Antenna analyzers, where and why?

[Tokin]

So, good news if this calculator is correct.
If the 13' 6 11/16" measurement is correct for an electrical 1/2 wave length of coax I think I have just enough. If a 1/4 wave length would work I can make that too.
Bear with me folks, I have some issues that make me and math not get along very well. It's something I've struggled with all my life and it's not getting easier as I get older. I know I know I should find a different hobby hahaha. Thanks for your help and patience. Hopefully I'll learn something hahaha.

 

[Road Squawker]

Are you using RG-6/RG-8x?

That chart is misleading.
RG-6 has two different VF's.

https://www.febo.com/reference/cable_data.html

 

[Tokin]

Are you using RG-6/RG-8x?

That chart is misleading.
RG-6 has two different VF's.

https://www.febo.com/reference/cable_data.html

Actually I'm using Davis rg8x with a Vf of .78 the same as the belden 9914 they have listed.
Input frequency is 27.205

 

[Marconi]

This is the dummy load. Not bad.


View attachment 39053

Tokin, if your analyzer in your 2nd image your post #8 is attached directly to the DL, IMO you likely have a good DL

But, try this idea to see if the analyzer is stable over a range of frequencies. Scan across the entire CB bandwidth. Then go higher and then lower in frequency, than the CB band if you can. This will let you see how stable your DL is. If your results are close...then you know you have a reliable Dummy Load as a tool. Don't expect the results to be perfect as you move about in frequency, but the results should be close.

Then try this with several different jumper lengths and see how that goes.

You've heard talk about using a tuned jumper with your analyzer and getting mirror like image results. Then test the idea.

If you have a frequency resonant length coax jumper (tuned jumper) that you cut to a 1/2 wavelength, compare it to your analyzer connected directly to the DL results. If the jumper is tuned correctly and the values are equal or close to your DL results...then the jumper is good for the purpose intended at that frequency.

It is not necessary, but I made notes as I went along and recorded my results...so I didn't have to rely on my memory as I tested my ideas.

.

 

[Tokin]

Tokin, if your analyzer in your 2nd image is attached directly to the DL, IMO you likely have a good DL

But, try this idea to see if the analyzer is stable over a range of frequencies. Scan across the entire CB bandwidth. Then go higher and then lower in frequency, than the CB band if you can. This will let you see how stable your DL is. If your results are close...then you know you have a reliable Dummy Load as a tool. Don't expect the results to be perfect as you move about in frequency, but the results should be close.

Then try this with several different jumper lengths and see how that goes.

You've heard talk about using a tuned jumper with your analyzer and getting mirror like image results. Then test the idea.

If you have a frequency resonant length coax jumper (tuned jumper) that you cut to a 1/2 wavelength, compare it to your analyzer connected directly to the DL results. If the jumper is tuned correctly and the values are equal or close to your DL results...then the jumper is good for the purpose intended at that frequency.

It is not necessary, but I made notes as I went along and recorded my results...so I didn't have to rely on my memory as I tested my ideas.

.

Yes that pic is connected to the dl with a bnc to pl259 female with a barrel connector

 

[Marconi]

And I'm not happy at all with the screen omnthis rig expert. I will have to use it at night since you can't see shit during the day...

Check your analyzer settings. Maybe there are options for the screen display for daylight and dark.

 

[Marconi]

Actually I'm using Davis rg8x with a Vf of .78 the same as the belden 9914 they have listed.
Input frequency is 27.205
View attachment 39087

Tokin, this calculator agrees with the wavelength for a 1/2 wave at 27.205 MHZ = 433.849 inches with my Eznec modeling software.

Head's Up: I have nothing good to say about Davis RF Co.

 

[Tokin]

Check your analyzer settings. Maybe there are options for the screen display for daylight and dark.

I've looked and no further settings for the display unfortunately.

Tokin, this calculator agrees with the wavelength for a 1/2 wave at 27.205 MHZ = 433.849 inches with my Eznec modeling software.

Head's Up: I have nothing good to say about Davis RF Co.

The davis i tried just for a few jumpers. Didn't seem to be awful but wouldn't buy for Davis again.
Should I be measuring for electrical half wave as was suggested earlier or will a simple half wave measurement or will I need to experiment?

 

[Tokin]

I've looked and no further settings for the display unfortunately.

The davis i tried just for a few jumpers. Didn't seem to be awful but wouldn't buy for Davis again.
Should I be measuring for electrical half wave as was suggested earlier or will a simple half wave measurement work or will I need to experiment?

 

[Tokin]

Tokin, this calculator agrees with the wavelength for a 1/2 wave at 27.205 MHZ = 433.849 inches with my Eznec modeling software.

Head's Up: I have nothing good to say about Davis RF Co.

Ok so this is electrical 1/2 wave rg8x common at .66 velocity coax 11' 11 3/16" into my dl.
Not too shabby.

 

[Marconi]

Ok so this is electrical 1/2 wave rg8x common at .66 velocity coax 11' 11 3/16" into my dl.
Not too shabby.
View attachment 39122

I would say that is pretty close. Good enough for Government work.

However, I don't think I've seen RG8x with 0.66 VF.

 

[Captain Kilowatt]

However, I don't think I've seen RG8x with 0.66 VF.

Agreed. Any RG8X I have seen has a Vf of around 82% which is nominal for coax having a foam dielectric. Solid polyethelyne dielectric cable such as RG8 has a Vf of 66%.

 

[Tokin]

Yep rg8 it was. Sorry my dyslexia is real and it makes some things real difficult. Sometimes I have to read things multiple times and still not process it correctly. Still got me close enough to get the job done.
I put the antenna back on the tower/mast and I'll have to tilt it to make adjustments but I can test it at 17' to the radials.

 

[Marconi]

Tokin, I guess your antenna setting have changed by now, but have you tried using the 1/2 wave jumper...you showed us in post #40?

Is the antenna a Maco V5/8?

 

[Tokin]

Tokin, I guess your antenna setting have changed by now, but have you tried using the 1/2 wave jumper...you showed us in post #40?

Is the antenna a Maco V5/8?

I only had time to move the antenna before our daily storms rolled in so ill have to wait to work on it further. The storms have been rolling in early lately, around 2pm.
Yes its a maco v5000, same as the 58 but with a different base section.