9:1 Beverage transformer

Dolly Parton may be working nine to five, I work from nine down to almost one.

It’s time to give the short beverage another try. Two years ago I put up a copper wire along the fence. Lucky for a change: the fence runs from SE to NW. So the beverage antenna is pointing straight to the USA and upper Caribbean. I used that as an unterminated beverage antenna with an improvised 9:1 transformer. The wire comes from a broken current transformer that I partially unwound. Total length is about ninety meter. Too short for a textbook beverage but anything could be better than nothing.

Last year I didn’t use this RX antenna. I used the commercial active RX loop instead. This past summer I had success with my mono-directional terminated single K9AY style loop. I cannot put up a real K9AY RX array since it’s position would be far from optimal with respect to various obstacles and (not) being in the clear. I need to stay in a 2D plane. So two separate loops could be an option: one for USA and another for the Far East. Or point the loop to the north-east and put the USA beverage back into service. But then I need another 9:1 transformer.

More than four years ago I ordered a batch of parts for a project I haven’t even started. But I ordered a bunch of binocular cores along. We call ‘m pigs snout or pig’s nose core in Dutch. I wound a classic 9 turns – 3 turns transformer to obtain the 9:1 ratio. Actually it may have been ten turns on the hi-Z side. Winding toroids… I have a love-hate relationship with small coils since I was studying RF electronics and doing measurements on self-made Hartley oscillators. Don’t ask.

Finally time to install the software that came with the AA-54 analyzer. I like this device but I have yet to learn how to use all it’s possibilities. I have never used the software before and skipped the RTFM part.

Below is the SWR graph when loaded with a 470 ohm carbon resistor. Looks OK to me. I didn’t cut the resistor’s leads and this isn’t really a low inductance resistor type so it might actually be better. But for a simple RX antenna transformer, it should do just fine. Assuming the beverage impedance is in the 470 ohm range. I actually should measure first then wind accordingly but this transformer might end up in a K9AY loop anyway.

First I will put up the loop and the beverage at the same time towards the USA and do a real time A/B comparison. If the beverage does as well, it’s a keeper. Because it doesn’t consume any real estate. I don’t dare to hope it will outperform the loop. In that case, I simply will have to put up another improvised beverage to Japan. It never ends, it never ends…

Actually, I have used the beverage in the CQ WW CW SB80 category. I didn’t do an A/B test (yet) because many things interfered with my free time before the contest. And I relocated the loop when setting up for this contest.

I’m under the impression that the loop performs better than the beverage. I have no data and numbers to prove this. It’s a feeling. The beverage wire is not in the clear but above plasticized fence wire or rusted barb wire. It seems that it offers less signal and more noise. Maybe it would help to terminate it, but then it would favor the long path because the coax is attached on the western end of the wire.

I always get a kick when theory matches experimental evidence. There certainly is noticeable directivity between the beverage running East-West (USA) and the loop that’s NE-SW (JA/ZL). DL is at 83° from here. When going from the loop to the beverage, the German signals becomes stronger but the noise too.

In the contest I noticed that signals from Africa (z33 and deeper) were strong. Later I discovered that I had the loop reversed with respect to the terminating resistor. So in fact it was favoring Africa and not Japan. My bad. I fixed that after the contest.

I’m typing this ten days after the contest. In the mean time I have made about hundred fifty contacts on 30m (10.1 MHz). In a few cases the loop was the difference between making and not making a QSO. On moderate signals from moderate DX, there is a difference between the loop and the short beverage. Both are perpendicular to each other. Still the beverage is noisier than the loop. So sometimes even if it’s not in the right direction, the loop offers better S/N.

I also did some Top Band SWLing last weekend in the ARRL 160m contest. I actually could hear a handful of Americans on the beverage and the loop. No comparison with the TX antenna since it’s currently not up. I am making another 9:1 transformer and have put up another loop wire. So the plan is to do a decisive A/B real time comparison soon in order to determine if a loop is better than the short beverage if both are ‘pointing’ to the same direction. I’m discovering unexplored  territory here.

2 replies on “9:1 Beverage transformer”

Hi Brian. Thanks for your note.
I absolutely DO NOT sell anything.
It’s a very common design found in most serious antenna books and on dozens of HF-RX related websites.
Just look for the right core and use a 1:3 winding ratio, like my 9-3 turns.


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