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Any Shortwave Radio Tips for a Noob Considering the Hobby?
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Bud:
I worked the globe FROM MY CAR, the radio was Icom 706 mk iig into a top loaded whip antenna mounted on the trunk.
(@edy: you do not want to get into mobile ham radio  ::) )
fourfathom:

--- Quote from: bob91343 on December 18, 2019, 02:05:14 am ---You won't hear much but you can find a lot of signals by using a spectrum analyzer.  They are very sensitive and cover a wide frequency range.
--- End quote ---
This is one of the nice things about the SDRs like the ones from SDRplay and Funcube.  Most of the programs you use with the SDR will display a spectrum and usually a "waterfall" spectrum plot, over a 2 MHz or wider frequency span.  This makes finding signals easy, and to listen in you just have to click on the display.
bd139:

--- Quote from: Sal Ammoniac on December 17, 2019, 11:22:58 pm ---
--- Quote from: bd139 on December 17, 2019, 10:52:17 pm ---Air traffic is fun to listen to. I live under Heathrow approach. Also at air shows.

--- End quote ---

You're probably listening to air traffic on the VHF bands, which is quite different from the air traffic on the HF bands. HF air traffic happens when aircraft are outside the line-of-sight range of VHF comms (like over the middle of the Atlantic or Pacific oceans) and consist mostly of position and altitude reports at infrequent intervals.

--- End quote ---

Yep that’s exactly it.
edy:
I am having fun with the radio, every day I scan at different times and make notes of what I can pick up with my wire. Sometimes the wire makes no difference... I clip it on or take it off, I still hear the station! Sometimes I get better reception by grabbing on to the antenna with my hand! When I remove my hand the signal goes to fuzz! Sometimes it will skip a station when it is doing the autoscan memory (ETM), but I will manually go to that frequency and behold I have a signal there (weak but still audible)!!!! I guess now I know the ETM is *not* perfect in finding everything, but it would be a long process of going through every frequency from 2300 to 21950 in 1 khz steps to find stuff!!!

Also I noticed some broadcasts in the high 3000's occasionally at night where people are talking about HAM radio stuff... sometimes I can hear it. And sometimes it sounds like people talking (not a radio show or religious stuff) but I can't make it out. It sounds muffled, like the adults in the Charlie Brown cartoons. Is that because it is on a side-band?

I want to make a magnetic loop antenna and found this excellent video (further down below). I was going to go out and spend money on copper tubing and air dielectric capacitor, which is beautiful and all, but I think I will start with something much simpler with stuff I have laying around at home! I only need to buy a couple of variable trim caps but the cheaper type which I can hook up in parallel for fine-tuning, like these:

CAP TRIM 15-160PF 13MM PCST PL and CAP TRIM 13-44PF 8MM GRN PCMT. Remember these are for receiving, not transmitting. I know they can't handle high voltages but if I'm using this to receive only then should be ok?





I figure if I hook up a couple of the 15-160pF and the 13-44pF in parallel, at the minimum setting for all 3 I could get down to maybe 13+15+15=43pF. If I add a switch on the parallel branch to the 2 larger trim caps (which I would connect below the 1 smaller one), I could take out the larger caps from circuit and then be left with only my 13-44pF trim in circuit. So I could trim 13-44pF, and then to go higher in range I would flip the switch and have all 3 caps and maximum be 44+160+160=364 pF. So I would be able to range from 13 - 44pF with switch one way, and then continue with 43p - 364pF with switch other way. I hope that is a good enough to cover my 2300-21950 kHz range of the radio. Otherwise I'd have to add another large trim cap and then push the max up to 44+160+160+160=524pF. I can buy the trim caps for about $2-2.50 each so all together about $10 in trim caps unless I can salvage something at home. Something like this? What about the coax? Do I use outer mesh only? See photo below and also video:



As far as loops go, it sounds like most people are using about 10 feet length of wire/tubing so approximate diameter is 10 foot/pi = 3.2 feet or approximately 1 meter wide. Then they make the smaller loop 20 cm diameter (about 1/5 ratio) which hooks up to the mesh and inner conductor of your coax. The video below actually shows them using a coax. I believe they are shorting the mesh/conductor together at different points so it becomes one. This method allows the antenna to be flexible for portability and then you just rig it up to a mount that supports it in a circle when needed. I may build something like that because it is easy to store away.

Any suggestions? The video starts showing these about 16 minute mark... using coax cabling. And then at about 20:30 mark he shows it made of coax for both outer and inner loops, simple, he called it "Cheap as Chips".  :-+



james_s:
Does your radio go down into the 200-400kHz range? One of the things I enjoy doing is receiving NDBs, not too interesting to listen to honestly, all they do is broadcast the callsign over and over but fun none the less. The best explanation I've ever seen is that it's a bit like bird watching.
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