Question for HF users

how much interferance you recieve while your vehicle is running dpends on things i knwo little about apart from some vehicles have more of it than others.

my biggest source of interferance is my fridge but the engine does provide some. I have made calls on the move but by far and away my best conditions are stopped with everything off

Depends on the vehicles. In most late model fuel injected vehicles (petrol) and diesel (common rail) HF is virtually unusable if the engine is running due to interference from the injection system.
Many accessories on vehicles like GPS, fans, a/c, suspension, traction control etc cause huge amounts of noise and to stop it is nigh on impossible for many of them. I used to install HF's for work and we gave up on Landrovers with the advent of the TD5 engine as it made so much noise the receiver in the radios couldn't pick anything up.
Many vehicles would also suffer from interference from the auto tune antenna if it tuned while the engine was running. Some of the V6 Pajero's you can stop the engine by tuning a particular frequency.
We usually advised buyers that the HF was basically for use only when stationary with the engine and accessories turned off. Some vehicles can be shielded and suppressed to the point where the radio will work reliably on certain frequencies but it is nearly impossible across the whole frequency range.
The two radios with one selcall may work (depends on the brand and model) but remember if a base or another user selcalls you then both radios will respond. Most users with multiple radios/vehicles have a different selcall on each radio or in the scenario of multiple radios only ever is one in use at a time.

Tim,

I'd agree with the above - too much interference from too many sources for hf to be much use for communication when on the move. I'd expect the selective calling function to work fairly well, keeping the set muted until it receives the call; maybe that's sufficient for your purposes?

The other issue - using a different selcal number you might select one already in use by someone else. (For at least one of the networks these numbers are published on the web so it should be possible to avoid a selcal collision.) Don't know how the network would respond to 2 radios on one membership, or a request for a second selcal number, but probably with an invoice!

Cheers

John

Tim. I have a Codan NGT HF radio in my diesel 'Cruiser, I installed it myself without any filters or suppressors and get no static or interference even when mobile. The NGT Codan has a feature called "Easi-Talk" which filters out a huge amount of background noise, this can be turned off/on by a button on the handpiece.
Someone suggested that two radios would attract extra membership fees. I'm pretty sure the club I'm a member of doesn't do this. One membership fee includes your partner and I presume a second radio.
I don't know about the sell call question ?.

Rob.

Tim

For the first couple of years I could not use my HF while mobile.
I then install a NES10-2MKII speaker. This solved the engine interference but not the fridge. For the fridge I installed a switch on the dash, to isolate the fridge when I need to use the HF.

While mobile comms do work for some, at times, I think it safe to say that the majority of HF users would expect to comm with bases and each other, at the start and end of the day, while static. Much more practical, mainly because HF reach is enhanced while the sun is low and to also take advantage of the lack of vehicle generated noise. That said, it is common though for users to employ selcall scan while mobile - an incoming will set off the alarm, and then the user can find a nice spot to park while responding in voice mode.

If the interference stops you hearing the signal clearly, then Selcal will also have trouble decoding the incoming call.