Rigs, Antennas, Tuning, etc

Looking at a new base station rig, and since I am notoriously cheap “frugal”, I decided to get another TYT TH-9800 rather than a full-fledged, true base station. I have one of these in my truck but really getting to know the unit is difficult in the field. I figured having a ‘base’ station allows me to really learn the technical depths of the radio and gets me in on the cheap.

Spec-wise these radios get great reviews however the biggest complaint is that these things eventually ‘die’. From what I can gather, it’s likely due to people over-keying at max-output and frying the output amp; the electronics are not as robust as the Yaesu counterpart this unit was derived from (but I mean, it’s also a fraction of the price, sooo). It appears these things are great as long as you remember their upper limits.

While I was planning out this purchase, I suddenly realized I need to figure out an antenna – obviously, a mobile stick won’t suffice for a base station. Whatever it is, it needs to be discrete – enough to get to the local repeater. Anything beyond is gravy!

After lots and lots and lots of reading, I finally settled on a Slim Jim design out of the UK that uses a fancy-dancy calculator provided by M0UKD. ‘Local’ suppliers of ladder line appear to sell this in rolls of 100′ plus shipping – I needed like 6′, so VA3DAE generously stepped up and donated some 450Ω line he had laying around.

During all this reading, I got thinking, how do I ‘tune‘ the antenna? I have some old SWR meters I need to confirm will work. But can I buy something (cheap) or even better, build something using stuff I already have lying around?

Enter Arduino. Except for most projects I found are for HF, not where my interests lay being VHF+UHF.

Apparently, you can do VHF+UHF by swapping the DSS frequency generator out. Problem is, 1-30hz generators are cheap and plentiful. Above 30hz appears to be near impossible to find.

I’m sure by the time I’m done I’ll have invested enough quid to have covered the costs of a pre-fabbed unit built by Ed’s Antennnas out of Sunnyvale CA. We shall see. Either way, next time I have to travel to the valley I may stop by Ed’s.

Random: Coax Line Reference chart: http://www.miklor.com/COM/UV_CableLoss.php

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