This past weekend, my good friend Vlado (N3CZ) and his wife came over to the QTH for the afternoon. It’s been a while since our families got together, so it was fantastic to hang with them.
I’ve been trying to tempt Vlado to do more field activations–we’ve done a number together in the past and it has always been loads of fun. Thing is, both of us have pretty active family/work lives, so it’s challenging to make schedules work out.
Nonetheless, our 2022 goal is to do at least one activation per month as a team!
MK-911
If you recall, a couple months ago, I posted an activation report and video using my buddy Eric’s 40-10 meter doublet. I called it a “stolen” antenna because it had been on loan to me for so long, I think Eric forgot it even existed.
Eric’s doublet was build around a Hughes Aircraft MK-911 Dipole Fixture that was designed and manufactured for the US Military and appears to have been part of the PRC-74 manpack radio-set.
I had assumed Eric found this as a one-off at a military surplus sale. Turns out Eric (and a few readers) made me aware that it was available at Fair Radio Sales in Ohio for $10.
In fact, here’s a link to the MK-911.
I decided to buy two of them: one for me, and one for Vlado. The temptation was strong to purchase a few more just for the 30 feet of 72-ohm military-surplus twinlead, however I understand that there’s a limited inventory and wanted others to be able to purchase this gem.
I was also thinking this antenna fixture would pair beautifully with Vlado’s Yugoslavian RUP-15/PD-8 manpack or even his IC-703 Plus.
Doublet time!
While our wives were catching up, Vlado and I made our way to the storage shed and opened my antenna parts boxes.
I did a little digging and found what I was looking for: some wire I purchased at a thrift store many years ago.
This wire has a black jacket that’s quite slick. Guessing it might be 20 gauge and might even be teflon coated. It was ideal for antennas and eyeing it, I thought there might be enough for two doublets.
For a Norcal-inspired doublet–which covers 40-10–we would need two 22′ legs. I decided (prior to cutting) that I wanted our doublets to go as low as 60 meters (5,332 kHz) and cover everything above. 60 meters is such a useful band. Thing is, I hadn’t done research into suggested leg lengths in advance.
We decided to pick a longer non-resonant length and just give it a go. If it worked, great–if not, we’d cut them down to 22 feet and be happy with 40M and up.
We cut the legs to 31 feet, so there’d be a total of 62 feet of wire in each doublet. Many thanks to my daughter Geneva (K4TLI) for helping stretch, measure, and cut the antenna wire with us!
Assembling the antennas was incredibly simple as there are built-in binding posts attached to the twin lead on the winding fixture.
Vlado and I both decided to use the winder as the center-insulator of the antenna. This is actually how this military fixture was designed to be used. The negative, of course, is that the center insulator is relatively heavy. This isn’t a problem for me at all since I use super strong arborists throw lines to deploy my antennas.
Eric (WD8RIF), by the way, actually detached the twin lead from the fixture and posts on his unit and built a new center-insulator from a discarded 35mm film canister (see photo above). He wanted to keep the weight down so he could support the center of the doublet on his fiberglass masts.
Testing QRV!
I had planned to hook up the doublets to my RigExpert antenna analyzer, then I realized it was essentially an unnecessary step.
The big question for me was, “Will my Elecraft KX2 find impedance matches on 60M and above?”
Vlado and I connected the doublet to the KX2 and tuned to 5,332 kHz. After confirming the frequency was clear, I pressed the ATU button. The KX2’s internal ATU churned for a couple of seconds and confirmed a 1.4:1 match.
Score!
We checked all of the bands above 60M and the matches were even better.
Standing in the middle of my driveway, I asked Vlado to load the POTA.app website and look for CW spots.
We then proceeded to work about three stations on the air in CW with 5 watts. All of them gave us 599 reports!
It was serious fun.
As I mentioned to Vlado, it might have been the first time I’ve ever used an HF “Handy Talky” with a doublet antenna!
In the end, we both walked away with two effective military-grade field doublets. A perfect antenna for our monthly “Team Baklava” activations.
2022 Activation Challenge
Last year, my personal challenge was to validate all of my park and summit activations with 5 watts or less.
Since I’m very much a QRPer and primarily a CW op these days, this turned out to be low-hanging fruit; lower than I would have guessed in this part of the solar cycle.
For 2022, I plan to continue the 2021 five watt challenge and add another layer…
This year, my challenge will be to build a new antenna each month and deploy it at least once during that month during a field activation.
The MK-911 doublet will count as January’s antenna.
I’m going to allow myself to build these antennas from anything and everything. I might even cannibalize a few of my broken/worn-out antennas.
I do want to keep these projects quite simple and easy for anyone to build in one sitting. I’ve gotten so much positive feedback from the super-simple speaker wire antenna I built in the field last year no doubt because it was so easy to build and super cheap.
I already have enough ideas to take me through the summer months, but I plan on dusting off some of my antenna books for more ideas!
With that in mind, I welcome your input! If you have a suggestion, feel free to comment!