I think SMA connectors are not a good choice in a situation where the thing being “plugged” in can exert significant bending moment on the device (the HT) and probably its PCB if the whole thing (radio plus antenna) falls over.
Then they use the plug on the radio and the socket on the antenna, that’s backward thinking.
The APRS tracker I have is configured the same (wrong) way. The plug in the radio should have a rotating body section to allow it to reach the correct torque as per the SMA specs. Hand tight is not tight enough. But instead there is a flange on the antenna which screws down onto the plastic (flexible) case. Very poor design.
Yes, probably more accurate to put it that way, but not having any modern Moto HT’s (only have the GP328/329/339 HT’s) I wasn’t aware what they are using with more modern ones. Still, not something I agree with (very backwards approach as Andrew mentioned) and highly annoying given it means unless you have only one type that you need to have two antennas with the male and female connectors or at the least, suitable adapters
Totally agree - although I suspect they went to SMA to enable smaller form factor. But, have also had BNC connectors fail on several radios as well, nut yes the BNC does seem to be a more physically robust connector in terms of bending moments.
I read that SMA connectors have a designed life cycle of 100 connections! Not ideal for SOTA operators who could be fumbling around in harsh conditions, snow etc while wearing gloves.
You’ll have seen in the video that I do try to minimise the strain on the connector by taking a loop of coax around the belt clip. Also, I use an rh-770 antenna and Spectrum slim G as my summit antennas. Both have BNC connectors. This way I can leave the SMA to BNC adaptor on the radio and quickly change antenna using the BNC. MY Sotabeams filter also has a BNC adaptor attached for this purpose.
Really only if you want the performance (insertion loss, reflection, power handling etc.) to remain in spec at 18GHz. At DC like 2m and 70cms it’s not a big issue.
The big downside of SMA rubber duck antennas themselves is that on a real SMA connector the male pin does not rotate in the female socket, you insert the connector and rotate the locking nut to hold it together. SMA rubber ducks have the male pin rotating in female socket and thus does cause much more wear.
Good precautions to minimise the number of SMA disconnects.
We can’t do anything about the radios using SMA connectors, and an increasing number of new models use them, so they are unavoidable. Your approach is a good one, I do similar things with my Yaesu HTs as my external antennas all have BNC plugs on them.
I’ve heard the same, but I also have a 17yo Yaesu VX7r, purchased new by me when I first got licensed, that is still going strong. I did more or less permanently mount a BNC adapter to it in late 2020 (have standardized on BNC for all field radios and antennas), but prior to that I was always swapping antennas to “fit the mission”.
Hiya Fraser, i watched this video with great interest, I use an FT4XE and it performs brilliantly on summits connected to the Slim G, but I find it susceptible to pager and other RF breakthrough, the SOTA beams filter really is a fantastic little bit of kit kills all the breakthrough and other guff, and makes activations very easy! I recommend them to anyone using a handie talkie for activations they can really make the difference between a contact, and no contact on 2M FM!
The SMA
417 activations down the log I am still using the same IC 92D with its SMA socket. This plug intrigued me. Designed for the giggly Herz bands, as Andy says “it plays with HF and VHF spectrum”. it is made from SS and gold flashed with PTFE insulation. It is well designed and robust. It flashes over at 400V. The mechanical connection to the coax is sound and fairly water proof, but some heat shrink cable strain relief is useful. It does not suffer the mechanical design limitations of the BNC and is very light compared with the N type. I run 100W SSB HF and 50W VHF without releasing the smoke.
The purists will say that the plug should only be mated once and then torqued up but for me the SMA has been a light, reliable connector for many activations. I am also able to connect the same piece of coax to my HF balun or end-fed 2m halfwave to my FT857 (with convertors) and IC92D. I do carry a short spanner, just in case. It was made for me from titanium by my son.
If it were possible I would however standardise on the screwed BNC (TNC) this is easier to use than the SMA and is both mechanically and electrically excellent. Alas I doubt our little handhelds will not go that way any time soon.
Hi Viki
I’m planning to do some summits in Sutherland in the second half of May so will keep an eye out for alerts from Aberlour to see if 2m will make it that far. I’m using an FT818 so will have HF as well.
Andy
MM7MOX
