We seek to understand and document all radio transmissions, legal and otherwise, as part of the radio listening hobby. We do not encourage any radio operations contrary to regulations. Always consult with the appropriate authorities if you have questions concerning what is permissable in your locale.

Author Topic: 450 ohm ladder line  (Read 373 times)

Offline ke8dnu

  • Newbie
  • *
  • Posts: 9
    • View Profile
    • qrz
    • Email
450 ohm ladder line
« on: September 15, 2018, 1343 UTC »
I posted this on the LWCA message board as well...

Currently on my antenna, I'm using a an inverted-V fed with good coax. However, as with almost all coax, there is some LPF (loss per foot), and with a 4mw output, that could result in pretty substantial loss at the end.
The transmitter is approximately 50 feet or so from the antenna at this time, and will remain at that distance with the new setup, however, I am looking to use 450 ohm ladder-line as opposed to traditional coax.

Is anyone else using this method, and if so, what kind of improvement in signal (if any is to be had) are they noticing?

Adam/KE8DNU
Amateur Extra, ARRL Accredited VE

Offline Exo

  • Full Member
  • ***
  • Posts: 168
  • HF aficionado.
    • View Profile
Re: 450 ohm ladder line
« Reply #1 on: September 16, 2018, 0003 UTC »
450 ohm ladder line will be nearly zero improvement over your 50ft of coax.
And it might possibly be a lot worse.

The reason for that is the impedance mismatch.
Of course, the impedance mismatch could be compensated by cutting a specific length of line.

50ft of coax has negligible loss at HF.

Unless your frequency-specific inverted-Vee dipole antenna is more than 150ft away, the use of 450 ohm ladder line is not appropriate.

The main applications for 450 ohm ladder line are:
1. Very long transmission lines for HF
2. High power applications
3. Use with an antenna tuner for multi-band transmit applications

But, changing from an inverted-Vee antenna to a ground plane antenna would be a big advantage for 22m HiFER.
That's due to the take-off low angle radiation pattern, which makes way more difference to the signals at 13 MHz than a few dB of coax loss.
« Last Edit: September 16, 2018, 0011 UTC by Exo »
Exo
HF aficionado. On the coast of northern California.
Various receivers, transceivers, and broadband antennas.
kiwiSDR receiver on private LAN for multi-freq HF monitoring.