Hy-Gain TH-3JRS Tri-Bander Beam 10, 15&20

[vitvoo1]

I'm about to buy a Hy-Gain TH-3JRS 3 Element Beam and I have a query if anyone can help please.

It says in one part of the Manula to wind the RF Choke 12 turns with RG8/U or RG58/U blah blah blah!

In another part of Manual it says wind the RF Choke from RG213/U 12 turns, I am using RG213/U for the run to Antenna when I put it up so the Choke will be RG213/U.

I am wondering if this will have an effect if indeed it should be RG58/U or does it matter?

Thanks for any help in advance.

[2E0UDG]

Hi,

The losses through the coax on HF affects the signals alot less than VHF, UHF and in particular above that!

I would use RG58 or similar for any HF antenna, purely for the ease of use!

Have a look at this site and work out the difference between the two coax cables your considering on the frequencies you are going to be using then decide for yourself!;)

http://www.ocarc.ca/coax.htm

Good luck!

[steveeh131047]

Common-mode chokes constructed with coiled coax have much lower bandwidth than those which make use of ferrite materials, so you have to make sure their peak performance is at the frequencies you want.

12 turns is too many for a choke which you want to cover 20m thru 10m. Wound in a 4" diameter, 12 turns would produce peak choke impedance at about 15 MHz, and by 30 MHz the impedance has dropped to < 300 Ohms

What you need is 6 turns of RG213 on a 4" diameter former. Wind it neatly as a solenoid, rather than "scramble wound". This will provide > 500 Ohms from 20m thru 10m.

There's no advantage in using RG58 other than ease of winding the coil. I would stick to RG213 simply because I don't have tabulated impedances for RG58.

73,
Steve G3TXQ

[vitvoo1]

Thanks Gents!

I thought about using the RG58 but I'm trying to get the most out of my 10w for the time being so have decided to use the thicker RG213 with the lower loss.

I did think about it only being a case of halfing the turns which you have confirmed, thanks Steve but I did not have a clue about lowering the diameter, good call!

Thanks also M3UDG.

Steve....so anything non conductive would be ok for the former?

Cheers

[steveeh131047]

I've used short lengths of 4" diameter plastic pipe in the past. I think I got it from my local DIY store, but I can't recall which section - rainwater downpipe, sewer, or plumbing etc :)

The nice thing about using a former is that you get repeatable and predictable results. If you "scramble wind" it's a lottery because you never know what the inter-winding capacitance is going to be and so you never know at what frequency it's going to be self-resonant.

If I were doing what you're doing I would make the RG213 one continuous length, including the length wound on the choke - that way avoiding extra connectors and the need to water-proof them.

73,
Steve G3TXQ

[vitvoo1]

Ok Steve..thanks again for that.

I'll pay the DIY store a visit and get the Pipe.

The one continuous length is a lot less hassle for me so that's good news. :)

It'll be a few weeks until it goes up or if we get a calm dry day maybe sooner here's hoping.

Dave that's a handy link thx, it's confirmed the best for me would be RG213, it's gonna give me the best part of 60w ERP (there or there abouts) according to the stats, very happy with that

Cheers!

[m0tca]

Hi All

When winding air wound baluns, I typically use a large plastic pop bottle. Basically leave the lid on so you cannot compress the bottle.

1. tape the incomming coax to the bottle (in a manner so that the coax looks like it is pointing up towards the bottle top).
2. Then wind as many turns on as you need around the body of the bottle.
3. Tape the outgoing piece of coax to the top of the bottle (aain pointing up.
4. then waste a roll of really cheap black insulating tape around the coils, until you have them all covered.
5. Simply remove the lid off of the bottle and colapse the bottle and remove it through the centre of your fresh new & very professional looking air wound balun.
6. waste some more tape at the four opposing points, sort of down the side under the bottom & back through the inside to the top (this stops the weight of the coax unwinding the balun over time.

Hope this helps someone & also not claiming it is original as the wife thought up how to do it! Much to my embarassment, she saw me trying to get tie wraps down between the bottle and the coil!

PS: If you need a wider balun the tesco special cider or larger bottle are about 5 or 6 inches across.

Best wishes
Trev M0TCA

[g3rfh]

Friend of mine in the Isle of Man used to wind his baluns on empty wine bottles. He said the best part of the job was emptying the bottles!
Ken G3RFH

[vitvoo1]

...eventually she's up! :D

Only 25ft from the Ground, Power Lines over House. :(

Straight run with 25 Metres of RG213 with 6 Turns on a 4 Inch Former, all Bands, 10, 15 & 20, SWR 1.4:1 average!

Not the best on 15 Meters, but very happy with results!

Thanks all for the tip's.

[vitvoo1]

...eventually she's up! :D

Only 25ft from the Ground, Power Lines over House. :(

Straight run with 25 Metres of RG213 with 6 Turns on a 4 Inch Former, all Bands, 10, 15 & 20, SWR 1.4:1 average!

Not the best on 15 Meters, but very happy with results!

Thanks all for the tip's.