For portable operations, it’s great to have an antenna that is pretty efficient; small and light to carry; and fast to deploy and take down.
For me, that’s an EFRW of between 21+m and 6.5m, with a small L-match. Recently I came across a neat design by Denis K0TX (digirig). It’s a small spool (diameter 8cm), with the option of putting a transformer into the spool. He sells it as a 10m long EFHW.
I put together two of these. One is simply a 21+m wire for hooking up directly to the L-match; the other has a 9:1 transformer, and uses 5m RG316 as CP. Fits on the small spool if you use 28 wire. Both are quick to deploy and, more important perhaps, very quick to roll in. An benefit of this design is that you can adjust the length continuously, down to using it as a 6.5m vertical on a pole, by blocking the spool putting a hook through the holes (works well down to 30m with the L-match). 100g all in.
Very neat indeed. I’m always tempted to make a long wire with a 9:1 transformer for SOTA, but I can’t decide whether it’s a good idea or not.
Needing a tuner is a bit annoying for me. I have a ZM-2 ATU in a drawer, but I find it a bit bulky and heavy. On the other hand, being able to change bands from the “chair” without messing around with the antenna and links is quite appealing.
Maybe you have a plan for a mini L-match to make it work on 40-30-20-17-15?
I have built a few l-matches. This one here just about matches anything:
For normal use a simple version is sufficient with 4 inductors. It matches my EFRW from 60 to 15, in line with the requirements of my QMX mid-band.
With the QMX I don’t see the benefit of an automatic tuner like an ATU-10. Bigger, heavier, needs power. And it’s not faster, as you need to go into the QMX tune menu anyway. Pressing a button or turning the cap is about the same time.
My small 80g l-match has a resistive bridge built-in. So I can tune directly with key-down without going into the tune menu of the QMX. Which makes it faster than an automatic tuner. (You can leave the choke out, it doesn’t make a difference I discovered). I built this to hook up directly to the QMX, reducing connectors and having a clean set-up. With a 3S Lipo 650mAh taped to the QMX it’s a very compact unit.
