Foundations of Amateur Radio When does knowing more make it harder? 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 To listen to the podcast, visit the website: http://podcasts.vk6flab.com/. You can also use your podcast tool of choice and search for my callsign, VK6FLAB. Full instructions on how to listen are here: https://podcasts.vk6flab.com/about/help All podcast transcripts are collated and edited in an annual volume which you can find by searching for my callsign on your local Amazon store, or visit my author page: http://amazon.com/author/owh. Volume 7 is out now. Feel free to get in touch directly via email: cq@vk6flab.com, follow on twitter: @VK6FLAB (http://twitter.com/vk6flab/) or check the website for more: http://vk6flab.com/ If you'd like to join a weekly net for new and returning amateurs, check out the details at http://ftroop.vk6flab.com/, the net runs every week on Saturday, from 00:00 to 01:00 UTC on Echolink, IRLP, AllStar Link and 2m FM via various repeaters.
“We, the unwilling, led by the unknowing, are doing the impossible for the ungrateful. We have done so much, for so long, with so little, we are now qualified to do anything with nothing.” ― Konstantin Josef Jireček
When I was a Novice, I didn't have a CLUE what I was doing, but managed to work the world. (Of course, propagation was a little better in 1972, especially if you lived near the beach). Too much knowledge usually results in the paralysis of analysis.
The key factor in the original story is that it's a basic receive-only setup, so a lot of things really don't matter. There's more to it, though. In 1972, as a Novice, you only had 3 HF bands and 1 mode. This radically reduced the choices to be made. Your transmitter was probably a simple MOPA and would match a wide variety of load impedances with little trouble. And you probably used crystal control. Most of all, you had low expectations. ANY QSO was a good QSO. Nope. Not enough knowledge does that. If someone has "paralysis of analysis", it's because they don't know what's really important to making something work. So they focus on the wrong things. The person with more knowledge knows what is and isn't important to consider. ---- Some guidelines: "Paper is cheaper than parts." "If nobody does it that way, there's probably a very good reason." "Fast, cheap, good - pick any two." "Nothing is ever difficult for the person who doesn't have to do the work." "Failing to plan is planning to fail." "Sometimes you get there faster if you slow down." "Don't give a $100 solution to a $1 problem." "If you can't find it when you need it, you don't actually have it." "Often the improvement in a receiver is in what you don't hear"
One of my favorite quotes is, "It's so crazy it just might work". Your plan just might...but if it doesn't you'll learn from it. Good luck.
I was a shortwave listener and a VHF/UHF scanner enthusiast for decades before getting a license to transmit. That experience taught me that almost anything will work for recieving. SWR doesn't matter. As long as you get some metal into the air and connect it to a reciever, it's almost difficult to produce a deaf antenna. Recieving is all about signal to noise ratio. Detuning an antenna to make it a worse match at the desired frequency decreases both signal and noise together, so doesn't affect SNR much, until the signal drops so far that it's similar in magnitude to the reciever's internal noise.
If all that was simply an attempt to get a receive antenna up, than there is WAY more there than necessary. I have a friend who doesn't have cable TV, still watches the broadcast locals and supplements with streaming and the internet. I put the "antenna" in his attic. It's nothing more than the exposed center conductor of RG6 stapled to the roof rafters. The other end runs to a splitter in the basement and it's distributed from there. Granted, he's in relative close proximity to the local transmitters, but it's simple, reliable, and it was fast and cheap. Listening doesn't require all the stress we put ourselves through for transmitting. There's a reason why a wire wrapped around a collapsible improves the reception. Surface area and signal collection. Bigger surface, more signal collected, kinda like tin foil on the rabbit ears.
