PRC-150?

[glebo]

Do you have an amp with that?? If not, you're doing NVIS, which I'm sure you know. Try using a vertical on the upper part of the HF spectum. Vertically polarized signals will not attenuate as quickly as horizontal (however, they are omni-directional as far as RDF threats are concerned)...Are ya gonna be able to do any test shots to try and experiment??

If ya have room/concealment, also try the AS-2259 NVIS antenna that came out with the 104. Basicaly, two inverted V's fed from the same feed point. As long as the 150 can match it. (SWR wise)

Good luck..

[bravo22b]

Originally Posted by glebo

Do you have an amp with that?? If not, you're doing NVIS, which I'm sure you know. Try using a vertical on the upper part of the HF spectum. Vertically polarized signals will not attenuate as quickly as horizontal (however, they are omni-directional as far as RDF threats are concerned)...Are ya gonna be able to do any test shots to try and experiment??

If ya have room/concealment, also try the AS-2259 NVIS antenna that came out with the 104. Basicaly, two inverted V's fed from the same feed point. As long as the 150 can match it. (SWR wise)

Good luck..

We don't have any amps. As you say, I expect to be doing NVIS so I am trying to expand my knowledge base of improvised antennas that will fit inside of a building but also get me some good upward radiation.

I think we are going to have a BRS set up within about 20 kilometers as a backup to our longer shot. That way if the teams are unable to get comms using NVIS they can at least have an alternate station to pass up their reports to.

My tentative plan is to start off with a couple different NVIS antennas and then if I can't get anything with those try a 1/4 or 1/2 wavelength vertical on the closer BRS. Being as we will be hiding out in a building for about 24 hrs. it should give us plenty of time to play with different configurations.

[Badger52]

Originally Posted by glebo

If ya have room/concealment, also try the AS-2259 NVIS antenna that came out with the 104. Basicaly, two inverted V's fed from the same feed point. As long as the 150 can match it. (SWR wise)

Good luck..

Glad you mentioned that; good catch. This is a rather neat antenna and has some EMCOMM uses which I've been exploring however, as dimensioned, it either needs loading coils or has to be recut a good bit longer for civ use (or use a heckuva good tuner). Not sure how much VSWR the 150 handles w/o its coupler but I recall seeing some pretty high numbers outside the 5.9 or 9.1 MHz areas as presented at the feedpoint.

bravo22b, I'll assume hiding means just that & roof-top footprint isn't an option, or is that available as something for the AS-2259, which I think is now Harris' RF-1936?

Good luck; watching with interest (again).

[bravo22b]

Originally Posted by Badger52

Glad you mentioned that; good catch. This is a rather neat antenna and has some EMCOMM uses which I've been exploring however, as dimensioned, it either needs loading coils or has to be recut a good bit longer for civ use (or use a heckuva good tuner). Not sure how much VSWR the 150 handles w/o its coupler but I recall seeing some pretty high numbers outside the 5.9 or 9.1 MHz areas as presented at the feedpoint.

bravo22b, I'll assume hiding means just that & roof-top footprint isn't an option, or is that available as something for the AS-2259, which I think is now Harris' RF-1936?

Good luck; watching with interest (again).

Each of our teams will be in a different building ranging from a 3 story "hotel" with a nice big flat roof with a parapet to smaller 1 and 2 story buildings with pitched roofs. Given that our mission calls for being undetected, each team has to come up with a plan for their antenna that accommodates the size and type of building they are in. A team in a building with a flat roof and a parapet may be able to get away with installing an antenna up on the roof, a team in a small building with a pitched roof probably needs to plan to keep it inside the building. Given the physical size of a 1/4 wavelength antenna in the 2-8 MHz range, not too many teams are going to be able to plan to erect a dipole, or an inverted V.

Part of the goal of our training is to increase the complexity as the teams become more proficient. This exercise should make them think a little bit and hopefully learn more about how to do HF.

[glebo]

b22,

given the low freq you're operating on, which will dictate resonant antenna length (which will be long), you can also alter the physical characteristics of the antenna. Just make sure each leg is as symetrical as you can get it. I've seen "V"'s/doublets legs zig-zagged to fit in a confined space and they worked. You may also try "coiling" each leg around a 6" dia. or so piece of PVC pipe to. Make sure you have even spacing on the wire, hold in place with tape. Obvioulsy, the less altering, the less you'll be taking away from antenna characteristics and efficiency.

At that range, you'll be somewhat omni-directional anyway.

You should still be able to get out some good useable signal from the antenna..

As always, it all depends on how well the freq's you're using are propping though. You can have all the power in the world, best antenna, but if the freq's not there...you're wasting your time.

[Badger52]

Originally Posted by glebo

given the low freq you're operating on, which will dictate resonant antenna length (which will be long), you can also alter the physical characteristics of the antenna.

Fellow I know is residential "lot-size constrained" and has a double-bazooka, resonant at 3.9 and has it running around in a very lazy, but very symmetrical "W". He does his inside 300-mi thing with no problem (other than the aforementioned radio gods having a bad day). Not specifically to b22's situation but you've shown benefits of getting one's head out of the dicta.

b22's variety of site challenges makes this interesting.

[glebo]

Originally Posted by Badger52

Fellow I know is residential "lot-size constrained" and has a double-bazooka, resonant at 3.9 and has it running around in a very lazy, but very symmetrical "W". He does his inside 300-mi thing with no problem (other than the aforementioned radio gods having a bad day). Not specifically to b22's situation but you've shown benefits of getting one's head out of the dicta.

b22's variety of site challenges makes this interesting.

awsome, good deal. "Bazooka"...I remember that term..cool.

You'd be surprised at what ya can do with an antenna...as long as you don't get to crazy..

[bravo22b]

Originally Posted by glebo

b22,

given the low freq you're operating on, which will dictate resonant antenna length (which will be long), you can also alter the physical characteristics of the antenna. Just make sure each leg is as symetrical as you can get it. I've seen "V"'s/doublets legs zig-zagged to fit in a confined space and they worked. You may also try "coiling" each leg around a 6" dia. or so piece of PVC pipe to. Make sure you have even spacing on the wire, hold in place with tape. Obvioulsy, the less altering, the less you'll be taking away from antenna characteristics and efficiency.

At that range, you'll be somewhat omni-directional anyway.

You should still be able to get out some good useable signal from the antenna..

As always, it all depends on how well the freq's you're using are propping though. You can have all the power in the world, best antenna, but if the freq's not there...you're wasting your time.

Thanks for the advice, I find it very educational. Since my guys will have some time to kill during the surveillance portion of the mission (rest plan, what rest plan?) I may try to set up something like you describe.

As far as freqs, we have our VOACAP prediction which shows we should be able to have good comms between 3-6 MHz, but whether the spectrum management people give us the right freqs is, unfortunately, out of our hands.

[Badger52]

Originally Posted by glebo

awsome, good deal. "Bazooka"...I remember that term..cool.

You'd be surprised at what ya can do with an antenna...as long as you don't get to crazy..

A double-bazooka made right, vice the other 999 versions somewhere on the internet that don't take velocity-factor into account (with subsequent complaints that they don't work). Then again, it might be too heavy to haul in unless you get some super low-loss high-$ low-payload coax like DoD uses all the time. Oh. Wait...

..but whether the spectrum management people give us the right freqs is, unfortunately, out of our hands.

IIRC that's on the standard list somewhere of a signaleer's alibis. 'Course 5x5 is better than an alibi anytime.

I like glebo's idea of wire around a PVC, assume here basically talking about using loading coils to make the wire electrically longer than it really is, ergo more portable & "hide-friendly" no?

[MD2colo]

I really like these 150s...
Been using a pair of them to send data to a distance of about 300 mi here in A-stan. Not sure when/if 19th group with ever get them, since 137s fill the HF role but they are cool for a non-SOF ALE radio.

THe third generation ALE works great... better than I expected.
Base station has a 2259 NVIS antenna and the outstations have the radios in the vehicles, coax out to a cobra head with 18' of speaker wire off of the hot side and the negative post grounded to the truck frame. wire is ran up an FM antenna and tied to the back of the truck. not the sexiest thing you ever saw, but it works. Hell of a lot more lo-pro, also.

Used the VOACAP online prediction website to get in the ballpark, freq manager did his best to hook me up but I was impressed with how easy the VOACAP is to use... for me the other programs like DXprop and the like are too difficult to understand. probably my fault tho.

[bravo22b]

It's been a while since I have posted anything on this, but I thought I would add something as my unit increases its' proficiency and experience with using the 150. Our drill this past weekend took us to Camp Santiago, Puerto Rico and one of our training goals was to do HF shots back to Hagerstown, MD. Total distance was approximately 2640 kilometers.

We had extremely limited training time and real estate, so we weren't able to get each LRS team set up with their own antenna, but our commo section got a sloping vee set up using a Harris RF-1940 antenna, and got very good link quality back to Hagerstown. I don't have the LQA scores handy, but it was good enough link quality over 3G ALE to use digital voice without a lot of problems.

The antenna was set up on a hilltop with the apex about 18' off the ground on a OE-254 mast, legs approximately 75' long (whatever the standard length of the RF-1940 leg is), and spread about 50'-60' apart.

I'll see if I can get any more details and post them if I do.

[69harley]

Originally Posted by bravo22b

It's been a while since I have posted anything on this, but I thought I would add something as my unit increases its' proficiency and experience with using the 150. Our drill this past weekend took us to Camp Santiago, Puerto Rico and one of our training goals was to do HF shots back to Hagerstown, MD. Total distance was approximately 2640 kilometers.

We had extremely limited training time and real estate, so we weren't able to get each LRS team set up with their own antenna, but our commo section got a sloping vee set up using a Harris RF-1940 antenna, and got very good link quality back to Hagerstown. I don't have the LQA scores handy, but it was good enough link quality over 3G ALE to use digital voice without a lot of problems.

The antenna was set up on a hilltop with the apex about 18' off the ground on a OE-254 mast, legs approximately 75' long (whatever the standard length of the RF-1940 leg is), and spread about 50'-60' apart.

I'll see if I can get any more details and post them if I do.

Good job. What can you tell us about the setup at the base station Hagerstown?

[bravo22b]

Originally Posted by 69harley

Good job. What can you tell us about the setup at the base station Hagerstown?

Our BRS in Hagerstown also had a sloping vee antenna, set up on the roof of our building. Initially when they were trying to make comms at night, PR could hear Hagerstown but Hagerstown could not hear PR. In the morning, the antenna in PR was adjusted and they were able to get good traffic both ways with voice and Tac Chat. I think the highest LQA was a 35.

One of the theories being discussed is that there is a large solar panel array (several acres) and power lines just south of our building in Hagerstown, on the transmission path, and that there may have been some EM interference that was affecting the weaker incoming signal more than the stronger outgoing signal. It's hard to know, but it sounds plausible.

Both stations were using un-amplified PRC-150's on high power (20 watts) and the Harris RF-1940 antennas.

[69harley]

Those solar panels may have been a source of interference, but being in the transmission path is of little consequence. The electrical noise, whether it is in the path or not, may sort of drown out the weaker signal of the distant station, but does not absorbe or 'block' the transmission.

Sort of like while peeing in the bathroom, I cant understand what my wife is saying in the next room. But she can hear me just fine.

Did reliable two-way comms ever happen at night between PR and Hagerstown?

PR to Hagerstown on two 20 watt radios and what are basically a manpack dipole antennas is pretty good.

How HF is typically worked is the base station will have larger, higher gain antennas and amplifiers, and the out stations have smaller, lower powered radios and antennas with less gain. The base station antennas are typically very large, this allows them to reliably receive the weak transmissions from the outstaions. The amplifiers allow the base stations to blast out to the smaller antennas used by the out stations. Having the same setup, manpacks and small dipoles (sloping v), is challenging and on the fringes of workable link margins.

Even though the antenna in PR was adjusted in the morning and then comms were established, I suspect the real cause was the sun came up and polarized the ionosphere. IME. that shot is much easier to close the loop on during the day than at night.

Good job. Glad to see units learning and using HF.

[Badger52]

Originally Posted by 69harley

Even though the antenna in PR was adjusted in the morning and then comms were established, I suspect the real cause was the sun came up and polarized the ionosphere. IME. that shot is much easier to close the loop on during the day than at night.

Good job. Glad to see units learning and using HF.

Cool stuff indeed and I agree. Certain bands can be very sensitive that way, and just a few more degrees of sun above the horizon - literally wait a few minutes - can make a huge diffference.