Is the Solarcon Max2000 5/8th di-pole like ?

[Marconi]

how much difference do you think not having a matching circuit with losses that closely model the real antenna makes ?

I'm not sure, but I seem to recall DB posting some results in the past comparing an antenna with and without his matching application using 4NEC2. IMO, I thought those results confirmed my sense of the issue...there was only a fractional difference in the db gain.

To be fair however, DB is the only one I know that can tell us how this works out for sure.

I think technically the match does have some small effect on the performance, but the difference just using my radio never showed much difference. I had no way to even consider gain back then...it was all about signals and comparing antennas.

 

[Marconi]

Eddie,
everything I have read says groundwave at higher frequencies don't travel very far from the transmitter due to ground attenuation, it used to amuse me hearing locals calling CQ groundwave when it was short hop skip,

Bob, I read some sites talking about Surface Waves describing and using similar words.

Not that I know anything special about all of these different waves, but I always understood that ground waves were not significant at 11 meters, and were only important at low frequencies...due to the long wavelength. I guess this may be a similar reason for your amusement.

I have read what seems like Surface Waves being very similar to Ground Waves in some of the words, definitions, and/or characteristics used to describe the terms.

Do you think they are about the same thing?

 

[Marconi]

Method 1: Find me an article that deals with surface waves and modeling that says as much. It has to be an article that has to do with modeling, not propagation like the page from your ARRL Antenna Book, a section that has since been dropped from the newer versions of the book all together.

DB, you posted about the lack of information on this subject earlier. I found the same thing in my search for information. I posted what I found that I thought might be pertinent and it looked like it was not important for the Amateur bands. Maybe as you note...that is why ARRL took the term out of subsequent editions.

Method 2: Have HenryHPSD tell me that what he told me (and everyone for that matter) in a previous thread was wrong. It was him that taught me that the only way to model local ranges is through using surface waves, and one of his reports was the first time I've seen surface waves modeled anywhere, and it was for a CB antenna, go figure...

I recalled Henry posting an addition to his article on the Sigma 4, but the whole thing has been taken down. I have a copy of the article, but unfortunately I did not make a hard copy of the added reports he posted.

There is your challenge Eddie. I am not interested in arguing with another opinion of yours on a topic that you know nothing about and haven't even bothered trying to understand before forming a set opinion that even the likes of God can't change. Its nothing personal, but I've learned the hard way that such discussions with you only create migranes for me. I have posted multiple times in multiple threads (including this one) exactly why I use Surface Waves and their differences from the more typical gain plot, some posts of which you directly responded to. You seemed to understand why said plots were being used then...

I must have missed it DB. Nothing personal, I'm often just looking for a better understanding of what my buds are claiming. Sometimes I post my opinions on a subject and sometimes I post the opinions of others that I find.

Try this link to eHam: http://www.eham.net/ehamforum/smf/i...plies=8;sesc=1516b9fe9a35205e8778108be48172be

I don't think this thread describes the Surface Waves perse, but it may be talking about the subject. I only looked at it once, but it may be supporting what you claim here DB, and I think it is about formulas and modeling different ways of determining gain or the effects of gain.

 

[Marconi]

DB, after reading the thread in eHam again this a.m. I'm not too sure they are talking about Surface Waves. It was late.

Sorry.

Back to trying to find something on modeling Surface Waves.

 

[RadioDaze2.0]

Interesting thing to add. A participating station in a "ground wave/surface wave/ line of sight" net last night noticed a signal jump (still an S0) from a switch between an Antron 99 and an IMAX2000 of another station. I heard myself it being said the Antron 99 was slightly higher mounted than the IMAX.

The distant station noticed a jump in volume upwards and the locals said there was no difference in signal.

My longest contact with an IMAX 2000 last night was 163 miles. There may well have been a little tropo enhancement. But I was speaking to stations over 100 miles away with ease most of the evening.

There was a guy using a Gain Master very close to the ground 140 miles away near the sea side who was coming in very nicely. All signals received were voice only R2-R5 S-0 signals on USB/SSB. In the UK there are "a lot" (relatively speaking given the hobby is largely in decline) of stations enjoying this way of operating. It fills the gap between the F2 layer seasons end (and the appearance of the low in the 11 year cycle) and the Sporadic E season starting in summer where we mainly talk 1-2K miles in Europe.

I have no idea what pattern the Solarcon MAX2000 (no radials, no chokes, no ferrites) just a 10m pole and 10m of coax... is creating given the many different models but it does ok.

 

[M0GVZ]

My longest contact with an IMAX 2000 last night was 163 miles. There may well have been a little tropo enhancement. But I was speaking to stations over 100 miles away with ease most of the evening.

There was a massive lift on yesterday. When I was coming home at 7am I was listening to one of my local repeaters GB3YC and there was a mobile to mobile conversation from a repeater over 200 miles away on the same pair coming in. They mentioned hearing some heterodyning from another repeater which would have been when GB3YC CW ID'd. I was hearing a lot of southern accents on 145.500. Must have a look at my APRS log and see who I heard.

 

[RadioDaze2.0]

It was supposed to be better earlier in the day as far as the forecast went but there was remnants of a lift in the "marginal" zone so it did not translate to a massive lift on 11M. You can see as of 18:00 the forecast was not great for the larger part of the UK.

This map gives a rough idea of what might be happening on HF. For HF sometimes it is right and sometimes not.

http://www.dxinfocentre.com/tropo_nwe.html

 

[DainBramage]

There was a massive lift on yesterday. When I was coming home at 7am I was listening to one of my local repeaters GB3YC and there was a mobile to mobile conversation from a repeater over 200 miles away on the same pair coming in. They mentioned hearing some heterodyning from another repeater which would have been when GB3YC CW ID'd. I was hearing a lot of southern accents on 145.500. Must have a look at my APRS log and see who I heard.

I can absolutely, positively guarantee you that what you heard on 2 meters at 200 miles distance was not "ground wave", more than likely it was tropospheric ducting.

... or the repeaters were linked.

 

[M0GVZ]

I can absolutely, positively guarantee you that what you heard on 2 meters at 200 miles distance was not "ground wave", more than likely it was tropospheric ducting.

Which is why my first sentence said "there was a massive lift on."

And the two repeaters aren't linked which I know for certain seeing as I'm involved in running GB3YC.

 

[Marconi]

DB, what do you think would happen to the Surface Wave results that you posted for the 27 mhz dipole, 5/8 wave, and the Vector...if you scaled the models to a broadcast frequency?

 

[Marconi]

I like DB 's new angle on signal strength at distance, it more closely fits my own experience,

antennas do perform differently especially over longer local distances,
I would be interested in a 5/8 vs vector surface wave measurement because in my experience the difference in signal between the best 5/8 antennas and a vector4000 at say 40 miles is not only a small fraction of a db from this location,

Bob, here are 3 models overlaied at the same mast height, showing gain and angle for a 1/2 wave CF dipole, a 5/8 wave GP, and a .75 wave vector type antenna with radials slanted up.

The 2nd overlay shows the same antennas at the same tip height.

To me the patterns and values are different from DB's surface results of course, but both methods seem to indicate similar trend relationships.

Henry commented something about the difference in mounting the models, equal mast heights vs. equal tip heights. So I did it both ways...and I was surprised to see such a little difference in comparison.

 

[bob85]

Eddie
I would possibly look at what is not in the models that is in a real install such as matching losses, local topology, nearfield obstructions,

something causes differences in performance between designs that seems to be unaccounted for.

 

[RadioDaze2.0]

I have had reports of bad audio quality since I have been using the IMAX2000. I suspect some kind of common mode issue that is not present (or at a relative level that causes issue at least) at low power but rears itself to some degree when I use 100W. People have said the audio is fluffy and there is a crackling when I de-key.

I changed a patch lead and magically it cleared up. I tested the old patch lead that was in line for continuity at home and it checks out fine. Even when I was testing and waggling the lead vigorously. So I don't think it was that. Though it does not account for why it cleared up., Maybe PL259 tolerances ? (I solder my own and do them properly). Seems odd that a tested lead should cause such a problem especially when your SWR is reading 1.4:1 throughout.

People keep saying I am over driving the amp. I am putting about 5 watts in. I have my RF output on the radio at 10 'o' clock and my audio meter peaks a S5 that is hardly over driving, if anything it is under driving. I have operated like that for ages so nothing has changed. Unless something is getting screwy in the radio itself it is only a £99.00 radio and it has done a lot of mobile service in and out of my radio box for the last 15 months. I opened the mic and the switch looks clean and dust free.

Odd thing is the same time people saying the audio is rough I am working stations on line of sight 100 miles + away so I don't understand it.

So I suspect there may be a common mode issue with the IMAX2000 but just enough to cause some minor audio problems. There is no question the RX is a bit noisier on my Alinco DR-135 radio I suspect it would be the case on any radio.

I will see what happens when I go out next time. I will try the Gain Master and see if anyone says the audio is rough.

Fact is there will be some common mode on the pole and line using a 5/8 wave without radials. The question is how much and how is it interacting with every other part of your radio system including the obvious one the radio itself or the linear.

I operate different setups (poles, heights, antennas, grounded or not) and QTH's so there are many more variables than base stations which can set and forget, to a degree anyway.

Being static mobile can have its challenges, if you get bored of running the same set up over and over again. I am in this hobby to be the best I can as an operator and a station and that does not mean using 1 set up and resting on your laurels.

I will try and get to the bottom of it.

 

[RadioDaze2.0]

Veering off topic a bit....I think this might be a radio or mic issue now. I apparently had a similar issue using the Gain Master yesterday evening. So I think I can reasonably rule out common mode causing the issues.

I am going to first try a spare but fairly unused new K-PO microphone I have in case the mic was the problem.

Odd problem really as a few locals say there is an issue crackling when I key up then it clears but I am still getting R5 reports 100-150 miles away. Maybe the issue is much louder to the locals.

It could of course be the radio itself, after all it is a quite cheap one and I has had a bit of a hard life the last 15 months in a setup that is not fixed.

Anyway will try and sort it soon.

 

[Needle Bender]

Veering off topic a bit....I think this might be a radio or mic issue now. I apparently had a similar issue using the Gain Master yesterday evening. So I think I can reasonably rule out common mode causing the issues.

I am going to first try a spare but fairly unused new K-PO microphone I have in case the mic was the problem.

Odd problem really as a few locals say there is an issue crackling when I key up then it clears but I am still getting R5 reports 100-150 miles away. Maybe the issue is much louder to the locals.

It could of course be the radio itself, after all it is a quite cheap one and I has had a bit of a hard life the last 15 months in a setup that is not fixed.

Anyway will try and sort it soon.

I've solved several similar issues by placing 12' of 66% RG-213 between radio & amp.