Rybakov HF verticals

These are end-fed antennas for HF usually. Commercial versions are available. 

Some years ago I bought one from SRC in Wales. Although I believe this is no longer available, they all have one thing in common: the end of the antenna is a high impedance, so a transformer is needed to get the SWR into the range of auto ATUs found on modern rigs. Usually this is an UNUN built into the antenna.

In getting things together for my free PDF book, I realised this was absent from my website! This is now corrected. As mine had been unused in the back of the garage, I swapped mine for an active RX antenna that works well. The swap was with Jason M0NYW. 

See https://sites.google.com/view/g3xbm4/home/antennas/x80_1 .

x80 Rybakov vertical

I bought this about 10 years ago, but apart from a few weeks it was not used and is in perfect condition. 

For those unfamiliar with Rybakovs, these are multi-band antennas that are end fed via a balun. In most cases the auto-ATU in modern rigs can easily match the antenna on most bands. In many cases the SWR is low even without an ATU. They make useful multiband antennas. I believe there are more recent versions available. 

On HF I am almost exclusively on 10m, so this was wasted, so I have recently swapped it for an active RX loop.

See https://sites.google.com/view/g3xbm4/home/antennas/x80 .

A Rybakov antenna on the bench?

In the garage I have a virtually unused SRC X80 end-fed vertical antenna. This was very briefly erected in about 2011 and has remained unused for years. I took it down as reports said it blew around in high winds and at the time my interest was mainly on 10m for which I had a suitable antenna at that time.

The X80 is a sort of Rybakov antenna. These are end fed antennas fed via a unun transformer so the very high end impedance is transformed into a VSWR less than 3:1 that can usually be matched via the auto-ATUs in most modern HF rigs.

As an experiment, I tried loading up the coax to my 2m big-wheel via this Rybakov transformer. I can get quite a good match on a couple of HF bands (at least) but on some bands the VWSR was so bad that the rig just turned off!

By ear, I think my small indoor magnetic loop is as good!

HF antennas

Some years ago I bought an x80 vertical antenna. These are basically Rybakov vertical antennas. I erected mine briefly at the old QTH, but have not done so here. I would need help with erection, whereas my end-fed I managed to string to a nearby tree on my own. The end-fed is a good match on 10m (my favourite HF band) , where it seems to do quite reasonably on FT8.  So, for now, the x80 is unused.

At the time (2011) the x80 had mixed reviews. Some said the aluminium flexed too much and broke. Being a vertical, it is probably noisier than a horizontal antenna. If you have an auto ATU it is quite an easy way to get on several HF bands. These days I think there are stronger versions around.

See https://sites.google.com/site/g3xbmqrp3/antennas/x80

Rybakov antennas

The basic idea of Rybakov antennas is to feed these at the high impedance end via a transformer so the impedance is brought down to the range (usually VSWR better than 3:1) that can be matched with the auto ATUs in many modern HF rigs.

Somewhere in the garage I have an x80 antenna which was a commercial version. I think this antenna is no longer available, but I guess similar antennas are available. The one I have was criticised for blowing wildly in winds. If I can erect it on our bungalow, it should give me access to several bands.

If you buy the toroid formers and wind the transformers, Rybakovs are quite easy to make. There are several examples on YouTube and elsewhere on the internet.

x80 antenna

A few days ago I mentioned that my HF antenna (a Par end-fed) had blown down. Sadly these days I need help with antennas as my ladder skills (even on to a flat garage roof) are probably beyond me safely.

In the garage I have an almost mint x80 antenna fed with a 9:1 un-un. Reports of these vary with some saying they can break in winds. For now, when I have got a suitable support, I shall probably erect one as it should give reasonable performance on the higher HF bands. At the old QTH, albeit higher, it worked quite well.

See https://sites.google.com/site/g3xbmqrp3/antennas/x80

Antenna choices

In the very near future, I have to get a tree surgeon in to trim my silver birch tree. This is the support for the end of my 35W Par antenna for 10m, 20m and 40m. One possibility is the erection of my x80 vertical. This is in nearly new condition and has a 9:1 unun in the base to bring the SWR down to the sort of SWR that can be matched with most auto-ATUs. The drawback is it is quite "whippy" and blows around in the wind. It has never been used at this QTH.

See https://sites.google.com/site/g3xbmqrp3/antennas/x80

WSPR with the X80 and 5W

Well, here is a summary of my (intermittent) QRP WSPR beaconing tests since I erected my X80 vertical at lunchtime today:

• Bands tried 80, 40, 30, 20, 17 and 10m (reports received on all bands tried)
• Reports from 25 different stations in 14 countries and 3 continents
• Best DX 6105km on 17m

So, a reasonable test for the antenna and I believe it is working out pretty well so far.

Useful multi-band HF vertical

The Snowdonia Radio Company is offering the SRC X80, a 5.8m long multi-band HF vertical matched via a 9:1 unun matching box. This sells for just £47, which is excellent value compared with similar offerings from the Japanese manufacturers. Such Rybakov antennas offer a decent match, easily brought to 1:1 VSWR using an auto ATU, on the higher HF bands. On the higher bands performance is quite acceptable considering the compromise in size. In the latest edition of PW Magazine G6MXL reports working plenty of DX with 50-100W using one.