Adding Wire To Endfed SWL Antenna

[ridgescan]

One of my two SWL receiving antennas is a 100' horizontal endfed (PAR EFSWL 9:1 transbox) wire configured in a "lazy L". I was contemplating adding wire to that system but if I add it to the far end, I'd have to make the total element a "U" shape.
What I wanted to ask here is, what if I connected an extra say 45' of wire to the near end of the 100' element right at the feedpoint, then ran that 45' wire out, underneath the 1st half of the 100' element? I'd then have two wires coming off the feedpoint. Would this improve reception, or would it kinda make this thing a multi-band? I want to try and increase signals basically.
Thanks.

 

[KB4MSZ]

If you really want to know what it is doing with given frequencies the best thing to do is invest in an antenna analyzer for the HF bands. This is especially true for SWL as you will be working with such a wide coverage of frequencies. For HF these units are quite inexpensive, say $70 or $80. I have one that covers 100 KHz to 60 MHz and can be connected to a computer for a nice chart of the entire MW through HF at the same time, or you can have it scan a range of your choosing. It will provide a graphic display of what your changes are doing with the antenna's performance, as well as what changes are being made to the impedance at the feed point. This makes it possible to revert to configurations that worked best for you. As to how the changes you described will affect the performance of your end fed wire only your ear can tell………or an analyzer.

 

[prcguy]

On a non resonant receive only SW antenna I'm not sure an antenna analyzer will tell you much about how the antenna is performing. For resonant types, yes everyone should have an analyzer. I'm a little familiar with ridgescans SW antenna and a better investment would be in an antenna analyzing software program. This will show radiation patterns, lobes, takeoff angles, etc, when making changes as described. There is a steep learning curve but its worth investing the time.

If you really want to know what it is doing with given frequencies the best thing to do is invest in an antenna analyzer for the HF bands. This is especially true for SWL as you will be working with such a wide coverage of frequencies. For HF these units are quite inexpensive, say $70 or $80. I have one that covers 100 KHz to 60 MHz and can be connected to a computer for a nice chart of the entire MW through HF at the same time, or you can have it scan a range of your choosing. It will provide a graphic display of what your changes are doing with the antenna's performance, as well as what changes are being made to the impedance at the feed point. This makes it possible to revert to configurations that worked best for you. As to how the changes you described will affect the performance of your end fed wire only your ear can tell………or an analyzer.

 

[ridgescan]

Thanks for the info. When I get a day I'll experiment.

 

[majoco]

I'm not overly sure what's in the PAR end box but I'm pretty certain it's not much more than an un-un with three terminals brought out to the top so that you can configure it which ever way suits you best - using the braid of the coax or else a wire connected to the local ground or one winding to the coax and the other joined to ground - one test will find out - but try it for a month or so in each way and keep notes before you decide. Again not sure what the ratio is of the un-un and as soon as you change the wire length you'll have to do it all over again! Un-uns are cheap and even cheaper if you wind them yourself and add a choke too.....

 

[prcguy]

The PAR SWL transformer has been measured as a 9:1 ratio and it works well down to AM BCBC and below, where some home made versions start to roll off much higher in frequency. I think someone should experiment on placing a feedline choke at various distances away from the transformer as the feedline can be part of this type antenna. There could be a magic length that perks up reception at some frequencies.

I would also use a choke at the receiver end to keep RFI from the shack from traveling up the coax, you can never have too many feedline chokes.

I'm not overly sure what's in the PAR end box but I'm pretty certain it's not much more than an un-un with three terminals brought out to the top so that you can configure it which ever way suits you best - using the braid of the coax or else a wire connected to the local ground or one winding to the coax and the other joined to ground - one test will find out - but try it for a month or so in each way and keep notes before you decide. Again not sure what the ratio is of the un-un and as soon as you change the wire length you'll have to do it all over again! Un-uns are cheap and even cheaper if you wind them yourself and add a choke too.....


View attachment 72530

 

[ridgescan]

I have both ground terminals shorted together then grounded right at the mount point which is a copper aerator pipe on the roof that is bonded to the water system in the building (I tested it).
Years ago when I bought the PAR I tried each Gnd. separately and found this way was best for noise.

 

[majoco]

Prcguy said:

The PAR SWL transformer has been measured as a 9:1 ratio and it works well down to AM BCBC and below, where some home made versions start to roll off much higher in frequency.

Any idea what the ferrite material is in the PAR box? My core shown above is type 43 which although it works well in the HF bands down to the AM BC band it's not so good below that I keep toying with the idea of going to 61 or 77 which supposedly has better VLF properties - any clues?

My downlead is choked at the shack end with about 12 inches of ferrite cores threaded on to the coax as well as that coax wrapped toroid up at the top. At the moment it's connected to an "Off-centre fed sloping delta loop" which seems to be working well. The lady at New York NAT D calling herself Gander comes in very well after dark on 8891kHz.

 

[prcguy]

Not sure what's in the PAR transformer. I believe 61 material has less permeability, so for the same amount of turns less inductance and higher frequency range. 77 mix is higher permeability but I see it used mostly for making chokes and RFI supression. There are other mixes like 73 or J that I've seen used for lower frequency transformers.

Here is an old article I found on short notice while waiting for my ride to the airport and it deals mostly with low frequency reception and various types of transformers. I was once trying to duplicate the performance of the AOR SA7000 on AM BCB reception and this article helped me a lot. https://www.qsl.net/wa1ion/bev/bb_antenna_matching.pdf

Prcguy said:


Any idea what the ferrite material is in the PAR box? My core shown above is type 43 which although it works well in the HF bands down to the AM BC band it's not so good below that I keep toying with the idea of going to 61 or 77 which supposedly has better VLF properties - any clues?

My downlead is choked at the shack end with about 12 inches of ferrite cores threaded on to the coax as well as that coax wrapped toroid up at the top. At the moment it's connected to an "Off-centre fed sloping delta loop" which seems to be working well. The lady at New York NAT D calling herself Gander comes in very well after dark on 8891kHz.

 

[ILSAPP]

Do you guys still advise to buy the EF-SWL for HF aero comms listening?
I have built a Loop on ground that gives me good HF reception but I'm wonder if getting the EF-SWL and remotely switch between the two will worth the money.

 

[ridgescan]

Do you guys still advise to buy the EF-SWL for HF aero comms listening?
I have built a Loop on ground that gives me good HF reception but I'm wonder if getting the EF-SWL and remotely switch between the two will worth the money.

Well, me being a guy who has two SWL antennas up there I say get it. If for nothing else, because it's fun to have more than one if you have the room. And the nice thing about the PAR is you can add more wire to it than the stock 44'.

 

[krokus]

Here is an old article I found on short notice while waiting for my ride to the airport and it deals mostly with low frequency reception and various types of transformers. I was once trying to duplicate the performance of the AOR SA7000 on AM BCB reception and this article helped me a lot. https://www.qsl.net/wa1ion/bev/bb_antenna_matching.pdf

That will make for some interesting reading.

Sent using Tapatalk

 

[ridgescan]

Yesterday I got up there and deployed an extra 45' of wire to the PAR. I connected it to the feedpoint and ran it out underneath the first half of the original 100' wire.
Propagation being what it is, I can't speak to signal strength improvement, but I want to say I may be seeing an improvement in voice copy within signals if that makes any sense. I have to give it more time to iron out any perceived differences-then again it could all be a coincidental uptick in propagation.
In my mind, I kinda fail to see that RF can even see this extra wire strung out parallel to the 100' wire-but then again, maybe it can?

 

[ILSAPP]

Thanks for the info.
Do you recommend adding more wire from the beginning of receiving it or later on after see how it performs with the standard length?
Do you use it in slope configuration, inverted L?

Well, me being a guy who has two SWL antennas up there I say get it. If for nothing else, because it's fun to have more than one if you have the room. And the nice thing about the PAR is you can add more wire to it than the stock 44'.

 

[ridgescan]

Thanks for the info.
Do you recommend adding more wire from the beginning of receiving it or later on after see how it performs with the standard length?
Do you use it in slope configuration, inverted L?

Start with the stock wire PAR gives you. You might be content with that. I have the 100' wire configured horizontally as what they call a "lazy L". It runs 45' north then turns and runs the last 55' west. So the 45' part gets stuff east-west of me, and the 55' part seems to capture stuff north/south. This is interesting since it's one element.
Then the extra 45' wire I added yesterday running underneath the first 45' of the 100' wire seems to increase "modulation" of signals especially east/west of me, making copy considerably cleaner.

 

[majoco]

Then the extra 45' wire I added yesterday running underneath the first 45' of the 100' wire seems to increase "modulation" of signals especially east/west of me, making copy considerably cleaner.

Ridgy - you may fine that making your 45ft extension may work better if you connect to one of the ground studs - it will then act as a counterpoise .

Once you have sufficient signal to make the AGC start to reduce the gain, then more signal won't make it any louder, but it will reduce background noise and may make the signal sound better as the AGC has a tendency to broaden the bandwidth.

 

[majoco]

.Prcguy....

..and here's a doc I found some time ago which rather put me off the "J" or 77 mix - and led me to use the 43 but even that's a compromise!

Ferrite Mix Selection - Palomar Engineers®

 

[ridgescan]

Ridgy - you may fine that making your 45ft extension may work better if you connect to one of the ground studs - it will then act as a counterpoise .

Once you have sufficient signal to make the AGC start to reduce the gain, then more signal won't make it any louder, but it will reduce background noise and may make the signal sound better as the AGC has a tendency to broaden the bandwidth.

That may more effective than what I just did-thanks Martin. Honestly I'm still with my ear to the radio trying to find out if what I did resulted in anything at all

Also Martin-if I add that counterpoise will it still be effective even though this antenna is well-grounded? Or should I "unground" the antenna in lieu of adding the counterpoise?

 

[ridgescan]

Well I kind of answered my own question tonight. I went up there and exposed the PAR box terminals, disconnected the hard ground, and tried every ground configuration possible. What I found was, when using only the "antenna ground terminal", or only using the "coax braid terminal", MW signal strength was cut in half but SW was a bit "cleaner". So what I wound up doing was, I left the hard ground disconnected, and went with what majoco suggested which was attach the 45' wire underneath the 100' element as a counterpoise. I attached that wire to the shorted ground terminals.
What I wound up with, is STRONGER MW signals and decent SW signals with a bit less of an inherent "crackling" I was getting with the hard ground attached
So thanks again Martin! MW may be more interesting now as I observed some new DX signals are there that were not before this change.
Bottom line, I think this thing is as good as it's gonna get so I'm pretty happy.

 

[majoco]

Well done, I'm happy to be of assistance even if it was a guess on my part! It always pays to experiment and sometimes you have a pleasant surprise.