?? Tuning the new Maco V58 ??

[Rok55]

Finally got the Maco up and temp coax run. Set up for tuning is antenna 10' off the ground, 18' RG8X to an Astatic SWR Meter, 100' RG8X from Meter to Uniden 880.

Initial check at radio showed 1.12 on Ch 40 and 1.76 on Ch 1 using the Uniden on-board SWR calibration.
Initial check outside at the Astatc meter showed flat response on Ch 40 and 1.7 on Ch 1.

Adjustment of the ring lead (rather than overall length) resulted in 1.6 across the band on both the Astatic and on-board calibration.

Is that good enough or should I now strive for lower SWR by adjusting total length of the vertical?

Thanks ......... Rocky

 

[543_Dallas]

I'd try to get as low as possible across the band. If it's perfect you should end up with equal swr on 1 & 40 with a slightly lower reading on ch20. Keep in mind it may change some when you raise the antenna.

There may be no noticeable difference in performance after taking the extra time but the finals used in newer radios are fragile so having a good match is important. Take your time and do the best you can. If not you'll have regrets later.

 

[Needle Bender]

You should check tuning with the radials at 18' above ground and using an electrical 1/2 wave of coax.
That's the manufacturer's stated Velocity Factor (VF) multiplied by a 1/2 wave of 18'
which equals 12' of RG-8 or RG-213 @ 66% VF
13.5' @ 75% VF
or
15' 4.5" using 85% VF LMR-400 coax.
- Yours should be 84% so 15' 2 3/8".

Doing so should get you correctly tuned to the very possible 1.2:1 @ ch1 & ch40
& 1:1 on ch20.

 

[Rok55]

Thanks for the informative and precise answers, always seeking to learn more and understand the theory. More reading on SWR gave more insight for need of lower SWR and reduced reflection on the coax ground sleeve.

You should check tuning with the radials at 18' above ground and using an electrical 1/2 wave of coax..

Could you please explain the 18' above ground? The tech sheet from Maco states:
"The V58 can be tuned at 6 feet or so above the ground ............"

Please understand I am not questioning your expertise, I am only tying to understand the process.

Thanks ......... Rocky

 

[Needle Bender]

...Could you please explain the 18' above ground? The tech sheet from Maco states:
"The V58 can be tuned at 6 feet or so above the ground ............"

Please understand I am not questioning your expertise, I am only tying to understand the process.

Thanks ......... Rocky

I've found the tuning is most unaffected by good or bad ground at that height, and seems to change less when raised. (Usually antennas act electrically shorter as their elevation above ground is increased.)

Also, I've had the best luck tuning the Maco V58 when making the radiator 19' 8" (+/- 2") from the top of the matching network connector diagonal (where it meets the radiator) to the tip.
Plus, the wire usually ends up fairly close to the bolt, about 1/2-way around the ring. YMMV!

 

[w9cll]

Anything below 2 is fine.

 

[sp5it]

SWR is secondary, real question is: Where is resonance?
Mike

 

[Rok55]

SWR is secondary, real question is: Where is resonance?

Very much a newbie to the hobby and have no idea? I tried to do some research to establish a means of discovery and found none. Believe I have a basic understanding of the meaning of "resonance" but not a way to test for it. ??

 

[543_Dallas]

Can you tune a 5/8 wave antenna for resonance? I thought it was a non resonant antenna.

Without an swr analyzer the best you can do is tune the thing for lowest swr. As mentioned anything less than 2 is OK but you can do better. Unless you have a disability of some kind there's no reason to settle for a "good enough" match, that's lazy.

 

[sp5it]

Of course you can.
Mike

 

[Marconi]

Very much a newbie to the hobby and have no idea? I tried to do some research to establish a means of discovery and found none. Believe I have a basic understanding of the meaning of "resonance" but not a way to test for it. ??

Welcome to the forum Rok55.

Do a search at the top of the page on my computer. Type in "matching a Maco V58." You can leave all the other boxes blank. Click on "search." This will give you discussions on the subject back to 2010. This may give you some ideas. Then come back and ask questions.

 

[Big Kahuna]

SWR of 1.5 is completely usable for stock radio but you should be able to get that antenna to tune to a 1.2 to 1.3 across the band. I've set that antenna up multiple times and it usually didn't take much tweaking to get it lower.

 

[543_Dallas]

Of course you can.
Mike

Are you saying to tune for 0 reactance? I'm having a hard time reading between the lines when there's only one sentence.

 

[Marconi]

Can you tune a 5/8 wave antenna for resonance? I thought it was a non resonant antenna.

543, I think the reference you are referring to suggest a 5/8 wavelength antenna is not a resonant length. Of course a matching device should be able to adjust the impedance at or near resonance.

 

[543_Dallas]

543, I think the reference you are referring to suggest a 5/8 wavelength antenna is not a resonant length. Of course a matching device should be able to adjust the impedance at or near resonance.

Right. So to do that are were shooting for 50 ohms and the reactance to be as low as possible?