Recommendation for an antenna

[Token]

Originally Posted by nickcarr

This is why I didn't want to lay too much information in front of you to begin with. As you can tell, other members like to torture new guys.

Oh come on nick, I did not even throw in any math

Yes, it is entirely too easy to get very deep in this, and for most people it is totally unneeded. They are going to have a very limited area or capability, and “optimal” will be whatever they can get up.

Originally Posted by nickcarr

The point is to try stuff yourself. Every antenna configuration is unique. It's best to start with something that works and then go from there. If you take notes of your listening experiences, then you'll eventually learn what works best for you.

Can I get a hallelujah! I strongly agree. Try stuff out, keep some light notes to keep what you tried straight, don’t rely on memory.

If something appears deaf don’t be too quick to judge, it might just be conditions at the time. Until you start to understand what is going on don’t try to make too many adjustments. My advice is to get something like the antenna shortride has already purchased, install it as best you can, and play around listening for a while before getting wild with changing configurations.

One of the keys is to NOT get discouraged if it appears that at first you have not succeeded. Maybe you do need to change antennas or antenna configurations. But maybe you just need to get a feel for what HF monitoring is like also.

T!

[k3cfc]

Originally Posted by shortride

I just looked at a magnetic loop antenna that I really liked. Anyone ever build anything like this? I would love to have the plans for this one.

ASK AND YOU SHALL RECEIVE.

80-20m Magnetic Loop Antenna by Frank N4SPP

K3CFC

[nickcarr]

Originally Posted by Token

Oh come on nick, I did not even throw in any math

Yes, it is entirely too easy to get very deep in this, and for most people it is totally unneeded. They are going to have a very limited area or capability, and “optimal” will be whatever they can get up.

Well I just wanted the OP to get his radio and antenna set up BEFORE he realized how crazy we all are!

[shortride]

Originally Posted by nickcarr

Well I just wanted the OP to get his radio and antenna set up BEFORE he realized how crazy we all are!

I think you may have missed that one. I already pretty much had that figured out.

By the way! I received my R75 today and should have my Par Electronics EF-SWL antenna on Thursday. Now all I have to do is figure out how to get it up.

[shortride]

I had fun last night listening to the R75 hooked up to the Discone antenna.

[ridgescan]

Originally Posted by shortride

I had fun last night listening to the R75 hooked up to the Discone antenna.

Careful with that-I got snapped at a little here back in 09 for daring to say I was getting stuff off the discone on my r75. You will get most of the stronger signals minus a lot of the noise off the discone. It is a hunk of metal up outside after all. When I saw your post I hooked my d130j back up to the HF rigs (which I haven't done since because I put up a proper HF antenna) and I get a lot right now-but like VOA out of Africa on 15580 for example is very weak but it is there. You could almost say it acts like an active loop does in that the signals are not as strong but neither is the noise..and SWL is all about signal-to-noise, though a HF loop is designed to operate on HF and the discone obviously isn't.
One of the most knowledgable people on this forum came to my defense back then in this regard and pretty much shut them all up.
Bottom line is until you get the wire up you can have some fun on the discone

[shortride]

I'm going to have lots of questions I'm sure.

Like right now as I type I'm listening to 4 amateur radio operator carrying on a conversation. One in Riverside California, one in Rome Georgia and one of the others is in Long Island, New York. The 4th guy is in Nebraska. What's got my curiosity up is that I'm getting an S2 on one of them on a random wire length antenna that's laying on the ground in my back yard that's 45' long connected to the 500 ohm antenna input. I can hear them very well but I cannot hear them at all with the Discone antenna that's 35' in the air. This is on 14.295 USB.

[nickcarr]

The reason the discone antenna is not very effective is because it's barely part of the antenna system. The R75 is likely just using the shield of the coax for 90% of its antenna. There's a loading coil on top of the discone which pretty much terminates anything beyond about 25 Mhz.

The only part of the discone that the R75 is using is the radials which are connected to the coax shield. All in all, there just simply isn't much of a conductor. Also, you have some signal loss in the coax and depending on the type it could be quite high. If you were to add say a few 90ft wires on to the diagonal radials, you'd probably have a much better HF experience. These would act as a counterpoise and help bring in signals.



The wire is more effective because you have a longer element and it's better matched for the 500ohm input. It doesn't take much to have a receiving antenna. Heck, a (metal) coat hangar stuck in the back of the R75 makes a decent antenna. I know -- I tried it.

Obviously, this all depends on several factors as it's a system - not just one item that is making or breaking the set up.

As I recall Ridge, you added some wire to your discone which made it more effective.

[ridgescan]

Originally Posted by nickcarr

As I recall Ridge, you added some wire to your discone which made it more effective.

yup
AFTER I ran the straight discone for a year, I yanked the radials and used it as a feeder to a 50' line.
Like I said before, you'll get stronger signals with less noise on the discone. I tried San Francisco Aero on 8843 on the discone and it sucked compared to the wire but all kinds of BCs and stronger utilities come in cleaner than the wire but less strength.
I will start a thread in the HF antenna forum soon as I upload a couple videos I did on this. I want to keep this off your thread so as to no hijack it.

[LtDoc]

Nothing is 'negated', it's just not 'enough' antenna, too short for what you want it to do. It will receive something if the signal is strong enough, just don't expect it to be a very good signal when compared to an antenna designed for that band/frequency.
- 'Doc

[shortride]

Originally Posted by nickcarr

The reason the discone antenna is not very effective is because it's barely part of the antenna system. The R75 is likely just using the shield of the coax for 90% of its antenna. There's a loading coil on top of the discone which pretty much terminates anything beyond about 25 Mhz.

The only part of the discone that the R75 is using is the radials which are connected to the coax shield. All in all, there just simply isn't much of a conductor. Also, you have some signal loss in the coax and depending on the type it could be quite high. If you were to add say a few 90ft wires on to the diagonal radials, you'd probably have a much better HF experience. These would act as a counterpoise and help bring in signals.

The wire is more effective because you have a longer element and it's better matched for the 500ohm input. It doesn't take much to have a receiving antenna. Heck, a (metal) coat hangar stuck in the back of the R75 makes a decent antenna. I know -- I tried it.

Obviously, this all depends on several factors as it's a system - not just one item that is making or breaking the set up.

As I recall Ridge, you added some wire to your discone which made it more effective.

Well now you've really done it. Just when I thought I was beginning to catch on you tell me the only part of the antenna the R75 is using is the radials that are attached to the ground shield of the coax. If the shield is grounded, how is the antenna working at all?

[shortride]

I received my Par Electronics EF-SWL antenna today. Kind of anxious to get it up and do some serious DX monitoring.

[Jimru]

Shortride,

It's been awhile, do you have any news to share?

I am interested as I am going to setup my R-75 that has been dormant, in a box, for several years.

Now that I live in a house, as compared to my former location, which was a NYC apartment, I am looking to play SWL again!

Best,
Jim

[nickcarr]

Jim unless you live in a quiet location (i.e. out in the country) then I would suggest something like an active loop.

The Pro-1B or Wellbrook 1530 loops are ideal for SWL these days from suburban environments.

The loop has a pricey, initial investment cost but it's a one-time charge and very well worth the effort. For the size (a 1m loop) you can't beat the signal quality.

My Wellbrook loop:

[Jimru]

Hi Nick,

Thanks, I have been reading here about your experience with the loop and I will definitely consider it.

In fact, the area I am in is more suburban than rural, with houses close by, so RFI is a consideration.

Initially I think I will go the less expensive route, with a wire, as I have a ham buddy that has offered to help me and has wire to spare.

Once I see how that fares, I will consider the loop, indeed. I like the ability to null RFI by rotating and it's small footprint.

Meantime, I hope the OP comes back soon to tell us how his set up is going!

[nickcarr]

Yep, wire antennas are definitely cheaper and you can do just about anything with them for receive applications. I had a 300ft random wire up for a few years but the RFI drove me to the loop.

I installed my HF vertical and that helped quite a bit. The vertical was great above 5 Mhz and especially at 28 Mhz. The wire still won on < 5 Mhz but I didn't really listen that much below 4 Mhz anyway.

I took a chance on the loop. I was *very* skeptical that it could be *that* good, but I was proven wrong. It's definitely the best way to go in the suburban environment. Granted, my HF vertical can beat out the loop at 28 Mhz but it's a far larger antenna. (A Zero-Five 10-40 GP vertical.)

I don't use the rotator as much as I thought I would. Every now and then I'll turn it to verify the noise levels. Once you find the sweet spot, you don't really have to move it.

[pgnsucks]

Originally Posted by nickcarr

Jim unless you live in a quiet location (i.e. out in the country) then I would suggest something like an active loop.

The Pro-1B or Wellbrook 1530 loops are ideal for SWL these days from suburban environments.

The loop has a pricey, initial investment cost but it's a one-time charge and very well worth the effort. For the size (a 1m loop) you can't beat the signal quality.

Who might be a US domestic seller of the Wellbrook?

Also it doesn't look to be installed to high up and in a back corner...no line loss?

[nickcarr]

Originally Posted by pgnsucks

Who might be a US domestic seller of the Wellbrook?

You have to order directly from Wellbrook.

North American Versions

Originally Posted by pgnsucks

Also it doesn't look to be installed to high up and in a back corner...no line loss?

I'm not sure I understand your question. Can you rephrase?

[pgnsucks]

Originally Posted by nickcarr

You have to order directly from Wellbrook.

North American Versions
I'm not sure I understand your question. Can you rephrase?

I was trying ask if the Height of the antenna had any impact on performance?

With the antenna far away from the house would there be any Signal-loss?

Also what type of Coax did you use?

May sound like silly questions but you never learn unless you ask

[nickcarr]

It's okay I just didn't understand what you were asking the first time around.

For this type of antenna, height is actually not an improvement. The general consensus is that < 20ft is good. For LW or MW, you may want to be lower to the ground to improve the nulls in the loop. The higher up, the antenna becomes more omni-directional and you lose that extra advantage.

Coax is LMR-240 with BNC connectors on each end.

The antenna is not very far from the house - but in the corner of the backyard (which slopes downward slightly.) It's about 40ft away. You want HF antennas away from the house to reduce RFI. I'm lucky in that the spot it's placed is in the middle of four houses. So it has just about a 40ft buffer all the way around.

There's no signal loss here. The loop is an active antenna and thus has a preamp module which is powered by a small head unit.

Unfortunately, even at such a good spot, it doesn't make it completely immune to RFI.

Here's a good review with pictures of the first generation 1530 loop:

Wellbrook ALA 1530 active magnetic loop review