Pages: [1]   Go Down

Author Topic: RG-8X As Jumpers  (Read 619 times)

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
RG-8X As Jumpers
« on: November 07, 2020, 06:38:33 PM »

I am in the process of moving some equipment around in the house to a new shack location.

I have always used thinner coax (RG-8X) for the short jumpers between radios, antenna switches, meters and tuners before due to flexiblity.

I wouldn't think that the 3-4' per radio before the switch which has 400Max to the antenna would have any significant loss avove the 400Max.

What are the thoughts?

Also I've been looking at the sequence of equipment and began to wonder in what order after the radio should they occur, and at which point to measure the SWR with my VNA.

I normally tune the antenna traps with VNA attached to a 6' piece of coax to the choke at the antenna.

So many thoughts backed up due to the election drama that now are coming out
 ;D ::)
Logged
So Many Toys.......So Little Time!

K1FBI

  • Member
  • Posts: 1475
Re: RG-8X As Jumpers
« Reply #1 on: November 07, 2020, 07:16:11 PM »

I am in the process of moving some equipment around in the house to a new shack location.

I have always used thinner coax (RG-8X) for the short jumpers between radios, antenna switches, meters and tuners before due to flexiblity.

I wouldn't think that the 3-4' per radio before the switch which has 400Max to the antenna would have any significant loss avove the 400Max.

What are the thoughts?

Also I've been looking at the sequence of equipment and began to wonder in what order after the radio should they occur, and at which point to measure the SWR with my VNA.

I normally tune the antenna traps with VNA attached to a 6' piece of coax to the choke at the antenna.

So many thoughts backed up due to the election drama that now are coming out
 ;D ::)
It depends on your frequency of operation.
4 feet of RG-8X on UHF will turn your 100 watts into 93 watts.
The same jumper on 20 meters would only cost you 1 watt.
Logged

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: RG-8X As Jumpers
« Reply #2 on: November 07, 2020, 07:45:29 PM »

I am in the process of moving some equipment around in the house to a new shack location.

I have always used thinner coax (RG-8X) for the short jumpers between radios, antenna switches, meters and tuners before due to flexiblity.

I wouldn't think that the 3-4' per radio before the switch which has 400Max to the antenna would have any significant loss avove the 400Max.

What are the thoughts?

Also I've been looking at the sequence of equipment and began to wonder in what order after the radio should they occur, and at which point to measure the SWR with my VNA.

I normally tune the antenna traps with VNA attached to a 6' piece of coax to the choke at the antenna.

So many thoughts backed up due to the election drama that now are coming out
 ;D ::)
It depends on your frequency of operation.
4 feet of RG-8X on UHF will turn your 100 watts into 93 watts.
The same jumper on 20 meters would only cost you 1 watt.

10M- 80M only
Logged
So Many Toys.......So Little Time!

K1FBI

  • Member
  • Posts: 1475
Re: RG-8X As Jumpers
« Reply #3 on: November 07, 2020, 07:56:14 PM »

1.5 watts loss on 10 meters and 1/2 watt loss on 80 meters for a 4 foot jumper.
No one on the other end will ever notice.
Get on the air and enjoy your station...
Logged

W9IQ

  • Member
  • Posts: 8866
Re: RG-8X As Jumpers
« Reply #4 on: November 08, 2020, 05:25:21 AM »

For 100 watt HF, the RG-8X will be fine. If you are running QRO or high SWR50, some additional scrutiny is warranted.

- Glenn W9IQ
« Last Edit: November 08, 2020, 05:43:15 AM by W9IQ »
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: RG-8X As Jumpers
« Reply #5 on: November 08, 2020, 06:15:38 AM »

One of the major concerns was the coax/antenna switch connections. I have a rotary B&W that uses a lot less space with smaller diameter cable due to the bend radius’.

I only run barefoot, and have no future plans on any
higher power.

Now let’s address the sequence of equipment and SWR reading  location.
Logged
So Many Toys.......So Little Time!

W9IQ

  • Member
  • Posts: 8866
Re: RG-8X As Jumpers
« Reply #6 on: November 08, 2020, 06:49:45 AM »

Now let’s address the sbinequence of equipment and SWR reading  location.

You will generally want to place your SWR meter between the transceiver and the antenna tuner. If you have an SWR meter in the antenna tuner, then you could locate your external meter after the antenna tuner to watch for any changing SWR conditions with your antenna system. That assumes the meter works over the SWR range of the antenna system.

If you have no external antenna tuner, then place the meter between the transceiver and the antenna switch.

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: RG-8X As Jumpers
« Reply #7 on: November 08, 2020, 12:34:50 PM »

Now let’s address the sbinequence of equipment and SWR reading  location.

You will generally want to place your SWR meter between the transceiver and the antenna tuner. If you have an SWR meter in the antenna tuner, then you could locate your external meter after the antenna tuner to watch for any changing SWR conditions with your antenna system. That assumes the meter works over the SWR range of the antenna system.

If you have no external antenna tuner, then place the meter between the transceiver and the antenna switch.

- Glenn W9IQ

I have 4 radios that are "reverse fed" into my antenna switch so I can feed to one antenna.

Typical Set Up:

     TS-820s - AT-820 Manual Tuner - SWR Meter - Antenna Switch Pos #1

I would think that since I am now feeding 4 radios to one antenna via the
switch that I should put the SWR meter between the switch and the antenna
so as to pick up each radio sequence when used.

Correct?
Logged
So Many Toys.......So Little Time!

W9IQ

  • Member
  • Posts: 8866
Re: RG-8X As Jumpers
« Reply #8 on: November 08, 2020, 01:24:13 PM »

That is correct.

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

NK5G

  • Member
  • Posts: 113
Re: RG-8X As Jumpers
« Reply #9 on: November 12, 2020, 12:05:08 PM »

I have use 8X for jumpers for QRO for a long time and they work just fine. Any losses on HF are a minuscule percentage. 8X is much easier to work with as jumpers as opposed to LMR400.
Logged

N9LCD

  • Member
  • Posts: 260
Re: RG-8X As Jumpers
« Reply #10 on: November 14, 2020, 05:50:46 PM »

Quote
I have a rotary B&W ...

I had two rotary "antenna" switches used for switching the 21.4 MHz SDU output from two receivers to one SDU.

Guess what?

Poor isolation between inputs even at the microvolt level!

I ended up manually transferring the SDU input cable between receivers.
Logged

WB6BYU

  • Member
  • Posts: 20896
    • Practical Antennas
Re: RG-8X As Jumpers
« Reply #11 on: November 14, 2020, 08:00:32 PM »

Quote from: KE8BFN

Typical Set Up:

     TS-820s - AT-820 Manual Tuner - SWR Meter - Antenna Switch Pos #1




What are you using the SWR meter to measure?

That’s a serious question, because they are most commonly
used for adjusting an antenna tuner, and for that purpose,
need to be between the radio and the tuner

Radio -> SWR meter -> tuner -> antenna

Now, if each radio has its own tuner and SWR meter,
and you are just using this meter more to check for
catastrophic antenna failure, then placing it in the common
antenna lead might make sense.  But in that case, you can’t
use it for adjusting any of the antenna tuners.

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: RG-8X As Jumpers
« Reply #12 on: November 14, 2020, 08:31:32 PM »

Quote from: KE8BFN

Typical Set Up:

     TS-820s - AT-820 Manual Tuner - SWR Meter - Antenna Switch Pos #1




What are you using the SWR meter to measure?

That’s a serious question, because they are most commonly
used for adjusting an antenna tuner, and for that purpose,
need to be between the radio and the tuner

Radio -> SWR meter -> tuner -> antenna

Now, if each radio has its own tuner and SWR meter,
and you are just using this meter more to check for
catastrophic antenna failure, then placing it in the common
antenna lead might make sense.  But in that case, you can’t
use it for adjusting any of the antenna tuners.

I am using the SWR meter on the radios to adjust the tuners and the standalone meter after the antenna switch to watch for a short etc.
I guess I could put the SWR Meter-Tuner-Antenna on one position of the switch and just the radios on the other positions.
Logged
So Many Toys.......So Little Time!
Pages: [1]   Go Up