So I have a Cushcraft A3S up at about 60′ and I’ve always thought it plays pretty well. Before the A3S I operated a Force 12 C3 on the same tower but from a different QTH. The problem I’m having is some friends of mine (“seasoned” Hams mind you) are always giving me crap about my “rotatable dipole” and “lame tribander” when compared to their 20 Meter 204BA Monoband antennas.

So I figured I’d do a little homework, ask a few questions from knowledgable Hams and then try to figure out just what the real differences are between my Tribander and their Monobander(s). Here’s a little bit of what I’ve found and also a couple observations…

One “S” unit equals 6 db of gain (http://www.ve3fyn.ca/nvis/Decibel.htm)

Doubling power equals 3db of gain (http://www.phys.unsw.edu.au/jw/dB.html)

The typical loss in a 100′ run of Belden 9913 (RG8) coax on 14 MHZ at 1,000 watts is .46 db (899 watts Effective Radiated Power) – (http://www.ocarc.ca/coax.htm)

The typical loss in a 100′ run of Belden 9258 (RG8X) coax on 14 MHZ at 1,000 watts is 1.087 db (779 watts Effective Radiated Power) – (http://www.ocarc.ca/coax.htm)

A Hy-Gain 4 Element MONOBAND Yagi model 204BA has 8.2 dbi (6.0dbd) of gain. (http://hy-gain.com/man/pdf/LJ-204BA.pdf)

And from the same manufacturer (with what I suspect are the same measuring techniques and formulas) the 3 Element TRIBAND Yagi (TH3MK4) has 8.0 dbi (5.8dbd) of gain. (http://hy-gain.com/man/pdf/TH-3MK4.pdf)

Very similar specs for the Cushcraft A3S vs. a Hy-gain TH3MK4 – (http://www.texastowers.com/cushcraft_a3s.htm)

Hmmmmm…

Maybe I should just switch my coax (from RG8X to 9913), pick up .63 db along the way and still have a solid db of gain more than a 20 meter 204BA Monobander fed with RG8X?

In the next few days/weeks I’ll gather information on a couple of other tribanders (namely the M2 KT34XA and Force 12 C3) and then I’ll compare those to their 204BA’s, but for now and until somebody can come along and prove me wrong, it seems to me that for a measly .2 db of gain and a little more directionality, I can’t justify erecting 3 towers, swinging 3 heavier, clumsier, larger and single band use antennas when you can have similar results on 3 bands and only one tower.

It’s a no-brainer in my opinion. Maybe someone can enlighten  me as to what I’m missing? Bring your best shot, but make sure you back it up with some kind of fact(s) or it’s just another worthless opinion.

73,

NØUN

It took a while but the time spent was well worth it.

The tower and antenna are up and working well. Thanks again to Keith KØKE who found the used A3S, lent a hand and his truck to pull it up.

A3S @ 60 ft. / 6,100 (and 60') Above Sea Level

The FT-990 is back and working perfectly thanks to John, KI4NR. He’s an absolute first class technician, his rate for repairs is more that fair, and he’s faster than fast! Playing with the FT-990, I actually like it better than my old Ft-1000D I sold off last time I got out of Amateur Radio.

As far as the amp, I blew a 125μF/450V capacitor in the Heathkit SB-200, but no issues. Went down to Fistell’s and picked up another one and guess what? Blew that one too. Didn’t even last 15 seconds. Nothing like capacitors going off like firecrackers on the kitchen table to wake you up and remind you that there’s some high voltage in that case! After talking with Keith (KØKE) who figured I had a couple other shorted capacitors putting the high voltage load across that specific one, it would probably be cheaper to replace all 6 caps and the entire board with a $80 PM-200 Replacement Power Supply Module kit from Harbaugh Electronics than to try and replace just the electrolytics. And so that’s what I did. Took all of a couple hours to assemble, wire and solder up the new circuit board and about another 30 minutes to install it. The Harbaugh PM-200 Replacement Power Supply Module kit comes with 6 new caps, all bleeder resistors, diodes and a circuit board. All the buyer has to do is follow the simple instructions; assemble and solder the board, then install it into the SB-200. Felt good to have a soldering iron and electronic “pieces parts” in my hands again, but I can’t ever remember having such a difficult time seeing the small parts though. Almost had to get a friggin’ magnifying glass… almost I said! Anyway, the amp is working perfectly now.

As far as the antenna situation… We’re moving forward, slowly. My friend Joe came over yesterday with a TIG machine and touched up about 20 welds on the aluminum tower and Keith (KØKE) found a used Cushcraft A3S for a couple hundred bucks, so it’s coming together nicely. I played hell trying to get the A3S resonant on the old element “tuning” markings, but once I measured everything and adjusted the elements per Cushcraft’s dimensions, she fell right in line. For some reason I can’t seem to get the SWR below 1.5:1, but I’m hoping it’s only because it’s 3 feet off the ground and still in “assembly” mode. Once it’s up at 60′ hopefully the SWR will drop flat to 1.1:1. Like I said,  hopefully.

Next project is to get it on the mast and erected. This should be fun…

NØUN Tower

73 for now,

NØUN