Some of you in passing my place near Singing Hills on Road #1 may have noticed things going on in the back ‘40’. Well, things were going on. Last year during the ARRL 10M Contest I lost my rotator on the 125’ tower. I had swung southeast to see if anything was coming in from the Bahaman’s. Oscar – CO2OJ in Havana had e-mailed me and indicated he’d be on over that weekend. I didn’t find a whole heck of a lot in that direction and when I went to swing the (then) KT34XA back to the East – nothing happened! Hmmm, no directional antenna for 10M – what to do? I have a New Wave Antenna 26’ Portable on which I could erect my bamboo spreader, two element, 10M Quad but that would take up time. I could erect a 10M vertical but that could turn out to be an exercise in futility. So, I limped through the rest of the contest with my 80M dipole loaded on 10M. I didn’t accomplish what I’d set out to do that weekend (WAS on 10M, again) but it was a fun exercise. The crux of the problem was ‘I needed a new rotator!’
For some time my KT34XA had been suffering from the typical KT34XA problem on 15M – its most resonate point was 20 MHz. M Squared (M^2) in Fresno offered a kit to upgrade the KT34XA to a KT36XA which they claimed would do wonderful things for this triband, beam. I expended the $300 for the kit and really was impressed with the hardware they offered in this kit. Very nicely machined shorting bars to take the place of the flimsy aluminum straps with which the beam original had come. The hardware was stainless steel with the nuts being what are called ‘aircraft nuts’ or nuts that are manufactured with a nylon insert which acts like a lock washer.
It must have been around June that I’d contacted Colorado Tower Work for a quote. Jack and I haggle quite a bit but we did come to a meeting of the minds. He has a crane service “Rocky Mountain Boom” out of Longmont with which he works closely. And, I needed a crane that could boom up to about 150’ to do the job or removing the KT34XA from the 125’ tower.
It took a bit of precision work on the part of the crane operator to remove the KT34XA and not bump the 2 element, 40M beam (402CD). It finally reached the ground and I started my modification which took about 2 weeks and then to get it back up the tower we had to play the, “wait on the WX game.” Crossing my back ‘40’ with a 50,000 lb. crane could allow it to become a permanent fixture if it were to sink in the damp soil of my bog.
The modification was a real chore. Not only did the shorting bars have to be changed out but the capacitor tubes had to be changed out also which were not an inclusion to the kit. M^2 wanted about $8 each for the tubes of which there were 16 required, plus shipping from CA. I went to Home Depot and acquired the same diameter and wall thickness tubing at $1 a foot which I cut to the proper lengths on my band saw.
Once the modification was complete I attempted to check resonance points with the beam about 6’ off the ground and saw that, at least, there was some resonance’s where I wanted them – especially on 15M. Finally we got a break in the WX and the tower climber was summoned plus the crane. It all went together like clock work and the initial checks with the beam back in place didn’t produce the curves that I would have like to have seen using the MFJ Antenna Analyzer. Finally I connected the antenna to my HP Automatic Network Analyzer and found on all three bands the Return Loss to be acceptable across all three bands. On 15M the R/L was on the order of 12dB but attributed that to an interaction with the 40M beam that resides above the tribander.
“On the air” testing indicated a definite improvement over the old KT34XA. The front to back ratio seem to be better and I am able to receive a response from DX stations, in a pile up, with only one call from me – and running only 100 watts. When running the Alpha amplifier I’m able to talk to whom I want when I want, anywhere in the world.
In Summary, let me say that my objectives have been met: new rotator installed, new rotator control cable installed, new transmission line (7/8″ Helix) installed, KT34XA modified and upgraded to a KT36XA and installed. Monetarily, my wallet was lightened by about $3,500. This is not an inexpensive hobby by any stretch of the imagination. To break that down; the mod kit was $300, two times crane service was 2 X $400 = $800, labor by Colorado Tower Work was $1600, new rotator was $600, rotator control cable was $300, a couple of hundred in miscellaneous parts and pieces, if I’d have had to pay list price for the transmission line it would have run $1500 (it was obtained in a trade).
I knew going into this project that it was going to run close to 4 grand but, having a $15,000 installation of a 125’ tower, one antenna on it not working very well and neither of the beams on the tower Rota table
Dave W6OAL –
Olde Antenna Laboratory 41541 Dublin Drive Parker, CO 80138