Foundations of Amateur Radio

The other day one of my non amateur friends asked for some help. He wants to set up a receiver for his bush fire brigade that's available via the internet so his community can listen to the communication channels when there are fires around, or when a volunteer is out of radio range but still wants to hear what's going on.

His question was about hooking up an antenna.

We started to discuss what he already had and it turns out that he has enough coaxial cable in either 50 Ohm RG58 or alternatively 75 Ohm low loss quad shielded satellite TV coax.

He's not an amateur, won't be broadcasting and just needs it to work without spending too much money.

We then started talking about antennas and he had a tuned whip and a generic scanner antenna. Turns out that the tuned whip was for 78 MHz and he needs to listen to 164 MHz, so I suggested the scanner antenna, so called broadband, but no actual specifications.

Then we talked about how it was going to be mounted to his metal roof. Tek screws to the iron, a CB mount with solder pads. That started a conversation about waterproofing and coax rot, termination and then the ground plane.

I could get my antenna analyser out, drive to his place an hour or so away, help him install and test it and then decide that we need other options. We might still decide to do that, but it will be driven by what happens at his installation.

If you're a licensed amateur with a little experience, this story will leave you with a whole lot of but, but, but.

If you're not, then you'd come away with, that's pretty reasonable, let's go.

What I find fascinating is the gap between those two.

On the one hand you've got knowledge that says this isn't ideal, who in their right mind would hook up a random antenna without the proper ground plane with an unknown feed point impedance to a 75 Ohm coax, using solder pads on the top of a roof. There's more of course, but those are the big ticket items.

On the other hand you have an antenna, coax, connectors that fit and a high likelihood of noise coming from your radio.

I'm not going to pretend that the choices we made over the phone are the final ones, or that it will even work as described, but we discussed that and the selection of parts gives us the highest chance of success, and rather than give the right answer we went with the closest we could get without spending a cent.

The gap between knowing and not knowing can be perilous, but it can also be used as a map to navigate from one to the other.

Is this going to work? Who knows, too many variables to be certain, too many unknowns.

Sometimes ignorance is bliss and sometimes knowledge is a burden. Finding the balance is a lifetime of learning.

I'm Onno VK6FLAB