Help with matching transformer?

jvic · #1 (**permalink**) 11-29-2012, 8:31 AM

We have a number of matching transformers at work. I am 99.9% ignorant on these and would like to know if they have any value or use?

They are PN TAS100-545N/A made by South Midlands Communications.

Info from their webpage:

The TA Series of transformers are rugged and lightweight, ideal for inclusion in tactical and transportable HF antenna systems. Combinations of power rating and impedance transformation ratio provide the antenna designer with a wide selection of units to complement most antenna configurations.

Broad band 1.5 to 32 MHz
Power - 50 Watt to 1 kW
Lightweight fibreglass body
Tactical or transportable application

The transformers are housed in extremely strong fibre glass bodies, hermetically sealed with low loss resin and suitable for any commercial or military environment. The input coaxial connector is protected within the specially formed body and the transformer itself is grounded as an added protection against static and lightening induced EMF’s. We sell a TAS version, the spigoted model of the TA series for use with our masts.

Here is a link to them:

South Midlands Communications Ltd - TA Series - Tactical HF Antenna Matching Transformers

LtDoc · #2 (**permalink**) 11-29-2012, 11:48 AM

The first thing that comes to mind is what kind of connectors do they have, and the model number? I can't tell you what they are worth.
- 'Doc

~~kb2vxa~~ · #3 (**permalink**) 11-29-2012, 3:47 PM

You're slipping Doc, click on the link. (;->)

They have value and use alright being rugged commercial and military grade baluns. The key as to use lies in the impedance of the unbalanced side, 75 ohm for a dipole, 300 ohm for a folded dipole and 450 or 600 ohm for a rhombic depending on its particular design. I can't say about the others but there are a number of balanced antennas such as a Sterba curtain and there you have to do a little homework to determine the feed point impedance.

LtDoc · #4 (**permalink**) 11-29-2012, 5:53 PM

Ha!
You're right, it slipped right past me. But still don't know what kind of connectors.
- 'Doc

mmckenna · #5 (**permalink**) 11-29-2012, 8:10 PM

Guys,

JVIC posted the model number in his post:

Quote:

Originally Posted by jvic

They are PN TAS100-545N/A made by South Midlands Communications.

According to the website he linked to, that is a 1 Kilowatt 450 ohm balun. The only thing that isn't for sure is the connector type. Likely the "N/A" on the part number tells that story. The web link shows them available with BNC, N, UHF or type C connectors. The first three are pretty easy to do. Finding a C connector is going to be a bit harder but certainly not impossible. There is, also, the matter of the color, but I doubt JVIC cares about that so much.

~~kb2vxa~~ · #6 (**permalink**) 12-01-2012, 12:33 PM

"But still don't know what kind of connectors."

I'll save you the trouble of going back to the page and scrolling down to the bottom. (;->)
Connectors BNC, N, UHF, C

acyddrop · #7 (**permalink**) 12-05-2012, 6:42 PM

'm assuming the N/A would imply there aren't any connectors but screw terminals (or similar) to attach the ladder line to. Of course you know what they say about assumptions because the literature implies it takes 50 ohm input..

mmckenna · #8 (**permalink**) 12-05-2012, 7:11 PM

...and the web page shows it available with BNC, N, UHF or C. No mention of screw terminals, but screw terminals on both sides of a balun would likely be pretty odd.

acyddrop · #9 (**permalink**) 12-05-2012, 8:59 PM

I'm new to ham radio and particularly new to the use of 450 ohm ladder line but I've never seen a 450 ohm balanced line ladder line terminated with a BNC, N, C or UHF coax connector. So I was just guessing that the N/A meant they had another terminating solution, since there's no photos and screw termination or similar made the most sense. I also made the leap that since it's a balun that the feedline side is the bal(anced) side and the un(balanced) side is the radiating side. And since coax is GENERALLY 50 or 75 ohm and not 450 ohm (though I am well aware of some oddball versions of 93-95 ohms, but they're fairly uncommon and not used for RF so far as I know) .. That left ladder line as the most common and yeah, no idea how you'd get a coax connector on that.

Quote:

Originally Posted by mmckenna

...and the web page shows it available with BNC, N, UHF or C. No mention of screw terminals, but screw terminals on both sides of a balun would likely be pretty odd.

mmckenna · #10 (**permalink**) 12-05-2012, 9:03 PM

A Balun is short for BALanced - UNbalanced. Coaxial cable is an unbalanced feed line, and ladder line is a balanced feed line. Baluns are used to switch between the two. If you have a center insulator/balun like this, you'd be going from a coaxial "unbalanced" feed to a balanced antenna. You could go the opposite way.
But, by definition, a Balun is balanced to unbalanced. An UnUn would be a transformer that joined two unbalanced lines of different impeadance, like a 50 ohm coaxial to a 75 ohm coaxial.

acyddrop · #11 (**permalink**) 12-05-2012, 9:16 PM

Yeah I know I went back and edited mine (I make these things for projects trying to make a perfect one for my needs), in fact I have an Unun project on this forum. But on the other hand, you're right the coax could be the unbalanced side and the radiator the balanced side. I forgot to consider that since I've been doing so much with unun's lately.

Quote:

Originally Posted by mmckenna

A Balun is short for BALanced - UNbalanced. Coaxial cable is an unbalanced feed line, and ladder line is a balanced feed line. Baluns are used to switch between the two. If you have a center insulator/balun like this, you'd be going from a coaxial "unbalanced" feed to a balanced antenna. You could go the opposite way.
But, by definition, a Balun is balanced to unbalanced. An UnUn would be a transformer that joined two unbalanced lines of different impeadance, like a 50 ohm coaxial to a 75 ohm coaxial.

mmckenna · #12 (**permalink**) 12-05-2012, 9:48 PM

Cool. What are you using the UnUn's for?
I had access to a few hundred feet of .750 75 ohm hardline once and was going to make a pair, but never did. Aluminum coax is a pain to deal with....

acyddrop · #13 (**permalink**) 12-06-2012, 12:15 AM

I've been using them on a 43 foot home built vertical antenna, trying to find the right characteristics on the bands/frequencies I use most. The project I put up here is actually a very good wideband unun design that should handle full legal limit.

Quote:

Originally Posted by mmckenna

Cool. What are you using the UnUn's for?
I had access to a few hundred feet of .750 75 ohm hardline once and was going to make a pair, but never did. Aluminum coax is a pain to deal with....

~~kb2vxa~~ · #14 (**permalink**) 12-06-2012, 11:11 AM

Oh dear, to begin with N/A means not applicable. These baluns are standard design, none I know of have screw terminals. Take another look at the photo, at the top you'll see the support point. The "wings" below it are support points for a wire antenna or open wire ladder line not to be confused with insulated twin lead or window line. On them next to the body are the electrical connections, often they come with solder lugs as shown in the bottom unit.

How did the un-un discussion migrate to this thread?

acyddrop · #15 (**permalink**) 12-06-2012, 7:03 PM

N/A does not stand for "not applicable" no way! It stands for Ninja Assassins!

mmckenna · #16 (**permalink**) 12-07-2012, 12:01 AM

Narcotics anonymous. Nerds abound. Never aware. Now annoying....

jvic · #17 (**permalink**) 01-03-2013, 8:17 AM

I am sorry I lost track of this thread with the Holidays. I am attaching photos of the parts.

We would like to dispose of these, but would rather not throw them away. We have, I believe, 14 of the units. If anyone is interested, you can have them for free, but you have to pick them up in Bennington, Vermont or have a UPS or FedEx account number to bill the shipping to.