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Old June 6th 10, 02:19 AM posted to rec.radio.amateur.antenna
Geoffrey S. Mendelson[_2_] Geoffrey S. Mendelson[_2_] is offline
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Default BNC connectors 75 Ohm versus 50 Ohm?

Jeff Liebermann wrote:

Hopefully, it was a "push-on" tool and connector
http://www.arrisistore.com/digicon/Digicon-F-Connector-Installation-Guide.pdf
not the piece of junk with the small crimped ring.


Thanks,

Yes, but mine looks more like a nut cracker, however it works the same
way.

Be thankful. I find them to be a necessary evil as most ham radios
require them. Meanwhile, commercial radios are moving away from UHF
and toward other connectors, such as Type-N, BNC, TNC, Mini-UHF, and
SMA. However, Comerica base antennas remain UHF or Type-N.


Me too. Since all of the ham radios I have were either brought from the
US in 1996 when I moved here, or even older ones brought here, they use
Pl-259's or in one case an RCA jack (Drake SP-R4) for the antenna.

TV sets still use the Belling-Lee plugs (called PAL connectors in the US)
and so do VCRs. Everything else uses F connectors (cable TV, Satellite TV)
although RF outputs to TV sets have gone the way of the VCR.

DVB is just starting here and the tuners use Belling-Lee connectors. F
to Belling-Lee adaptors are common here, and even in the US, where Radio
Shack sells them.


That's what I do. Most of my cables are NOT terminated with UHF
connectors. If I need to go to UHF, I use an adapter.


They are also hard to get and expensive.


Yes, they work. I use quite a bit of RG-6a/u and prefer to have
everything terminated by the same connector, which is the CATV
standard F connector. If I need BNC, I use an adapter.


OK, So where do you get your adaptors?


Agreed. The good ones are "push on" F connectors.


I gave up about 10 years ago and used the cheap screw on ones because they
gave me a better fit than the crimp "around" types. The push on ones
are a lot better.



There are such things as real 75 ohm BNC plugs and jacks. They're
easy to recognize because they lack the PTFE dielectric. The 75 ohm
connectors will mate properly with the 50 ohm connectors. There is
little risk of VSWR problems from using 50 ohm connectors on RG-6a/u.


ok.

http://www.qsl.net/n9zia/wireless/75_ohm_hardline.html
Basically, any small loss from VSWR is compensated by the lower loss
per meter of RG-6a/u as compared to RG-58a/u. Methinks you're safe
using all 50 ohm connectors.[1]


Good, thanks.

[1] I just counted 7 assorted coaxial cables going between my roof and
various RF devices in my house. All but one are 75 ohm RG-6a/u. Some
are double shielded, while others are quad shielded. The connectors
are slightly different. All the HF and VHF/UHF antennas use 75 ohm
coax. The one 50 ohm LMR-400 run is for the 900MHz antenna.


That's not an issue, 900mHz is not a ham band here, and 1.gHz too short
range to consider using. I think there is one 1.2gHz repeater in the country,
and I can't hit the co-located 2m repeater anyway.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge or
understanding, as in he has a sub-wikipedia understanding of the situation.
i.e possessing less facts or information than can be found in the Wikipedia.