So after a long time of sitting in my cabinet, I have found some time to build my DC7GB 2m Mag Loop kit and here is the associated Funk Article PDF and I was wondering if anyone else has built one and has any operating experience with it. I have only operated HF mag loops in the past.
Google Translate and my wife’s broken German skills leave a bit to be desired and I wanted to confirm exactly where to connect the coax in the project box and I would like to know why the coax length in the box appears to be critical. I would also like to hear about how people mount this thing in the field…
Hi Tom,
I presume this is the loop that is a track on a PC Board? I reported on that here on the reflector towards the start of the year. I had intended taking it as my “gain antenna” for my HT on my trip to Dayton this year - that got cancelled of course. I have used it with a couple of the local repeaters here and it worked as expected.
To trim it onto the exact frequency I used my $50 NANAVNA and my RigExpert Analyser doesn’t cover 2m (I have the just HF one).
It seems only like I made a short comment about it here:
I just dug out the box with the loop antenna in, to see if I have any documentation in English for you - sorry - it’s just a printed article in German!
It’s very straight forward to build though - your main issue will be how to mount it to be solid and not be affected by anything or anybody getting too close to it.
As far as I can tell the instructions call for 100mm of RG-178a/u. Why does the antenna need that 100 mm? There is a very short distance between the BNC and the driven loop and they route the coax so awkwardly from what is show in the picture. Also they don’t show the actual connection of the coax to the PCB in the pictures—is there some obvious reason why they need that big length? Is there a reason not to run 1/4 of that length to go straight from the BNC to the driven loop?
Board 43.30 inches x 35.40 inches with “etched” antenna,…
That would be 1m alongside … seems a bit big for my HT
I guess they mean 4.4 inch etc…
It’s all better in metric: Lieferumfang: Platine 110 mm x 90 mm mit “geätzter” Antenne,
Luc ON7DQ
Antenna ready for operation on top of my RD-5R DMR HT from Radioddity/Baofeng.
Distance from central coax connection point to end of connector at radio with adapter 100 mm (10cm). Why this length - I don’t know but it seems a reasonable distance so that the metal in the HT doesn’t affect the loop perhaps?
73 Ed.
PS I use the HT with a speaker-Mic so I am far enough away from the antenna.
Maybe I don’t get it but why would anyone would like to take such an unpractical and fragile thingy on a summit?
A telescope antenna or better a J-pole on some glassfibre-telescope pole just make so much more sense (and probably a way better take-off).
The loop is very directional so for summits with communications infrastructure that make interference across 2m, a directional antenna such as this loop should help. I haven’t used this one on a summit yet (it was planned for use on two summits in Ohio in my absolutely minimum packsize needs on the trip to Dayton). It’s small size means it’s easy to protect using a plastic sandwich box or similar.
Now if you can carry it a J-Beam 8 element 2m Yagi, aluminium mast, guy ropes and pegs would technically be a better option but for a small antenna, this loop beats the rubber-ducky.
As does a J-Pole (normally as you say plus FG mast) and the RH-770 telescopic is also better than the standard rubber duck antenna.
It depends how much you want to carry - if you want something really small and light, then this is worth a try from what I have seen, just using it from the home garden. And at €12 it wont break the bank!
I don’t think the 100mm is the length needed for distance to the radio. In the article they don’t even have room for the coax it seems and it has to be looped in the box:
