Workman W-58 Help needed please!

[bob85]

i don't mean the models with radials eddie, im looking at the model where you just isolated the mast.

 

[BOOTY MONSTER]

it would be interesting to take a busted 99 or 2000 bottom section and within a few inches of the wire leaving the matching section replace the rest of the length with aluminum tubing and see what effects it has .

rob , does the 2000 cover 10, 11, 12, 15, and 17m without a tuner ?

 

[Marconi]

i don't mean the models with radials eddie, im looking at the model where you just isolated the mast.

It was late Bob, so I could have made a mistake in what I was trying to say. I agree the model without radials is not a sound design and the pattern shows that at the bottom of the radiator. IMP the exception could only be if the Imax/A99 tuning device is able to decouple the antenna from the support and the feed line in some modest way...that helps prevent what we see in the non-isolated model I posted. I'm just not convinced that an Imax/A99 is not the exception I noted above. I know our I-10K will not work worth a hoot unless we have nearly full 1/4 wave radials on it, no-way-no. Something is making the difference.

The idea I was intending to make was that the typical .625 radiator need radials if isolation was expected to work, or else the real Imax/A99 has some innate ability to help decouple the antenna from the mast, and if there were a feed line added to the mix, we'd have to add a choking device of some type, and that probably goes without saying.

The particular model you reference here was added as a comparison to the non-isolated no radial model only. I was thinking to show what could happen if the antenna was adequately decoupled in some way, similar to what I think the Imax/A99 tuning device can do, thus we don't need radials or isolation. This is not to say that isolation might not improve performance in some way, but that we see the Imax/A99 working good enough all the time, and when I tested my A99, I didn't see enough obvious difference to matter. I think I was talking you through my experiences at the time, via emails back in early 2011. That was when I got frustrated and accidental threw away all of my work notes and reports for my A99.

I agree, isolation alone without radials is probably not a good solution, just like your test have shown.

Can you give me some details of what you tested an how? I asked in my post above how the radials were done and what kind of antenna was being tested. Was that test the MultiMode antenna setup that is similar to the A99? I want to see if horizontal radials vs. slanted radials makes a difference. I might try again to model the feed line too, but I don't think I can do a choke.

This is off this subject a bit, but somewhere recently I think I posted a model of an Imax/A99 with various angles of degrees for the radials here on the WWRF.

That was an idea I got from a discussion on Cooper's Forum, of all places. At the time I was also checking out the report on the subject that Tech 833 did sometime back on the Imax with a GPK added. The models I made as a result seemed to support his idea that radials at 30* degrees showed a nice improvement over radials slanted at 45* degrees, the traditional angle most used, and similar results with horizontal and steeper angles of 20* degrees did not show to be working nearly as good as the 30* degree angle. For some time I doubted his report, but these models support his findings.

 

[Marconi]

it would be interesting to take a busted 99 or 2000 bottom section and within a few inches of the wire leaving the matching section replace the rest of the length with aluminum tubing and see what effects it has .

rob , does the 2000 cover 10, 11, 12, 15, and 17m without a tuner ?

Booty Monster, I took the matcher out of one of my A99's that was really acting badly. I found the coax shield and the center conductor were not tinned, and the solder joints for both to the coil were terrible jobs. The shield had those little wire hairs sticking out everywhere and I'm sure they were arcing and making plenty of RFI.

I fixed the solder joints, but I didn't attach it to any tubing, I used some extra wire I had, made it the same length as the antenna, and hung it in a tree. I put a 100 watts into it with the bottom hanging about 8' above the ground, and but for it being really low to the ground that virtually eliminated the RFI.

IMO, adding this matcher to a tuned replacement for the wire with much thicker tubing would be a mistake. I think part of the magic of this antenna design requires the characteristics that thin wire presents. I can't give you the words to explain why, but I believe this to be true.

Maybe Bob could help us understand better in this regard, if there's any truth to this idea.

BTW, I apologize to the creator of this thread for my contributions in Shanghaiing your thread.

 

[Needle Bender]

Alright Mister Marconi;



What's the possibility of having you model the Imax2000 in free space but with a 108" single counterpoise dropping straight down below it's mounting plate as if it were floating in space 100' above the space shuttle but with a very effective CMC choke in the coax 9' below the Imax2000 mounting plate?

I'd also like to see this model if the bottom tip of the 9' counterpoise were 45' above a good earth ground.

My thoughts are:
I'll grab a 4' piece of 2" diameter military fiberglass pole and install it in my metal push up mast 8' 6" below the top of the mast where it bolts all the way up into the Imax mounting plate.

Then I'll wrap a very effective coaxial CMC choke (5T x 4" form) around the fiberglass so the 9' of coax shield along with the 8' 6" of 2" diameter metal mast would provide right at a 1/4 wave counterpoise directly below the Imax, but fully RF isolated & insulated from the lower 45' of mast, leaving only a resonant 1/4 wave vertical counterpoise directly below the Imax.

I wonder what that would do to the pattern of that sometimes surprisingly good operating though noisy, fiberglass encased, vertically polarized, omni-directional, 27MHz .625 wire aerial?

 

[Marconi]

Alright Mister Marconi;



What's the possibility of having you model the Imax2000 in free space but with a 108" single counterpoise dropping straight down below it's mounting plate as if it were floating in space 100' above the space shuttle but with a very effective CMC choke in the coax 9' below the Imax2000 mounting plate?

I'd also like to see this model if the bottom tip of the 9' counterpoise were 36' above a good earth ground.

My thoughts are:
I'll grab a 4' piece of 2" diameter military fiberglass pole and install it in my metal push up mast 8' 6" below the top of the mast where it bolts all the way up into the Imax mounting plate.

Then I'll wrap a very effective coaxial CMC choke around the fiberglass so the coax shield & the 8' 6" of 2" diameter metal mast would provide right at a 1/4 wave counterpoise directly below the Imax, but fully RF isolated & insulated from the lower 36' of mast, leaving only a resonant 1/4 wave vertical counterpoise directly below the Imax.

I wonder what that would do to the pattern of that sometimes surprisingly good operating though noisy, fiberglass encased, vertically polarized, omni-directional, 27MHz .625 wire aerial?

To save me my confusion at this idea, if you'll post a simple drawing of this monster, I'll do my best. Please include the feed line and the choke location, and I guess the isolation length is 108", right?

I really don't understand the space shuttle idea at all.

 

[bob85]

i don't think the a99 or imax are much if any different to other no radial end-feds with regards mast/coax currents, they are notorious for it,
i don't think the a99 is any worse a performer than other 1/2wave endfeds either, they have proven to work very well compared to other antennas for some people and not others same deal with the imax,
imho most of the issues with a99's is how they are installed,

both garry and carl had lip biting rfi getting into everything even stopping his ts850's compressor working, isolation solved the issue and improved their signals a little,

if the isolation made the pattern change from what you show us in your not isolated model with most energy at high angles to a pattern more like the isolated with radials model you can see why the signals could have improved,

i posted a pic of garry's imax and how it was isolated the others were all done the same with wood + choke + radials, sloping 1/4wave wire, stock imax or mm's spiderplane,
mm2000 has a spiderplane on his a99 at the moment,

just adding the choke at different places along the coax did nothing at all for garry's rfi.

 

[Marconi]

i don't think the a99 or imax are much if any different to other no radial end-feds with regards mast/coax currents, they are notorious for it,
i don't think the a99 is any worse a performer than other 1/2wave endfeds either, they have proven to work very well compared to other antennas for some people and not others same deal with the imax,
imho most of the issues with a99's is how they are installed,

both garry and carl had lip biting rfi getting into everything even stopping his ts850's compressor working, isolation solved the issue and improved their signals a little,

if the isolation made the pattern change from what you show us in your not isolated model with most energy at high angles to a pattern more like the isolated with radials model you can see why the signals could have improved,

i posted a pic of garry's imax and how it was isolated the others were all done the same with wood + choke + radials, sloping 1/4wave wire, stock imax or mm's spiderplane,
mm2000 has a spiderplane on his a99 at the moment,

just adding the choke at different places along the coax did nothing at all for garry's rfi.

I can only suggest that my experience with several A99's that were not soldered well might suggest a case where we could get lip bit from RF. I never experience that however, and even though the antennas acted bad with TVI, I sensed they performed just as well as I would have expected. At the time however, I was not testing or comparing them.

if the isolation made the pattern change from what you show us in your not isolated model with most energy at high angles to a pattern more like the isolated with radials model you can see why the signals could have improved,

Bob, I also have tried to make the claim that this is not the way an Imax without radials would act, isolated or not. With the differences noted in the lack of performance for the model without radials and no isolation...folks would surely be able to notice the difference. I would think, 1.02 dbi @ 8* degrees is a big difference from 3.83 dbi @ 8* degrees and that would likely be noticeable.

Regarding Gary's RFI problem, I've heard stories both way with the choke, but I believe what you saw. Personally, I've never experienced much if any change with my best A99, no matter what I tried, isolation, chokes, or radials. This is precisely why I tend to say you might not experience the effects of doing anything constructive at the voltage node end of a 1/2 wave radiator.

Thanks for the details, I'll try several ideas on the Imax and maybe even the A99 model, and we'll see what Eznec indicates. I may post that however, in a new thread. I think d1g1man has lost all hope of getting answers to his questions.

 

[Robb]

rob , does the 2000 cover 10, 11, 12, 15, and 17m without a tuner ?

Needs some tuning on 17m. Doesn't work so great on 17m; but it is hard to argue with results as I have gotten with it there. 10, 12, & 15m needs only a skoash of tuning; just to clean it up - really. But it really works VERY well on those bands - no complaints at all.

I think if I were to run two 1/4 length radials for each of those frequencies, it would work better still. My house already looks like an antenna farm - lol! ATM - I just use 20 ft of metal mast below it. No plans to try it with radials.

 

[Needle Bender]

To save me my confusion at this idea, if you'll post a simple drawing of this monster, I'll do my best. Please include the feed line and the choke location, and I guess the isolation length is 108", right?

I really don't understand the space shuttle idea at all.

Oh it's easier than you think, I'm just guilty of over-clarifying.

The Space shuttle example was just for a free space model using a single counterpoise below it.

Simply place the Imax on a 54' fiberglass tower above average ground, with a single 9' counterpoise hanging straight down the tower, and disregard any feed-line.

 

[Marconi]

Oh it's easier than you think, I'm just guilty of over-clarifying.

The Space shuttle example was just for a free space model using a single counterpoise below it.

Simply place the Imax on a 54' fiberglass tower above average ground, with a single 9' counterpoise hanging straight down the tower, and disregard any feed-line.

Here is what I get with your Imax idea, I think, and they both look terrible. They are both at 54' to the mount with a 9' foot radial hanging down. One is over Average Real Earth, and the other is in free space.

View attachment NB's Imax idea.pdf

 

[Needle Bender]

Here is what I get with your Imax idea, I think, and they both look terrible. They are both at 54' to the mount with a 9' foot radial hanging down. One is over Average Real Earth, and the other is in free space.

View attachment 7295

Interesting! Now you have me wondering about the same thing except with a .625 WL counterpoise, and/ or a .75 WL counterpoise, again, both straight down.

One thing I did a couple years ago was to add insulators in the guy wires and added .75 WL sloping 55 degree wire radials below my Imax. Seemed to help performance.

 

[Marconi]

i don't think the a99 or imax are much if any different to other no radial end-feds with regards mast/coax currents, they are notorious for it,
i don't think the a99 is any worse a performer than other 1/2wave endfeds either, they have proven to work very well compared to other antennas for some people and not others same deal with the imax,
imho most of the issues with a99's is how they are installed,

both garry and carl had lip biting rfi getting into everything even stopping his ts850's compressor working, isolation solved the issue and improved their signals a little,

if the isolation made the pattern change from what you show us in your not isolated model with most energy at high angles to a pattern more like the isolated with radials model you can see why the signals could have improved,

i posted a pic of garry's imax and how it was isolated the others were all done the same with wood + choke + radials, sloping 1/4wave wire, stock imax or mm's spiderplane,
mm2000 has a spiderplane on his a99 at the moment,

just adding the choke at different places along the coax did nothing at all for garry's rfi.

Bob, these models with slanted down radials look terrible, and the closer to horizontal the radials get the better the model. I totally didn't expect this, so I'll have to redo the models. I could have made some mistake. Today was Mother's day, and I had a lot going on, which was not my usual routine, and I'm tired. So, I want to recheck this work before I post it.

You'll never believe anything I do or say again, if I show you how bad this Imax, isolated or not, turned out when slanting the radials down.

I've got to tell you though, that I was a little surprised to learn that you slanted the radials down on your Imax experiment, because I seem to recall MM200's antenna had horizontal radials with extended wires to make them full length 1/4 wave. But, I base that idea on a picture I recall and pictures can fool the eye, so maybe his radials were slanted down too. I also understand that the Imax GPK has the radials slanted down at about 40*- 45* degrees as the GPK comes. Am I right?

In the mean time you can check out my thread below, where I addressed a similar issue for the Imax with the GPK at various angles, and you will basically see what I'm seeing tonight, slanted radials on this Imax model are no-way-no. And, that flies in the face of the common wisdom and what you guys did in testing. I doubt you saw what these models predict, and the whole world knows that the Imax uses their GPK with slanted down radials. I don't understand this.

I'll do this project for the 22.5' foot Imax over tomorrow. Did you test both isolated and not isolated? I think MM200 did that with his 1/2 wave, but I'm not sure.

Here is the link to my thread on the Imax with radials at various angles.

http://www.worldwidedx.com/cb-antennas/138879-marconis-eznec5-model-imax-radials-various-angles.html

 

[bob85]

when i talked to CEBIK he told me that radial angle makes little practical difference to radiation angle until we fold the radials up towards the vertical, his upper hf monopole article seems to agree with what he told me,

all those models show the antena connectd to a conductive mast, what happens when the mast is isolated?

only the 90 degree radial model has the little circle i thought you said indicated the mast was grounded,

mm2000's spiderplanes are horizontal as you describe from the pics,
the others were sloping not by choice but convenience of what we had laying around,
( how can we reduce the rf on the mast/coax without buying materials for radials/isolator/balun)

 

[BOOTY MONSTER]

what did CEBIK say would happen if you "fold the radials up towards the vertical" ?

if the antenna is connected to earth ground doesn't that defeat any effort to isolate it from the mast ?