Base CTE Saoliut LW 150 GPA

[Marconi]

Bob, here is the Tagra. I did this model with a physical gamma, and then I did the model with a simulated gamma finding a feed point match somewhere near the base of the radiator...to see if the gamma was the problem.

Then I did a Free Space model to check the accuracy and the models are not accurate showing an AGT understated gain of 0.548 = -.2.61 db error correction to the reported gain.These are the similar results to what I've been getting with these 7/8 wavelength extended models at 27.205 MHz.

Strange, I don't have any problem with these designs when I set them with a 3/4 wavelength radiator. The S4 design models show me the best gain among all the CB mono-poles antennas I've modeled, but this idea has disappointed me in my modeling and with a couple of buddies...that also found they could not extend the old CTE Larry 150 out to its limits in maximum length.

I see no reason why the 7/8 wavelength could not be tuned at 10, 11, and 12 meter at different lengths. This may be some silly thing I keep doing wrong here. I wish Swizzradios had done some video on the performance too.

I'm sorry now that I never tried making my Sigma 4 taller.

 

[Marconi]

BTW Bob, I noticed that the Tagra BA-104 looks very well built...did you ever consider one of these, or know anyone that had one of these?

 

[bob85]

I don't think you have a lot wrong with the models Eddie,
the 31+footers are too long & don't perform as well as the new vector 4000 or the old sigma4,

in my experimenting as I shortened the antenna signals went up but keep shortening & signals go back down,
same deal with the cone/radials, shorter is worse but I never tried them at full 1/4wave like the new vector,

as you sweep the radials up towards the monopole they cause the monopole to become electrically shorter than a monopole without the radial sleeve,

AFAIK nobody has worked out how much it needs lengthening to get it back to 3/4wave, are we talking an inch or 2 or is it nearer 12"

does the electrical shortening also effect the radials so they need to be a little longer too ?

all i can tell you for sure is manipulating the dimensions & retuning with the gamma changes tx & rx signal strength,
your models show the same trend as what you see in real life if you extend a vector out to 31ft+

 

[Mike Gammal]

I have one of these CTE Saliut LW-150 antennas it was boxed for 25 + years and sat in my shed. I am just getting back in the hobby and I am using it for 10 meters with a Yaesu 991A. The original instructions had no tuning info. I then searched the internet and found the CTE instructions with the cone height top adjustment at 90cm much shorter than the Sigma 4 and Vector 4000. I followed those instructions and then lowered the top tuning tip until the screw holding the 2 top tubes could no longer be lowered (The screw blocks it from entering the previous tube any further). I used a spectrum analyzer with a return loss bridge to sweep it that I had laying around from my previous career. I then tuned the gamma match for a perfect 1.1 SWR curve on 28.400. I reinforced each tube section with underground burial rated shrink tubing. My ground waves travel pretty far locally (about 60+ miles) with 100 watts and I have made DX contacts all over the world. The gamma match shorting bar is aligned where the manufacturer has stamped 2 dimples on the main radiator (as a guide) and has little play if if I go up or down a few millimeters I lose my tuning. I was always thinking the cone is 1/8 wave and the main radiator is 7/8 wave. I was under the impression the cone cancels out the 7/8 wave radiator and shortens it to a 3/4 wave antenna since it's grounded. From what I found on the net it seems closer in dimensions to the Tagra BT-104. When other operators ask about my antenna I just call it a 3/4 wave J-pole to keep things simple. I am curious if this a terrible configuration? I keep it only 1/4 wave above ground since I am always cleaning the snow/ice off the cone and I live on a hill which is kind of equivalent to a 60 foot tower. I am also curious if this was manufactured by Sirio for CTE international? Thanks in advance for any info to get this thing optimal. 73! Mike KB2YCF

 

[Shockwave]

The only thing I would add here is that if you have any problems retuning a Targa to a new frequency, do not be afraid to modify that fixed gamma tap point to a standard sliding bracket, to allow more tuning flexibility. There is nothing different about this gamma match, that makes it benefit from having a fixed tap point. It only simplifies tuning by removing one adjustment, for those not familiar with a gamma match.

PS: CTE is not affiliated with Sirio. Now if only we could get them to use the CTE tubing clamps, as opposed to a pair of machine screws, reliability would go up...

 

[Marconi]

I just now found some dimensions that I did not know about until I looked at a video in this thread. I will try this Tagra model again and hope I can eliminate some earlier dimension errors.

This may be an old thread, but it's short, and some may find it a good read.

Marconi