Using F-Connectors with 50 Ohm RG8

[ZaqHydN]

Using F-Connectors (Typical CATV connectors) with RG8/RG58 (50 ohm) Antenna Cable for RF Transmission.

I am installing a Thru-Wall Antenna Port in my apartment (with permission) for my Ham Rig.

I do not want to install a PL/SO connector type at the wall plate because they are large and uncommon.

I would rather install an F-Type Wall-Jack because they are smaller and when I move out, there isn't an odd-looking connector left behind.


F connectors are also much smaller and would make for a much cleaner installation as I plan on using a right-angle adaptor so the RF Line isn't sticking out from the wall.

Naturally, I would be making a custom cable that goes to the radio (PL/SO) to the F-type wall-jack.

The exterior connector will come from inside to an Exterior F-Block (easily grounded):



The exterior would also be using the same type of custom cable (F to PL/SO) to get from the insertion point to the antenna.

I know CATV coax (typical RG6/x) is 75ohm, but I will be using 50ohm RG8/x. Only the connectors for the Thru-Wall Setup would be the CATV type.

Knowing that every "connector/adaptor/jumper" inserted in a TX/RX line acts as a BalUn to some degree, I am curious as to what effects using F-Connectors would have in 50ohm TX/RX performance.

I have not heard of anyone using F-Connectors with Amateur Radio. I have also searched for information on this with no application-specific results. I only find information about coax and connectors, but not information about the actual application of using F Connectors in an 50ohm TX/RX Line.

My topic questions are:

A. Can the F-Connectors be used with a 50ohm system without a significant impact on TX/RX performance?

B. If you have had experience with using F-Connectors in an RF Transmission Line, what was the effect on your SWR/Power ratios?

Experimentally yours, N3LOY.
|----/-|

 

[ka3aaa]

i've never seen or heard of any amateur radio equipment with "f" connectors on them or use them to tx.

i think your just asking for trouble and i wouldn't use them.

as small as rg8x is i would drill a 5/16 inch hole thru the wall somewhere and have no connector other than where the coax meets the antenna and or radio.

just my two cents for what its worth.

 

[mmckenna]

While not ideal, F connectors and 75Ω will work. Yes, there is an SWR hit, but it's not going to damage your equipment as long as you pay attention and test it before transmitting. I'd pay close attention to your transmit power, as these consumer grade things usually are not designed for much.

A couple of ideas that you may want to research:

Use a BNC connector instead of an F connector. It's similar size and could be swapped out with an F connector if you move.

Use RG-11, it's sort of close to RG-8 in size and you can easily get F connectors for that.

Or, like ka3aaa said, just use a smaller cable and feed it through the hole direct to your radio and skip all the adapters. Unless you have a long run, RG-8 may not be much help. You could also look at cables like LMR-240, etc.

 

[Blackswan73]

RG-58 to f
B.S.

USA-CA RG58 PL259 UHF MALE to F MALE Coaxial RF Pigtail Cable | eBay

Connector 1: PL259 UHF MALE. Cable Type: RG58. Connector 2: F MALE. Center conductor: Stranded Copper.

www.ebay.com

 

[WA8ZTZ]

Use RG6 with the F connectors and you will be fine. Been doing it here for years.
You probably will not even notice the slight SWR mismatch. F connectors will easily handle 100 watts,
although buy name brand connectors rather than what you might find at the dollar store.
You will need some sort of adapter at the SO-239 on the rig.

 

[prcguy]

An F connector will handle a lot more than 100w and easily 1kW at HF. That doesn't mean you should use them. If you already have a 50 ohm system why not get a blank wall plate and install a BNC barrel connector? Same basic size as an F connector and they make BNC connectors for RG-8.

 

[ZaqHydN]

Great responses, this topic lacked any quantifiable research by actual people who have experience with this type of Line use.

Just to reiterate, I intended to use 50ohm coax (not the 75ohm coax) with only the terminators that facilitate the Thru-Wall insertion being the F-type. I don't imagine the connectors would have a significant impact on the total impedance.

I made a decision today to save money and time as I don't plan to live at this apartment through the end of this year, to simply do a straight Thru-Wall line insertion and just terminate the coax with a typical PL connector. The hole in the wall is insignificant and I can easily remove the installation and cover the hole with a dollar wall plate on my way out.

Today I erected the antenna and hopefully it's not too stressful on the Satellite Antenna Arm (the satellite antenna was removed). I have a shorter/lighter antenna in shipment if I feel my 9-footer puts too much stress on the arm, it's getting replaced with a Quad-Band Mobile antenna in the future if I get my new 4-band radio before I move.

Time to heat up the soldering iron!

 

[Blackswan73]

The RG 58 cable I linked to is 50 ohm. You are correct though a small hole should present no problems. Good luck with your installation.

B.S.

 

[AC9KH]

i've never seen or heard of any amateur radio equipment with "f" connectors on them or use them to tx.

I've used RG-6 with F-connectors for years on HF wire antennas, run 1200 watts thru them with no problem at all.

Using F-Connectors (Typical CATV connectors) with RG8/RG58 (50 ohm) Antenna Cable for RF Transmission.

A. Can the F-Connectors be used with a 50ohm system without a significant impact on TX/RX performance?

Yes, it will work fine. In fact, instead of using RG-8 from the wall jack you can run RG-6 and just use a F female to PL-259 male adapter to hook it up. Port A on the right switch in the photo has one of those on it, and that antenna runs 1,200 watts on it. Port A on the left switch has RG-6 terminated with a PL-259, and that one goes to a vertical ground plane antenna. The trouble with putting a PL-259 on RG-6 is that the shield on RG-6 is aluminum and can't solder to it. So the F to PL-259 adapter works better.

The only thing I would caution with F-connectors is to use the screw-on style on RG-6. The crimp style can crush the dielectric and while that won't cause a problem on TV or satellite, if you put power to it it can arc thru from the center conductor to the shield where the dielectric gets damaged from the crimp.

 

[GregOH]

The RG 58 cable I linked to is 50 ohm. You are correct though a small hole should present no problems. Good luck with your installation.

B.S.

So since 50 ohm RG-58 with an F type end can be purchased, couldn't he just buy a spool of RG-58 and crimp on or twist on connectors and make his own at whatever length desired?

I thought the center conductor of RG-58 is smaller in diameter than that of RG6, so would it be a good connection with a wall plate connector or a barrel that normally accepts RG6 cable?

 

[buddrousa]

@ZaqHydN
Dear Newbie more than 1 person that posted replays back to you work in the RF Industry and are very knowledgeable about RF connectors and there uses.

 

[merlin]

I thought the center conductor of RG-58 is smaller in diameter than that of RG6

RG 58 U has a solid center conductor like RG 6. The 58 is a different size from the normal F connectors, but F connectors for RG58 U do exist.
Save a couple of bucks with RG 6 with F connectors, as mentioned it works fine for HF amateur and will handle a full gallon.

 

[GregOH]

RG 58 U has a solid center conductor like RG 6. The 58 is a different size from the normal F connectors, but F connectors for RG58 U do exist.
Save a couple of bucks with RG 6 with F connectors, as mentioned it works fine for HF amateur and will handle a full gallon.

I'm using RG 6 now. I was just questioning the use of an F type connector with RG 58. Thanks for the reply.

 

[k6cpo]

Wouldn't it be easier to use some kind of a window feed-thru and eliminate all this guessing about cable and connectors? Something like this perhaps:

 

[W4AXW]

as small as rg8x is i would drill a 5/16 inch hole thru the wall somewhere and have no connector other than where the coax meets the antenna and or radio.

Completely agree. Have done that very thing with 8x.

Seems like too much hoop-jumping just to leave a smaller hole in an easily replaceable plastic outlet cover. But that's me..........

7 3

 

[kb1fua]

I've never used F connectors with any of my amateur equipment.
However, mini uhf connectors are similar in size, and they are meant to be used on 50 ohm coax. This might be another option for you. Some Motorola equipment have used them in the past.

 

[exkalibur]

I've used off the shelf RG-6 cables and F connectors for receive purposes in the past and have never had a problem. I haven't tried for TX, but I can't imagine there would be much of a problem either.

 

[ArloG]

Surprised there's no mention of 50 ohm F connectors. Yes, there is such an animal.

 

[Blackswan73]

Check post 12

B.S.

 

[G7RUX]

Great responses, this topic lacked any quantifiable research by actual people who have experience with this type of Line use.

Just to reiterate, I intended to use 50ohm coax (not the 75ohm coax) with only the terminators that facilitate the Thru-Wall insertion being the F-type. I don't imagine the connectors would have a significant impact on the total impedance.

I made a decision today to save money and time as I don't plan to live at this apartment through the end of this year, to simply do a straight Thru-Wall line insertion and just terminate the coax with a typical PL connector. The hole in the wall is insignificant and I can easily remove the installation and cover the hole with a dollar wall plate on my way out.

Today I erected the antenna and hopefully it's not too stressful on the Satellite Antenna Arm (the satellite antenna was removed). I have a shorter/lighter antenna in shipment if I feel my 9-footer puts too much stress on the arm, it's getting replaced with a Quad-Band Mobile antenna in the future if I get my new 4-band radio before I move.

Time to heat up the soldering iron!

I have done precisely this on a “covert” installation in an apartment block and you are correct in that the F connector will work just fine. You will likely need to make up some tails to connect to the F bulkhead since the centre core of the RG8 won’t fit directly.
The impedance mismatch will be measurable with the right kit but definitely won’t be either an issue or noticeable for your use.
Incidentally, I have also made a VHF installation using 75 ohm coax and it worked perfectly well with only a small mismatch.