Homemade shortwave end fed wire antenna for grunding satellite 750

[stormtracker78]

I really need some good advice from our ham operators out there I bought a hundred feet of copper speaker wire wire to make a long wire antenna for my Grundig satellit 750 it'll be 50 feet north to south then 45° 50ft east and west I'm going to have it about 33 feet above ground where I'm having the problem is I want to be able to hook it into my satellite 750 through BNC that way I can use an mfj956 or their passive preselector 1046 I don't know which I need a balun or a un/un or a choke feed 1:1 or 4:1 or 9:1 I need something I can connect the end of the wire to that has a ground has the SQ connection that I can hook into the mfj passive preselector and then into my receiver I know connecting it to the antenna with alligator clips improves reception but I want to be able to hook it in either through the bnc directly on the receiver or on the passive preselectors so I need one of those balons or ununs to connect the antenna and the coax to the receiver and I'm hoping I will not need an antenna tuner although that's why I'm considering the 956 to my understanding I don't really need an antenna tuner for reception only the other question is I want to get all the bands I know different wire links increase reception on different bands but isn't there just good all-around size length for all the shortwave bands? ANY advice much much appreciated thanks

 

[prcguy]

I would shop for an inexpensive 9:1 end fed balun on Ebay or build one from some plans, then use that with about 45ft of your wire. That will make an antenna similar to the PAR end fed SW version which is a good performer and known standard for SW antennas. I would also use an effective 1:1 choke balun somewhere in the feedline.

This will give you an antenna that is outdoors and away from RF noises in the house and the choke balun will help keep noise induced on the coax shield from getting to the antenna and back into the radio. 45ft is also a reasonable size that most people can accommodate in a yard or along side a house and an adequate size for the SW bands and even BCB listening. You would not need an antenna tuner but a preselector may help the radio cope with stronger signals off the new antenna.

 

[ka3jjz]

True but a longer antenna will be more resonant down further in the band. 90 foot or so will work just fine down to 3 Mhz, and is within the OP's original 100 foot design. You might want to consider either a transmatch (notice I didn't call it a tuner as real tuners are not found at the station point) or a passive preselector but not both. That radio has a fairly hot front end, and it's not all that hard to overload it. Strongly consider a passive preselector if you have a lot of MW or FM stations nearby. A passive preselector acts like a tunable 'gate', allowing only those frequencies you've tuned to pass, and rejects others. It will do a certain amount of matching, but that's not it's primary role.

NEVER connect the antenna directly to the whip when you have another option, and in this case, you do. One little static zap and the amp that's likely at the base of the whip is likely to be dead. Assuming you get a passive preselector, the antenna goes to that (likely with a PL259) and you will then need a jumper between that unit and the S750's antenna jack, which is a BNC. There are PL259/BNC connectors out there (I used to use them myself) so that shouldn't be much of an issue. Mike

 

[stormtracker78]

Ty both very much!! Okay I understand I hook the end of the single wire to the 9:1 balon connect ground then hook the coax up to it(either rg8 or 58 or lmr 400 at the worst rg6 which I heard has a lot of db loss) then coax to either Radio bnc or passive preselector then jumper to receiver where would the choke balun go?? still researching those strange everytime I type choke feed in for search it brings up regular baluns?

 

[stormtracker78]

The grundig 750 is my starter radio ive had it for about 5 years I'm saving for an alinco dxr8 or dxr8st because I'm studying for the no tech license Ty FCC for doing away with memorizing Morse code just to start out in ham!!b v to those of you that can do qrp my hat's off to you my grandpa could do it with flashlights he learned it on the Navy ships!!

 

[ka3jjz]

Don't worry so much about the coax type. At HF, losses are so small as to be not worth mentioning, particularly in a listening application. At VHF and higher, it becomes more of an issue...Mike

 

[stormtracker78]

Awesome then rg6 would be the cost effective choice! now to double check on the balun it would be a un/un balun correct since I'm going to have a passive preselector and not an antenna tuner the random wire is unbalanced correct so the balun I should get should be a un/un? Someone told me that the mfj956 is both preselector and tuner but I really like from what I read about the mfj 1046 passive preselector which would you use for this project?

 

[ka3jjz]

Slow down a little here; you're clearly getting lost in the details. Let's start with the 9:1 transformer - it is often referred to as a magnetic longwire balun. One end of your wire goes to the balun, the other end is fed by your coax, and often these transformers have a ground lug. The other end of the coax comes down to the shack (I'll leave it to others to comment on the choke - I'm not entirely convinced that it's necessary - I've never had to use one). Plans abound on the web for these.

Now as to either the 956 or the 1046. Do you have any MW, TV or FM transmitters in your immediate vicinity? If you do, I would tend to think the 1046 would be a better bet, otherwise I'd go with the 956. Every RF environment is different and these would be general guidelines. It's difficult to make specific recommendations because of this. Mike

 

[WA8ZTZ]

Unless you really like experimenting with antennas, baluns, ununs, and the like, just get the PAR EF-SWL antenna.
In stock form it is about 45' long but you can extend it if you wish per the dimensions in your first post for improved performance.
RG-6 coax is fine but you will need adapters to mate the F connectors on the RG-6 to the SO-239 on the antenna matchbox and to the BNC at the radio. The 956 has the advantage of coverage of longwave and the AM broadcast band.
Have both the 750 and the 956 here and they work well together. The 750 is nice radio for casual listening.
If you eventually decide to get the Alinco you will soon realize that it is a lot more radio designed for more serious listening. The 956 will not enhance the Alinco as much as it helps the 750. Of course, the PAR EF-SWL will also work great with the Alinco.

 

[ka3jjz]

I was going to suggest that - and there's the advantage of an already wound transformer that you can fool around with the connections until you find one that works in your environment. You will need to experiment here - you won't harm anything if you mess a connection up...Mike

 

[nanZor]

Heh, slow down - no need to fill your shopping cart so fast.

You have the wire and height. You have a receiver, which like most has gain to burn - especially in the case of the '750, where punching in lots of attenuation and manually adjusting the rf-gain is a way of life with antennas that large.

So, yes purchasing an already-built 9:1 UN-UN is one way to go. Many of us like the Par / LNR Precision EF-SWL transformer for RX-ONLY.

Tip: since we're talking receive only, and diy, we can afford a little loss - a long forgotten technique of winding your own UN-UN is instead of using toroids, you can STILL use the old technique of wiring your own around 1-inch diameter PVC pipe!

Just look at the diagrams for the typical 4:1, or 9:1 transformers. Use a bifilar wind around the pvc for a 4:1, or a trifilar wind around the pvc for a 9:1. Most diagrams are for baluns. If you want an UN-un, (which you do), you can swap the coaxial center conductor and ground of the feedline the other way.

PVC forms instead of toroids are obviously much bigger, and do not perform as well as a *properly* made toroid, especially at higher freqs like 20+ mhz. But the bands that high are not that active these days, and for an rx-only standpoint, a little bit of loss as compared to a finely tuned toroid is acceptable.

Thus, you can go to your local hardware improvement store and whip one up pretty quick, espcially if you have some colorized pairs of wires around. (look inside some 3-wire extension cords for a 9:1 trifilar wind source)

I've made 4:1's around pvc so many times I can do it in my sleep. (12 to 15 bifilar turns).

Just keeping it in the diy aspect since you asked. Don't let lack of a toroid stop you!

 

[stormtracker78]

Ty guys so much!! I finished installing my line today and Mike thanks for all your help really everybody! going to get the balun you describe I live in Brownsville Texas so we have a ton of am Spanish stations and some FM not that much lw right now I have it done like a homemade zepp I cut a 6 in coax I striped coax cable about 3in bear Center copper wire cleard the outer aluminum mesh wrapd the end of the end fed speaker wire around that then hot glue in it all inside a empty seasoning bottle sealed that to make it rain proof got a coax connector and then hooked the coax cable into that and then ran it to my BNC in the receiver from what I studied in the plans it said Zepps do not need to be grounded but I would feel more comfortable with a grounded system which is why I totally agree with what Mike said about not connecting to the whip so thats is why I want to get that balun and also so it'll match the 50 ohm impedance. And ty hertzian I might try to make what you described God bless all our hams!!

 

[majoco]

Here's a very good article and other references to do it yourself and save a packet!

vk3il.net/projects-antenna/efhw-matching-unit/

 

[nanZor]

Just so you know - the "air core" diy balun is NOT high performance. Perhaps enough so for rx-only, or for the desire to build the entire antenna system from the home improvement store. There is a reason you don't see many articles on how to wind one.

The single pvc air core has the following problems:

* Restricted range. That is, the typical 12-13 bifilar turns (24 to 26 individual wire turns) wrapped around a 1-inch od (not critical) pvc pipe is really only good from about 80 meters to 20 meters.

* Range continued - To bring the range down to the 160 meter band, that means more turns, like 15 - 16 bifilar turns. Now 20m starts to suffer, but may be ok from an rx-only standpoint.

* Stray capacitance - especially from long-ish diy type connections to the coax and runs, this helps limit the upper frequency response, and also provides a good path for common-mode currents to flow. Usually not desired, thus additional ferrite choking is usually needed shortly thereafter.

* Not a balun, more of a transformer - since no antennas are really perfectly balanced in the wild, and since this design is not optimum, that - along with the stray capacitance of diy techniques, means one will typically not achieve a flat, and true 4:1 ratio across the spectrum.

Much like all voltage baluns, unless you find a good reason for this to be somewhat ok - like the NRFD antenna which purposely uses common mode discussed in another thread.

Just didn't want any balun-police to fire up the sirens.