Other SOTA sites: SOTAwatch | SOTA Home | Database | Summits | Video | Photos | Shop | Mapping | FAQs | Facebook | Contact SOTA

1 : 49 Balun in an old plastic film can

There’s always plenty of time at Christmas. Especially when the weather is not so great -

The other day I found out that a 114 - 43 fits wonderfully into an old plastic film can for photos when it is wrapped.

Now I have finally put the idea into practice and built myself a universal 1:49 balun. Depending on the wire length, I can then be active on different frequencies. I can pull up the different lengths of wire on the mast and simply change them at qsy. This way I have a suitable EFHW for many bands.

I chose a slightly thicker wire (approx. 18 AWG) so that I can also use my small 50 W PA.

73 Armin


I was going to suggest you could call it the “Kodak” but I discovered there actually is someone with the callsign K0DAK. :slight_smile:

What about the “Agfa”?


1 Like

Amateur Great F? dont know Antenna

1 Like

It is simply a SCB = slide can balun


73 Armin


I know one word for F and it is not Forum and it is not for forum :innocent:

Excellent! I am partial to dental floss cases, hi hi - fred kt5x /ws0ta


With the same inspiration, I made this 9:1 unun back in 2017 with a water turtles food pot.

Merry Xmas.



…that also looks like it fits perfectly in terms of diameter for the wound toroid. Of course, everything a little bigger - for more power.

I think you can get two 114 toroid on top of each other in the film can. With 18 AWG wire it should then also be enough for 100 watts.

73 Armin

1 Like

This film cans are also good for current baluns (aka CMC).
A CMC in such a can (yellow arrow) and one without a can (red arrow).

73, Ludwig


Hallo Ludwig

I believe that you can get a 2nd 114 toroid in the can with it… in addition to the 1:49 balun.
And then you could even add a current balun in the version of DG0SA.

If there is room for a balun to W1JR ? ? That will be too narrow even with RG 174.
I have my current balun after 2m coax cable in the direction of TRX.

73 Armin


Hello Armin,

Then the 2 m Coax, especially the outer conductor, acts as a part of the antenna. One of my setups with CMC is descried here.

If you compare the right CMC (in the picture) wit the film can you see, there is not much room left. The female BNC connector is long inside the can. It’s one to mount on a coax cable. I like it because of the reliability. The toroid is long to increase the conductivity. The number of windings is limited by the inner diameter of the toroid. Using the mentioned DG0SA system would not allow noticeable more windings to compensate the lower productivity by a shorter toroid to get more room for a second core.

73, Ludwig

1 Like

HAllo Ludwig

I have several RG 174 cables of different lengths with 2x BNC in which a 140 - 43 is wrapped. Depending on the antennas I play with the position of the toroid. In addition, with the cable often gives the possibility to take a more comfortable place.

You are right, of course. For the EFHW, the coaxial cable is part of the antenna in this system.Therefore the toroid in my approx. 2.50 m short cable is also on the device side in this use.

In 95% of all my activities I am using a vertical radiator and single radial. Then the balun is at the antenna base. (I just turn the cable around)

(If you want to have the 0.05 lambda part of the 1:49 balun separately and not via the coaxial cable, you have to lead it out before the current balun. That would be then mechanically somewhat more complicated).

By the way, I have not installed a BNC connector, but the RG 174 is connected directly to the balun and a short piece is led out. If the connection is made in the hole of the toroid, you can save some space. I fixed the RG 174 from the inside and outside with cable ties. If necessary, I cut the outer cable tie and slide the cable into the box to expose everything.

Of course there would be applications where a voltage balun and a current balun connected in series would make sense… (Somehow I am not a friend of dipoles or loops in SOTA activations). If you put 2 small screws or sockets through the cover to connect the antenna wires, you could do something like this with 2 pieces of 114(-43) toroid in the photocan without any problems.

73 Armin


great disscusion guys… I have learnt a lot, thanks all.

Geoff vk3sq

1 Like