Electronics > RF, Microwave, Ham Radio

CB and Ham Radio Techs Love Their Bird Wattmeters

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joeqsmith:
Looking at Amphenol's site:
https://www.amphenolrf.com/rf-connectors/uhf-connectors.html

Impedance Non-Constant
Frequency Range DC - 300 MHz (DC - 1 GHz on Extended Range Designs)

They do not explain the GHz extended range designs.  Looking on Digikey, they claim several are good well above 1GHz.   I wonder home my crap adapters I bought for the Watt meter would compare with a decent N. 

vk6zgo:
My ancient Icom IC490 (circa mid 1980s) has an N connector, but my early 2000s IC400, which was sold for use on business bands around 400-500MHz, & also for the Australian UHF CB band, depending upon its programming (It can also be programmed for the Amateur "70cm" band, as mine is) comes, as standard, with a SO-239 on the back.

It seems Icom have given up trying to educate not only hams, but all those business users as well.

xrunner:

--- Quote from: joeqsmith on September 26, 2023, 11:32:30 pm ---Looking at Amphenol's site:
https://www.amphenolrf.com/rf-connectors/uhf-connectors.html

Impedance Non-Constant
Frequency Range DC - 300 MHz (DC - 1 GHz on Extended Range Designs)

They do not explain the GHz extended range designs.  Looking on Digikey, they claim several are good well above 1GHz.   I wonder home my crap adapters I bought for the Watt meter would compare with a decent N.

--- End quote ---

I looked at that link ... is that the datasheet per se? I didn't find a more detailed one listed there. One that perhaps had some graphs to gaze upon.  :(

I'll try to find an actual datasheet on the PL-259 later, I mean there must be one with actual plots out there somewhere. I've never tried to find one.

 :-DD

The ham manufacturers could have settled on using N connectors on UHF and above back in the day and stuck with it. By now the hams would have learnt to use them. But alas they didn't, and now the PL-259 / SO-239 is so entrenched it wouldn't do any good to start. Most hams will not make up a new cable with an N male connector for a radio that has the N female. All they will do is grab an adapter and screw it on - F*ck it, problem solved. So what purpose did manufacturing the radio with an N connector actually achieve?  :-//

vk6zgo:

--- Quote from: joeqsmith on September 26, 2023, 11:32:30 pm ---Looking at Amphenol's site:
https://www.amphenolrf.com/rf-connectors/uhf-connectors.html

Impedance Non-Constant
Frequency Range DC - 300 MHz (DC - 1 GHz on Extended Range Designs)

They do not explain the GHz extended range designs.  Looking on Digikey, they claim several are good well above 1GHz.   I wonder home my crap adapters I bought for the Watt meter would compare with a decent N.

--- End quote ---

I have seen some strange looking SO-239s over the years with the insulation having an "air gap" in it, maybe those are what they are referring to.
The business end of all the PL259s I've seen look the same, though, no matter which type, so I can't see how just modifying the socket would work.

joeqsmith:
The ones that are in that cheap RS-70 Watt meter that doesn't work has a semi sort of air line.   

I used some lowish end N adapters I have and tried to compare them with the two N to UHF adapters using the LiteVNA.   Started out calibrating the VNA from 50k - 8G.  I then took a baseline measurement.

Next an SMA male to N male, N female barrel,  N male SMA female was inserted. 

Last, the N female barrel was replaced with the two N to UHF adapters which were connected with an Amphenol UHF female barrel.   

We can see from the TDR plot, the impedance of that UHF mess is very unstable and reaches about 27 ohms.  FWHH is about 30mm, which oddly enough is about the length of that UHF mess. 

If I plot S21, at 500MHz the loss with the UHF mess is about 0.4dB.   

Conclusion, UHF connectors make a poor mans Betty standard :-DD

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