DIY Z Match

Happy new year with good propagation folks!

I would like to change my antenna for one fed with balanced feeder.
Therefore I would like to make a Z Match tuner as I have all the capacitors
and case.

My main area of interest being 80 and 40m.

Searching the web brings up various circuits, some with switched band for 160, incorporating a dummy load and straight through (bypass) and built in swr bridge. All I am looking is something simple that works well on 40 and 80m. Can any help please?

Hi Richard and a Happy New Year to you,


I had originally intended to run a ladder line antenna system with my setup but due to lack of sensibly priced tuners, (or even tuning capacitors for homebrew), I had to take a different path.

Any homebrew option is going to depend on what capacitors you have and maybe even the case to allow space for isolation. In Z-match tuners the capacitors run 'hot' so at minimum your hand capacitance will affect tuning and at worse you'll be literally buzzing with RF excitement!  
(Seriously, RF burns aren't funny.)

Most modern tuners use a toroid output as a 'kludge' fix for balanced output so might be worth looking at traditional circuitry or in other words old circuitry.

One I always fancied was the KW EZee Matcher and some details are in the following link :-

https://vk6ysf.com/kw_ezee_match.htm

Helpfully the circuitry and even coil details are recorded in this write up.


As I mentioned it will mainly depend on the tuning capacitors you have and whether you're intending to run QRP or QRO.

Might be worth looking around for older designs and an image search with Google for the more simpler circuits.


Anyway, hope that helps even if only a little and I'm sure there'll be some other suggestions.

(I went with a Pi-Match circuit due to single gang capacitors plus simplicity of construction but use coax fed dipoles.)


All the best,
Victor

Victor,

Always a wealth of information, that was exactly what I was looking for. I did actually make this many years ago to match a G5RV but when I stopped using the G5RV it moved on. Thank you for the info.

With regards to the capacitors, I have a couple of wide spaced ones I can cannibalise from my Pi match if I go that way. I am still deciding on antennas. For a couple of years I have used a Hustler 6BTV, but for my QTH, ground mounted with limited radials, it wasn't the best. I have a dog legged 80m dipole which works very well, but I would like 40m too. 

You mentioned RF burns, I have never experienced them. When first licenced, I was using a humongous Top Band AM transmitter and poking around I touched a capacitor (almost the size of a tin of beans) and did I feel it!

Once again thanks for your informative reply.

Take care.

Richard

Hi Richard,

No problem, just doing my best to help out my fellow radio enthusiasts.


Arrgghh! Been bitten by one or two caps in my time and you quickly learn to not touch such stuff! I've only had one major RF burn, (but many RF 'tingles' ), many decades ago but I'll never forget that one for as long as I live.


All your talk of balanced feed lines and matchers has got my brain going again and something I'd like to revisit as well.

If any further information may be of help you could do worse than perusing through old radio magazines at the following link :-

https://worldradiohistory.com/

I do remember an article by the venerable Rev. George Dobbs, G3RJV (SK) so just skimmed through and found it. On the above site go to the Practical Wireless link on the left and select the May 1998 edition. On page 55 there's a good article written by him with the basics of balanced feed lines and matching, might be worth a read. If anything it could lead you onto a better understanding/appreciation and maybe to a suitable project.
(Can't give a link unfortunately as the site is very dynamic but easy to navigate.)


Anyway, again given in the spirit of helping and ultimate radio enjoyment.


All the best to you,
Victor

Victor,

The link to world radio  history is really good. I didn't know it existed.

Thanks again,

Richard

Just an update.
I had been using an 80m dipole coax fed. Now have the Z Match, coax changed to twin feeder from spectrum (95 ohms)
15 feet removed from each arm of dipole and the resultant doublet works on all bands 80m upwards. This twin feed is so quiet and really I'm impressed Spent an hour or so on WSPR 30m and quite pleased with the results.