I hate tuning CB antennas

[mmckenna]

@mmckenna, so I discovered. It looks like a far better method for building an antenna system. It also looks like it is capable of a lot more than just tuning antennas. I'm kind of excited to see what it can do and what I can learn through it.

Thanks again.

Smittie.

I've got an $18,000 version of that at work. The work one is nice, and I can bring it home if needed. For quick/dirty use, the NanoVNA's are hard to beat. The small screen size and clunky interface is its shortfall, however, compared to an SWR meter, it gives you way more information.

I do still carry a directional wattmeter (SWR meter) in my work truck, as well as one in my garage, and they have their uses, but they don't get used quite so often any more. You can really do a lot with those NanoVNA's.

Seems like everyone and their stupid brother decided to make a "how-to" NanoVNA video. There's some real crap on the YouTubes.

 

[slowmover]

I've got an $18,000 version of that at work. The work one is nice, and I can bring it home if needed. For quick/dirty use, the NanoVNA's are hard to beat. The small screen size and clunky interface is its shortfall, however, compared to an SWR meter, it gives you way more information.

I do still carry a directional wattmeter (SWR meter) in my work truck, as well as one in my garage, and they have their uses, but they don't get used quite so often any more. You can really do a lot with those NanoVNA's.

Seems like everyone and their stupid brother decided to make a "how-to" NanoVNA video. There's some real crap on the YouTubes.

It’s going to help anyone to also learn what is being measured, and how.

IOW, the theoretical underpinnings.

NanoVNA makes it much easier to demonstrate to one’s self those statements and their parameters with an ARRL overview.

Antennas are big boy stuff.

.

 

[smittie]

NanoVNA makes it much easier to demonstrate to one’s self those statements and their parameters with an ARRL overview.

THIS is the part I am most excited about. The frustrating part of trying to tune an antenna system using only an SWR meter is that the system is a blackbox. When you only have one point of measurement (VSWR) and a lot of contributing components, it is really difficult to get one's head around the interaction of those components. Having a tool that provides much broader feedback in realtime as the various components are manipulated makes it a LOT easier to begin to grasp the interactions. I might even fire up the Galaxy 959 and try playing with SSB.

Yes, I have the ARRL HAM License Manual. Theory is interesting but practical, observable application is invaluable.

I really appreciate the experience, patience and knowledge here. Thank you for contributing to my education.

Gratefully,
Smittie

 

[mmckenna]

This isn't from a NanoVNA, this is from an expensive commercial model. But it shows you how easy it is to find the point of resonance (low SWR) for the antenna.

This was years ago when I still had a CB mounted in my old truck. Larsen NMO-27 mounted center of the roof. Nice low SWR in the center:

 

[mmckenna]

Here's a zoomed out version looking at everything from 26MHz to 28MHz, easier to see the low SWR dip in the center of the CB band:




Nano VNA will show you the same thing, just a bit less resolution.

 

[smittie]

This was the video that convinced me to pull the trigger and buy a nanoVNA. It also reignited my curiosity about SSB.

Respectfully,
Smittie

 

[slowmover]

The video is more in the line of persuasion (as you indicate) than a How To in re the device.

— The worthiness of accurate tuning pays off in multiple ways, IOW.

Short, and gets across main point with examples.

Here’s a vid I earlier linked in re using a NanoVNA to quantify manual tuner set-up (as that device sets last bit for big truck mobile successfully):

Point is: NanoVNA a useful tool to own.

.

 

[smittie]

@slowmover, the video I posted showed me exactly how to do, including all the steps, exactly what I have been struggling to get done well. Other videos indicated that the VNA can also help me understand other aspects of RF and antenna systems.

 

[slowmover]

@slowmover, the video I posted showed me exactly how to do, including all the steps, exactly what I have been struggling to get done well. Other videos indicated that the VNA can also help me understand other aspects of RF and antenna systems.

Okay. I watched it before posting that.

There are other vids which go into more detail on its use.

One can get pretty far back into the weeds re antenna tuning. Tail-chasing. I agree that tool sophistication is how to avoid most of that, and that the video is persuasive in that aspect.

.

 

[smittie]

Point is: NanoVNA a useful tool to own.

Yes. I don't have mine yet but from what I've learned thus far, I wish I had this instead of an SWR meter. I understand that SWR meters have their own value but for what I want to accomplish, the NanoVNA is a far more useful tool.

Respectfully,
Smittie

 

[smittie]

Ordered the Larsen NMO30, two 64" whips, and the appropriate spring. Using the NanoVNA I plan to tune it first without the spring, get a snapshot of the curve and then retune with the spring in place in order to compare the difference. The assumption is that the coils of the spring broaden the bandwidth, or so I've been told.

 

[K6GBW]

Please make sure to post your results. I'm sure we'd all be interested in what you find.

 

[smittie]

Please make sure to post your results. I'm sure we'd all be interested in what you find.

Wilco.

 

[smittie]

Got an antenna working and was finally able to get a radio check with a driver about 4 miles away.
The Cobra 25 has a "Dyna Mike" knob and I currently have an Astatic mic on the radio. The responder had a hard time understanding me until I turned the Dyna Mic all the way up.
Is there a proper use of this gadget?
Is the Astatic a decent mic or should I go back to stock?

The edumacation continues.

 

[smittie]

So, I bought the Larsen NMO30 and the 64" whip. Got it tuned to 1.1 SWR using the NanoVNA and verified using an SWR meter. And then the center tab broke off.
All done with Larsen. Back to Laird products.

 

[K6GBW]

Wow, I'm really surprised by that. I've had great luck with Larsen in the past. Any chance it's a manufacturers defect? I'm wondering if it's replaceable under warranty.

 

[smittie]

I have two Larsen antennas and they both use the bent metal tab for the center contact. Laird, Tram and Browning (Tram/Browning) use a spring loaded brass/copper plunger for the center contact. Better construction.
I am going to contact Antenna Farm and talk to them about it. I would prefer a refund or store credit to a replacement. I just not very impressed with Larsen quality.

 

[K6GBW]

I get it. Getting burned leaves a bad after taste. Laird used to make a CB27 antenna. I'm not sure if it's still made but they're probably still available online somewhere. Where did you end up mounting it?

 

[smittie]

I get it. Getting burned leaves a bad after taste. Laird used to make a CB27 antenna. I'm not sure if it's still made but they're probably still available online somewhere. Where did you end up mounting it?

The CB27 is still made. I have a couple of them.
Mounted it use the Rugged Ridge bracket but that seems to be a problem. The Lairds show very poorly (1.8 SWR) on that mount and I think it is because the CB27 requires a DC ground and the Rugged Ridge mount against the plastic body parts probably does not provide enough through the single bolt.
I am considering moving the CB antenna to the steel bumper. The VHF/UHF antenna appears to be fine on the Rugged Ridge bracket.

Comments, suggestions and criticisms welcome.

 

[prcguy]

I've got an $18,000 version of that at work. The work one is nice, and I can bring it home if needed. For quick/dirty use, the NanoVNA's are hard to beat. The small screen size and clunky interface is its shortfall, however, compared to an SWR meter, it gives you way more information.

I do still carry a directional wattmeter (SWR meter) in my work truck, as well as one in my garage, and they have their uses, but they don't get used quite so often any more. You can really do a lot with those NanoVNA's.

Seems like everyone and their stupid brother decided to make a "how-to" NanoVNA video. There's some real crap on the YouTubes.

So, you got a wee little one at work. When I go on consulting jobs I'm handed a 32GHz Agilent Field Fox with all options that runs north of $100k. I've used it to measure and tweak my CB and hamster antennas which is a little silly but it sure gets the job done. Problem with using this level of equipment is it costs hundreds of $$ in adapters to get down to PL-259s.