Low-band NMO VHF-High performance?

[Anderegg]

NMO36, tuned for 40MHz CHP. Puting together a new car, and would like to install a QMA Motorola Multiplexer I have, and use my low-band antenna dual purpose for VHF-High. What type of performance could be expected from a low-band whip on 155MHz vs a triband Laird or Larsen small antenna. The local VHF channels do not talk enough to allow comparison testing.

Paul

 

[markclark]

The VHF High signal killer is the Low Band coil that is nowhere near the resonance needed for High Band performance. I know this from personal experience. Try to install a diplexer and run two antennas.

Good luck.

 

[Anderegg]

For RX only obviously, would it be worse than a tri-band NMO150/450/7800 antenna? VHF is so hard to test in my county, as it only lights up once in a blue moon, and when it does, it is always horrible signal strength at best.

Paul

 

[prcguy]

Yup, running a base load antenna 3X lower than the operating frequency doesn't work very well. You should get better results using a VHF 5/8 wave like a Larsen or Maxrad tuned to 155 then it will operate as a 1/4 wave tuned to 51.6MHz. Not perfect but should be useable for CHP.

 

[petnrdx]

As PRCguy says, you REALLY want to go the other way around. I know from experience that the Lo Band antenna is deaf as post
at VHF Hi. If your 42 mhz antenna is RX only then get an NMO-150 and use it for both. Will work well. If your Lo Band antenna
needs to be for TX also, then you will need two antennas.

 

[merlin]

The low band antenna will resonate near your target frequency, at least enough to stay under 2:1 match.
Not much option going back and fourth between bands.
Use strictly for 155, you can use an outboard coil and small cap to 'tune' the antenna.
Best bet is something like Maxrad, Larson, or Browning 5/8 wave 150.
I tried the 6 meter antenna on 2 meter and neither band had optimal performance. I went with the Browning 5/8 wave AND the Sigma SE-HF-X80 tuned 5/8 wave at 52 Mhz.