Baluns not working

I made a 49/1 balun. I checked it several times but its not working. When I plug it in to the transceiver the receive goes right down and can't hear incoming signals but if I bypass the balun and connect the long wire directly to the coax then I can receive.

I decided to buy a balun because I thought maybe I didn't build it right but the one I bought is giving the same results and no says tuning required written on the balun so I know it doesn't have to be tuned.

Why am I not getting signals when using baluns? 

I tested another type of balun unun just to get the same result again. What am I missing? There is obviously something I'm not doing?

Hi (sorry don't know your name yet),

Sounds a bit weird. If you had just tried the one you made only, then I would of asked for a photo so we could see if we could spot a possible issue. But as you've tried a couple of others and they're doing the same it probably isn't your handy work.

Presuming it's for CB/HF? And, that you have a radio connected to it with some coax and then a long wire, be that a random or a half wave length, strung from the balun / unun? If yes on both then other than possibly some dodgy coax or coax connection, or the long wire not connected to the hot terminal of the balun / unun, struggling to think of anything obvious you are doing wrong.

Neal

It would help if you tell us what antenna you are trying to tune random or half wave and on what band(s).

Deb

A 49:1 is only useful for a half wave end-fed antenna, as that presents a very high impedance to the radio without one. 

What length wire have you got attached, and what frequency/frequencies are you trying to use?

I have lost count of how many i have made for people and never seen this problem.
I would say it was a plug on the coax that has a problem sounds like a short.

Alan Pilot wrote:

I have lost count of how many i have made for people and never seen this problem.
I would say it was a plug on the coax that has a problem sounds like a short.

I think the OP may be confused as to the purpose of antenna transformers and where to use them. That's why a few days ago I asked whether random long wire or half wave, but no response yet.

Just in case the problem isn't yet solved...

A 49:1 unun is used to transform the very high impedance (2000 ohms +- ) of a half wave EFHW antenna to 50/70 ohms matched to the transmitter.

A 9:1 unun is used to match the lower impedance (450 ohms +- ) of a 'random' long wire. However, a random long wire isn't really random. It must be of a length that is NOT matched to any of the bands you wish to use. There are websites that tell you the best lengths to use for the HF bands. Here's one: https://www.hamuniverse.com/randomwireantennalengths.html

Deb

Spider281 wrote:

Why am I not getting signals when using baluns? 

I tested another type of balun unun just to get the same result again. What am I missing? There is obviously something I'm not doing?

Because the length of the wire you're using already presents a low impedance to the radio. When you add the 49:1 balun it alters it significantly so the impedance so signals are weaker.

The idea of a transforming balun is to reduce the feedpoint impedance to 50 ohms or near that the radio wants to see or to a level an ATU can deal with.

What is the SWR without the balun?

My understanding was any long piece of wire could be used with the 49:1 balun with no tuning required...

I found the issue with the grounding which wasn't on the antenna but on the transceiver so when any antenna is connected no matter what antenna it is as soon as the ground is connected receive goes weak but if you just have the center pin connected it receives fine, there is a problem somewhere on the transceiver. 

I'm using a different transceiver now where that issue is not present so the 49:1 balun works as it should but SWR is still high regardless of the length of wire used but I can tune it with the ATU. I'm using 40 & 20 meters mainly Occasionally 17 & 30 meters. My main uses are 20 & 40 meters.

No, I think you are confusing two types of longwire antenna.

A 49:1 (or 36 or 56 or 64:1) is specifically for matching the high feedpoint impedance you get from a half wavelength of wire.  This will have low SWR dips (if built and tuned properly) on the fundamental frequency and all harmonics.

For a random wire (not actually random, as it must not be resonant anywhere) you typically use a 9:1 unun with a tuner to get a good compromise match through the unun which is then bought in by the tuner.  Some commercial antennas might even use a 5 or 6:1 to suit their radiating element.

Two very different things, as you can see.

Hope that helps.

Spider281 wrote:

My understanding was any long piece of wire could be used with the 49:1 balun with no tuning required...

With respect, you need to read back on this thread and understand what baluns and ununs are designed to do. They are not a magic item that will automatically match any length of wire to a transceiver. Each is designed for a specific purpose as this video will explain.

Deb

This video explains why a 'random' long wire isn't random at all.

Deb

I think I have an idea still not 100% clued up on them.

With a 49:1 you normally use 66/67ft of wire and then i fold the end back to tune it on the 40m band.
With a tuner it will then work on most bands but not sure about 80 and 160m.
You can add a 110uh coil and about 2mtr of wire to the end of that to get 80m.

Thanks for the info. I probably need a 4:1 balun. I'd never get that amount in the trees because they are too close to the building I'm looking at 30 to 40 foot at best.

A 4:1 balun can work with 5.3 to 7.6  meters of wire. Or 9:1 8.8 to 10.8 meters of wire... so I'll need to get 4:1 or a 9:1

A 9:1 with 36ft of wire might work up to 80m ?.

Spider281 wrote:

I think I have an idea still not 100% clued up on them.

You have at least 30 feet?

Okay. Measure out exactly 29 feet of wire (be accurate it's important)

Hang the near end on the house or a nearby post using a bit of non conductive cord, and hang the far end to a post or tree with a similar bit of cord. It doesn't have to be high.

Connect a 9:1 unun to the near end of the wire, and to your coax into the house. Don't connect an earth or ground plane.

This will present an impedance of around 50/70 ohms to the radio and will tune to 40, 20, 15, 10. with a low swr.

Do you still have the material from your foundation course? It covers baluns and how/where to use them.

Deb

Thanks. I'll try that. From looking at the tree I'd say 30 foot is about the maximum I'd be able to do if I can get the wire right up on the top branch that will offer me more length. 

I still have my folder from the foundation course but its deep in storage so not easy to get in at the moment.

Spider281 wrote:

Thanks. I'll try that. From looking at the tree I'd say 30 foot is about the maximum I'd be able to do if I can get the wire right up on the top branch that will offer me more length. 

When you measure the wire, allow an inch or two for a small loop at the far to attach the cord, and a small loop a foot or two away from the near end for the same reason. By the way, you can have the near end hang down a bit if it makes installation easier, and that will help with space, too. But keep to 29 feet overall.

Another length you might try if you have room is 35.5 feet.

Deb