. I would not be happy working for minimum wage. No, I would need at least $700 for that TR3 and I dont know of anyone willing to pay that. Guess I will just keep it. Looks like I am already attached to it. Might donate it to a worthy cause and claim $3700 for tax purposes. Its not my fault that the dollar lost its flavor since 1960.

A word about restoration. Some folk view restoration as a knob polishing excercise. They take great pains to clean and polish to make the rig look like a new penny. I have nothing against polishing and cleaning as long as it does not interfer with operation. If the radio does not work no amount of cleaning is going to make it useful. Junk is junk regardless of how clean it is.

This project resulted in a radio that is not spotless or shiney but it works as well or better than when it was new.

The Price of 12 extra feet

November 15, 2009

I recently sanded and painted my auxilliary tilt over mast. This started out as my first and original tilt over mast about 30 years ago. Yeah, we have been in the same place for over 30 years! We like it here.

The original mast became an auxilliary when the neighbors tree got large enough to interfere with the masts function. When you can’t tilt the mast up and down without the tree branches shredding your antenna, it takes all the fun out of having a tiltover feature.

This thing was designed to tilt over toward the north. If it were not for the air-conditioning unit sitting on a concrete slab next to the base of the mast, I could make the thing tilt over toward the south.

Naw, that would mean I have to screw with moving the condenser unit. I could do that. I could even make a new concrete base for the thing. I could also end up chasing freon leaks for the next ten years.

Come to think of it, that thing does not need to be sitting all the way on the east side of the house where no one can see it (or hear it). I could move it to the patio. Shorter pluming to the A-coil, less of a cable run for electrical power, and the thing would be sitting in the shade for most of the day.

Naw, maybe in an other life I can do that. Right now I don’t need to be looking for work I don’t have time, money, or energy to do.

I can still put up beams at the 30 foot level and miss the tree but anything higher gets shredded unless it is just plain mast extention or vertical or J-pole. (I guess a J-pole is a vertical.)

No, I have not discussed the tree with my neighbor. He is hard of hearing. Just like my mother-in-law. The heaing impared sometimes take advantage of their handicap by becoming selectively hearing impared.

I am sure my neighbor would not be interested in selecting which limbs to cut and how far up to prune an otherwise beautiful 50 year old oak. Besides I am not interested in spoiling the looks of the tree either. That is why I put up a new tiltover mast 20 years ago.

Still, it is difficult not to try using the aux mast.

This weekend I decided that in addition to the sanding and painting, I would look into making this mast tall enough to support a full sized full wavelength 80 meter delta loop.

Well, the best I could do was 57 feet. I really needed 65 feet but that additional 8 feet was going to kill this project for sure. Even 57 feet turned out to be spooky tall.

The original, drill stem, tiltover topped out at 34 feet. I added another 11 foot section of steel pipe to that a few years ago. This time I added another 12 feet of light weight aluminum tubing salvaged from an old beam.

I get dizzy when I climb up on the roof, but now I get dizzy just looking up at the new mast. Standing on the roof looking up at it is a real thrill. Reminds me of six flags.

It was hell getting it to clear the oak tree. I had a helper crank the winch to raise the mast while I was up on the roof pulling the mast horizontally against its hinge pin to angle it out from under the lower hanging branches.

I guess God heard my four letter prayer because the thing finally pulled free and started up. It looked like the top was bent a little but that just turned out to be a slight bow due to the weight of 140 feet of old coax that I was going to use in place of wire.

Turns out the coax was too heavy. It also turned out that the clever way I installed a pulley at the top to allow the wire/coax to run freely ended up tangling the wire. After fighting the tree for half an hour getting the mast raised, I was not about to let it down to free a tangle that might occur on raising it again.

It was only 57 feet up but even with glasses I could not see what the problem was up at the top where the wire refused to co-operate. I even took digital pictures at telephoto zoom and zoomed them some more on the computer. Sure enough, it was tangled, but not enough detail to suggest how to untangle it.

Luckily I had added a second pulley and halyard at the very top just below my failed cable installation. Reluctantly I let the 140 feet of cable run off the top pulley, deciding to use the halyard to raise a more conventional (and much lighter) section of wire.

As soon as the cable cleared the pulley, the mast snapped up straight. Even with only one guy pullin it back from the house. The project now looked to have some promise. Guess maybe I will have to find some other use for 140 feet of old coax.

Now I have to measure some antenna wire. I have been tempted to measure off ten foot sections of the garage floor to make wire measuring easier, just never did it. It always made more sense to measure the wire directly.

Well, I already know that I don’t have enough room to accomodate 270 feet of antenna in a delta triangle fashion, and I am going to use an antenna tuner anyway, so getting an accurate measurement is not critical. Besides, it will be fun to learn to use the dip meter again. Antenna tuner or not, I still would like to know where this thing is going to resonate.

I am pretty sure I can take care of at least 200 feet of wire in a triangular fasion. The other 70 feet will be made up of a wide spaced spread of two paralled runs of 35 foot of wire going to the top of the tower portion of my main tiltover.

I am doing pretty much the same thing with my horizontal loop now and it works just fine. I am hoping the new loop will work even better.

ZZ Wave Net antenna

November 13, 2009

I found this on the internet. ZZ Wave Net. This is a dual band loop antenna covering 80 and 40 meters.

I have been using a horizontal loop at 30 feet for over a year now and also have experience with a 40 meter delta loop. The 40 meter delta loop was an effective DX antenna but was taken down in favor of a bobtail. The bobtail is a two wire (vertical wires) bobtail so it is not as good as a real bobtail but it is better than the delta loop.

I am hoping that the ZZ will be better than the horizonatl loop. It will certainly solve some logistic problems. The horizontal loop gets in the way of the tiltover tower. So the loop has to be taken down for the tower to tilt over. If the ZZ can replace the horizontal loop it will solve the tower tilt over problem.

The ZZ takes a 65 foot tower. The best I can do is 57 feet. That is to the tippy top part of my auxilliary tilt over mast. The only thing this mast will be supporting is the ZZ loop. The last 12 feet of this tower is one inch aluminum tubing salvaged from an old beam that lost an argument with a tornado.

I figure I can make up for the lack of height by moving the end supports further appart. Got plenty of room to expand to the SE but not sure about the NW. If problems arrise we will linear load the thing until it fits the space allowed.

I probably should have added the following as a comment but here goes anyway.

I finally got the antenna up and running. It is running along with the horizontal loop. I left the horizontal loop up for comparison. Both antennas are tuned to the same part of the 75 meter band. One with a homebrew tuner, the other with an old KW transmatch. Antennas selectable through a large rotary switch. This setup provides instant comparison.

I have been playing around with these two loops on receive only so far. It appears that the new loop is about two S units better on receive on some stations with no effect on others.

I had originally intended to use some surplus RG-62 coax for wire. The coax turned out to be too heavy for the mast. The upper 12 feet of the mast is one inch aluminum tubing and was too weak to really support the weight of 140 feet of coax cable. It was replaced with normal stranded antenna wire which worked fine.

The lower part of the loop is supported by the 2.5 inch pipe section of the mast and coax worked out fine for that run.

Final dimensions were a height of 56 feet with the ends at 9 feet. I had to build a support out of cedar 4x4s to elevate the SE end to 9 feet. The antenna is just like the ZZ Wave Net but installed 9 feet lower than recommended.

This morning (Nov 29, 2009) I had my first schedule with my usual buddy on 75 meters. The new antenna is working fine. The old loop gets me an S7 or so but the new loop gets me 10db over nine.

He was amazed at the difference between the two antennas.

Just finished taking down the old horizontal loop. Don’t need an S7 signal when I can get 10over9 on the new loop.

Moxon or KT34XA

October 5, 2009

I have been thinking about turning my KT-34 into a three element moxon for 20 meters. Why? Because I think it would reduce the weight by a bunch and work better with my old AR-22 antenna rotator.

Yesterday I was reading up on moxon performance. The two element moxon was consistently 2 S units below a 160 meter loop at 50 feet. Granted, the loop has a capture area the size of Texas compared to the moxon, but this moxon performance is just a little better than what you can expect from a normal two element beam, about 5db.

I am already getting close to 8db from the KT-34 on all three bands. Why would I settle for about 7db on only one band. That is what I would end up with using a three element moxon on 20 meters.

No, it would make more sense to reinforce the mast so that it can take the additional load and just hope the rotator will slip its moorings when the strong winds arrive. It will screw up the feed line but at least save the rotator.

I am pretty much convinced that the winds that did in my HD-73 would also have taken out a prop pitch motor. So going lighter on the rotator should not make that much difference as long as it is not pinned to the shaft of the mast like the HD-73 was.

I am not about to spend 1000 bucks on a heavy duty rotator when I am pretty sure it would get shelled out too.

So the KT-34 is being rebuilt as is the mast. The antenna just needs the feedline attached and the capacitor insulators replaced. The mast needs to be taken down and the bent portion needs to be cut out. Then I need to come up with a clever way to mary the 2.5 inch pipe to the 3 inch pipe without welding. My guess is slip the smaller into the larger for a couple of feet and use two bolts spaced 90 degrees appart. Will also find a solid steel shaft to insert into the hollow of the 2 inch pipe at the junction. The lower 15 feet of the 2.5 inch pipe will be reinforced by welding some heavy streached chain to its backside. This may result in a future bend closer to the top. However, the 2.5 inch pipe is only 20 feet long. That puts the reinforcement just five feet from the top. I am hoping that will be enough to support the additional weight of the extra boom and two elements to convert the KT-34 to a KT-34XA custom.

Custom because the wide spaced additional three band director is going to be an old Mosely tri-band driven element sporting two traps. The extra ten meter director will be made from tubing scaps of which I have plenty.

I have already used the two Mosley traps and tubing to build a rotatable dipole using some scrap tubing. It worked very well on all three bands. All that needs to be done is telescope the tubing further together to make the element shorter and turn it into a director.

The only thing I am short on is boom material. I need to double the length of the existing boom. Increase it by 16 feet to a total of 32 feet. I only have about 13 feet available and it is not all 3 inch. Got three 19 inch sections of boom from an old single bander beam that was destroyed in a storm. Got another six foot section of 2.5 inch steel mast I would rather not use since it is heavy. Then there is a five foot section of scaffold tubing which is extremely light weight and hopefully extremely strong.

There is another 16 feet of mast now being used on the second tiltover but I believe that mast is steel (heavy) and about 1.5 inches in diameter. Probably not at all suitable.

I might be able to use three feet of the 1.5 to make up the difference in boom length for the KT but I am tempted just to let is go short. A three foot reduction in boom length can’t effect the gain that much.

The first task is to securely mount the gin pole mast by drilling holes for bolts in the top plate of the tower. Then removing the tiltover portion and loweing it to the patio. Secure both ends and the middle. Then cut the bent portion of the pipe out of the middle. Move the 3 inch pipe into the garage to weld on the uppper cable stays and paint it.

Next comes the 2.5 inch pipe. Move it off the roof and into the garage to install cable stays and reinforcing chain. Also need to figure out a good way to bolt the two pipes together. Paint the smaller pipe.

Move the finished pipes to the patio and position to bolt them together. Install the cables before raising to the hinge point. Once it is at the hinge point you wont be able to get to the cable stays.

The cables will be installed with a little more foresight. Will be using four cables. One RG6, two RG 213, one rotator cable, and one openwire 450 ohm line.

The 450 ohm line will be terminated to PVC insulators support off the tops of the cable stays. Rotor cable and both RG 213 runs will come down through the cable stays as will the RG6.

One RG-213 to the KT-XA. One RG-213 to the vertically polarized two meter beam. RG-6 to the TV antenna. Maybe use RG six for the two meter beam too? Then there will be the UHF TV antenna wich will use the 450 ohm open wire line for feedline.

It may not be entirely obvious but the two TV antennas need to be fixed mounted. That is, I know where the TV stations are and I need those antennas to point in that direction and stay there. Dont need the TV antennas rotating around with the ham antennas. The UHF TV antenna does not present much of a problem. Just mount it to the mast with two u-bolts. (might need to get new U-bolts to fit the larger mast.) The VHF/UHF combo TV antenna will probably need to be mounted to an extension arm off the side of the main mast. Ten feet below the large HF beam would be a good place. Need to determine the length of the extension arm

There will be a junction box at the top of the mast. Perhaps one at the hinge point as well. All cables will terminate in connectors at the juntion box at the top. This being done so that the antennas can be removed or serviced without worry about feedlines. Just disconnect at the junction box. The juntion box will be located high enough on the mast so that it is accessible from the roof of the garage as the mast it tilted down.

Getting the beam up onto the mast is going to be trick. The last time we did that, we used the step ladder straddling the garage roof peak to gain enough height to attach the boom to the mast. The beam was fully assembled as we installed it this way.

This time we will fully assemble the entire beam on the patio so we can test it. Then dissassemble and take the main boom section and short elements up to install the boom to the mast. This should be fairly easy because the balance point of the beam will have shifted to one end of the boom. My guess is that three elements will be up and one down as the boom is mounted to the mast.

Further assembly will be done at standing height from the roof by rotating the beam to position it then raising or lowering the mast by tilting it to bring the elements into play one by one.

Once all four original elements are installed we can to the XA modification. Add boom sections to the first ten meter director. Install ten meter director. Raise beam higher, install more boom lenghts, install the tri-band director.

Raise the antenna to full height and hope the swr is acceptable on all bands.

The official weight of the factory KT-34XA is 69 lbs. I am hoping my version will be under 60 lbs. Still, that is very heavy. Some of the weight of the previous installation will be offset by lowering the mounting point of the rotator. I am guessing I can set it lower by about ten feet. The only problem there is going to be attaching the saddle shaft to the antenna. Ten feet lower may put off the edge of the garage roof. My extension ladder is not long enough to reach that point. Will just have to play this by ear. I might only get a five foot lower mounting point. I definately do not want to have to install the rotator before I raise the pipe to hinge point. The whole purpose of the rotator mount is so that is can be accessed for replacement since it seems to be most likely part to fail.

Need to make some cable clamps and stays to support the new longer boom. There is a sturdy pipe extending ten feet up from the point where the beam is connected to the mast. The upper reaches of that pipe need a clamp with two ears to enable attaching the ends of two cable stays, one on each side. The cable stays will connect to boom clamps located a few feet in from the boom ends. The stays will be preadjusted to length to keep the boom level and prevent any sag or droop. I have a length of aluminum bar stock that is heavy enough for making clamps. I just hope there is enough to make three clamps. The mast clamp is no sweat but the boom clamps will need about six to eight inches of material per side times two. Need at least three feet of stock. Clamps will be bolted together and have extensions to permit attaching the stays. They should be a tight fit to the mast and boom so that they will not slip.

This is longer than I intended. Sort of thinking out loud and sort of off topic at the end. Then this is the ‘Off Topic’ blog. (more…)

Antenna Rotator Problems

September 28, 2009

The big beam has been freewheeling for nearly a month. I finally cranked the thing down and took a look. Feedling is broken and the rotator sounds like it has marbles rolling around inside it.

The rotator is an Alliance HD-73. I had always thought it was much better than the CDE AR-22 but upon investigation the HD-73 can only handle a wind load of 10sq feet. Most ham rotators do 15sq feet or more.

Before the misshap I had trouble keeping the beam aligned to the rotator box indicator. At one time that problem was due to a missaligned gear that was driving the pot in the rotator. The HD-73 uses a potentiomemter inside the rotator to vary the voltage to a meter inside the control box. Well, this time the pot was just fine. The missalignment was due to the pipe mast slipping in the rotator coupling. So, I drilled a hole through the clamp and into the pipe. I threaded the hole in the pipe and screwed in a big bolt. Sucker would not slip anymore.

The HD-73 does not provide any sort of breaking to the mast other than the inertia of the geared motor mechanism. After the mast was not allowed to slip anymore, the force of t he wind stripped out the gears in the rotator. So much for avoiding slippage. I guess maybe the KT-34 was a little too much, or maybe the rotor was a little too light. There was no downward force on the rotor. A side saddle mount to the mast included a thrust bearing that bore the weight of the antenna.

So now that mast is tilted over and the beam removed, I can concentrate on repair.

I have a 50 foot tilt over. The tilting over part is drill stem pipe. The pipe is hinged at the 20 foot mark to a plate that is supported on the top of two sections of rohn tower. Been using that since the early 70’s of the last century.

Once I had the mast tilted over I tied it down so that if we did have storms there would not be any more damage. We did have storms but the only damage was due to my forgetting the mast was tied down before trying to raise it. I wondered why it took such a strain. Before I figured out what was going on, I ended up with a bent mast.

Tried to bend it back. No way that was going to work without risking pulling the tower sections out of the ground. So now I am having to engineed a way to remove the mast entirely so that I can cut the bent section out of the drill stem and weld it all back together after reinforcing the pipe above the 25 foot level.

The first 25 feet of pipe is 3 inch. The rest is 2.5 inch. It was 2.5 inch that bent.

Took a look at repairing the rotator. Found a fellow who does that. He also sells rotators. Wants close to 500 bucks for a new HD-73. Wants 60 bucks plus parts and shipping to repair a wrecked HD-73. That is shipping both ways and I figure one way was going to be around 20 bucks. So we are looking at 60+20+20+60(?) or more. Possibly close to 200 or better for repair.

Panasonic has a brand new rotator with twice the wind load capacity of the HD-73 for 300 bucks.

Unfotunately in this part of the country a wind load capacity of even 20 sq feet is inconsequential. We get storms with straight-line winds approaching. 90mph. God help you if you get brushed by a tornado. So it really does not matter that I ended up with a used AR-22. It will work. There is not downward force since the thrust bearing takes up the strain. And now I no longer pin the mast to the rotator so slippage is possible. What I really need is a very good braking mechanism to hold the pipe mast from turning in the wind. Of couse I know if I had that, It would just shell out the rotator when I froget to release the brake.

I have two old AR-22s. The AR-22s use two rows of ball bearings to support the rotating part against the non rotating part. But there are only six bearings on the top and six on the bottom. Those six are held spaced evenly around the perimeter by a band with spacers to keep the marbles in place.

The HD-73 had a full course of ball bearings top and bottom. I salvaged the balls out of the HD-73 and installed them in to one of the AR-22 rotators. The AR-22 with the extra balls will go on my auxilliary mast which will serve to hold a two meter beam and a multiband High frequency HF Moxon.

The remaining AR-22 will be used in the side saddle mount on the main tilt-over. It is going to be a 20 meter Moxon.

Both AR-22 rotators and their control boxes needed work. Both these rotators are four wire with really cheap screw connections in the base of the rotators. To prevent the screws coming loose with use, I decided to remove the screws entirely and solder the roator wire connections into the holes left by the screws.

As predictable the AC capacitors in both control boxes had aged ungracefully and need replacement. The replacement calls for a 120 to 150 mfd 50 volt AC capacitor. I did not have one of those. I did have a couple of 120mfds at 50 volt DC which when hooked back to beack. Minus to minus with the plus leads going to the old capacitor connections after the old capacitor is removed. That worked.

Caution, don’t install larger caps or caps of much smaller value. That will not work. I initially installed two 560mfd caps figuring that if 120mfd is good, 560 would be more good. Trouble was it was no good. I finally got the thing to work well by connecting a 120mfd and a 200mfd back to back.

Another thing that allows better preformance is clean and well lubringcated gear mechanisms inside the rotator. After cleaning and lubricating, both rotators functioned much better.