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Which coax is better?
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tub...@myshop.com
Mar 15, 2019, 4:24:00 AM3/15/19
to
I never remember the numbers, so i will just describe it.
CB and low power ham radios use one type.
TV antennas use the other.
Both coax is about the same diameter and looks alike on the outside.
I have a police scanner. It has an ext. antenna connector on the rear
that is one of those "Motorola jacks" (same as the ant. connectors on
car radios).
I used to use a CB (car type) antenna on my roof, for the scanner. It
used the CB coax with them big connectors on the end. When I moved, that
antenna got left behind.
I recently dug out that scanner again, and have it connected to my
homemade weather radio outside antenna. But this weather antenna has the
TV style coax with F connectors.
I dont yet have an adaptor for F connector to the Motorola jack, but
found one on ebay and am waiting for it to arrive.
My question is whether it matters which coax is used? My weather radio
works fine as it is. I did try the scanner using alligator clips to
connect the antenna and i do get a signal.
I dont know how well that antenna, made specifically for 162.xx mhz will
work on the UHF scanner bands, but I have gotten 155.xx VHF signals
well, even with the alligator clip mess.....
CB and low power ham radios use one type.
TV antennas use the other.
Both coax is about the same diameter and looks alike on the outside.
I have a police scanner. It has an ext. antenna connector on the rear
that is one of those "Motorola jacks" (same as the ant. connectors on
car radios).
I used to use a CB (car type) antenna on my roof, for the scanner. It
used the CB coax with them big connectors on the end. When I moved, that
antenna got left behind.
I recently dug out that scanner again, and have it connected to my
homemade weather radio outside antenna. But this weather antenna has the
TV style coax with F connectors.
I dont yet have an adaptor for F connector to the Motorola jack, but
found one on ebay and am waiting for it to arrive.
My question is whether it matters which coax is used? My weather radio
works fine as it is. I did try the scanner using alligator clips to
connect the antenna and i do get a signal.
I dont know how well that antenna, made specifically for 162.xx mhz will
work on the UHF scanner bands, but I have gotten 155.xx VHF signals
well, even with the alligator clip mess.....
tabb...@gmail.com
Mar 15, 2019, 4:39:36 AM3/15/19
to
NT
Look165
Mar 15, 2019, 5:43:56 AM3/15/19
to
The cable must match the impedances at both ends and these impedances
must be the same.
Personally, I recommend shielded cable (signal+alu shield+ground return).
must be the same.
Personally, I recommend shielded cable (signal+alu shield+ground return).
Fox's Mercantile
Mar 15, 2019, 9:11:36 AM3/15/19
to
On 3/15/19 3:23 AM, tub...@myshop.com wrote:
> I never remember the numbers, so i will just describe it.
>
> CB and low power ham radios use one type.
> TV antennas use the other.
Communication radios tend to use 50 ohm coax.
> I never remember the numbers, so i will just describe it.
>
> CB and low power ham radios use one type.
> TV antennas use the other.
RG-58 1/4", RG-8X 5/16" and RG-8 RG-213 1/2" (Roughly)
TV and most CCTV stuff use 75 ohm coax.
RG-59 and RG-6 5/16" and RG-11 1/2"
> Both coax is about the same diameter and looks alike on the outside.
> I have a police scanner. It has an ext. antenna connector on the rear
> that is one of those "Motorola jacks" (same as the ant. connectors on
> car radios).
>
> My question is whether it matters which coax is used?
It doesn't make much if any difference.
Don't let people wind you up about impedance matching on receive
antennas.
> I dont know how well that antenna, made specifically for 162.xx mhz will
> work on the UHF scanner bands
1/4 wave whip antenna (16-18")on VHF will look like 3/4 wave on
UHF. And will work just fine.
--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com
Ralph Mowery
Mar 15, 2019, 10:17:48 AM3/15/19
to
In article <p56dncFkePkdORbB...@giganews.com>,
jda...@att.net says...
impedance varies all over the place over a wide range of frequencies.
Just as Jeff says.
I would use the RG-6 TV type as the losses are usually lower for coax
around 1/4 inch in diameter and the cost is very low. Some have even
gotten short ( 50 to 100 feet) pieces for free from the cable TV
companies. The main problem will be getting a good connection. You
need the proper crimp connectors and tool as the shield is aluminum.
For me, the next best would be some RG-8X. It is 50 ohm, but the shield
and center conductor is copper so you can solder to it with no problem.
The rg-8X is about the same size as the rg-6 TV coax. Uhnless the
distance is less than about 25 feet I would stay away from the rg-58
that is slightly smaller in diameter.
jda...@att.net says...
>
> > I have a police scanner. It has an ext. antenna connector on the rear
> > that is one of those "Motorola jacks" (same as the ant. connectors on
> > car radios).
> >
> > My question is whether it matters which coax is used?
>
> It doesn't make much if any difference.
> Don't let people wind you up about impedance matching on receive
> antennas.
>
>
For receiving the impedance will not make any difference as the receiver
> > I have a police scanner. It has an ext. antenna connector on the rear
> > that is one of those "Motorola jacks" (same as the ant. connectors on
> > car radios).
> >
> > My question is whether it matters which coax is used?
>
> It doesn't make much if any difference.
> Don't let people wind you up about impedance matching on receive
> antennas.
>
>
impedance varies all over the place over a wide range of frequencies.
Just as Jeff says.
I would use the RG-6 TV type as the losses are usually lower for coax
around 1/4 inch in diameter and the cost is very low. Some have even
gotten short ( 50 to 100 feet) pieces for free from the cable TV
companies. The main problem will be getting a good connection. You
need the proper crimp connectors and tool as the shield is aluminum.
For me, the next best would be some RG-8X. It is 50 ohm, but the shield
and center conductor is copper so you can solder to it with no problem.
The rg-8X is about the same size as the rg-6 TV coax. Uhnless the
distance is less than about 25 feet I would stay away from the rg-58
that is slightly smaller in diameter.
Jeff Liebermann
Mar 15, 2019, 12:37:20 PM3/15/19
to
On Fri, 15 Mar 2019 03:23:53 -0500, tub...@myshop.com wrote:
>CB and low power ham radios use one type.
RG-58c/u
>CB and low power ham radios use one type.
>TV antennas use the other.
RG-59a/u (which is garbage)
>Both coax is about the same diameter and looks alike on the outside.
ohms. I also have a fair collection of Type-F to BNC or PL-259.
The mismatch loss is negligible:
<https://www.qsl.net/n9zia/wireless/75_ohm_hardline.html>
Please note that there are variations in RG-6/u quality varying from
Radio Shack junk to "satellite TV" grade with lower losses at >1GHz
frequencies. Some variations are more flexible than others, some have
a UV resistant jacket, and some use CCA (copper clad alumunium) which
is cheap junk. Caveat emptor.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
tabb...@gmail.com
Mar 15, 2019, 12:47:21 PM3/15/19
to
On Friday, 15 March 2019 13:11:36 UTC, Fox's Mercantile wrote:
> On 3/15/19 3:23 AM, tub...@myshop.com wrote:
> > I never remember the numbers, so i will just describe it.
> >
> > CB and low power ham radios use one type.
> > TV antennas use the other.
>
> Communication radios tend to use 50 ohm coax.
> RG-58 1/4", RG-8X 5/16" and RG-8 RG-213 1/2" (Roughly)
>
> TV and most CCTV stuff use 75 ohm coax.
> RG-59 and RG-6 5/16" and RG-11 1/2"
>
> > Both coax is about the same diameter and looks alike on the outside.
>
> The 75 ohm is noticeably thicker.
>
> > I have a police scanner. It has an ext. antenna connector on the rear
> > that is one of those "Motorola jacks" (same as the ant. connectors on
> > car radios).
> >
> > My question is whether it matters which coax is used?
>
> It doesn't make much if any difference.
> Don't let people wind you up about impedance matching on receive
> antennas.
Co-ax impedance is not critical, but choosing rf rather than baseband co-ax is.
> On 3/15/19 3:23 AM, tub...@myshop.com wrote:
> > I never remember the numbers, so i will just describe it.
> >
> > CB and low power ham radios use one type.
> > TV antennas use the other.
>
> Communication radios tend to use 50 ohm coax.
> RG-58 1/4", RG-8X 5/16" and RG-8 RG-213 1/2" (Roughly)
>
> TV and most CCTV stuff use 75 ohm coax.
> RG-59 and RG-6 5/16" and RG-11 1/2"
>
> > Both coax is about the same diameter and looks alike on the outside.
>
> The 75 ohm is noticeably thicker.
>
> > I have a police scanner. It has an ext. antenna connector on the rear
> > that is one of those "Motorola jacks" (same as the ant. connectors on
> > car radios).
> >
> > My question is whether it matters which coax is used?
>
> It doesn't make much if any difference.
> Don't let people wind you up about impedance matching on receive
> antennas.
> > I dont know how well that antenna, made specifically for 162.xx mhz will
> > work on the UHF scanner bands
>
> Generally, UHF is 3 times the VHF frequencies. What looks like a
> 1/4 wave whip antenna (16-18")on VHF will look like 3/4 wave on
> UHF. And will work just fine.
NT
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