So much, where to start…

Posted on by

Well hello, maybe your reading my blog on amateur radio – I had a very nice weekend off and relaxing/downtime getting things done, but with that there was ALOT be done with regard to Amateur Radio !

Where do I start… well, lets first say thanks to my good friend and fellow radio amateur Trevor (PA2TG) who has been absolutely amazing in offering me advice on what I’m about to talk about ! So here we go !

40ft Moonraker mast with 2 Meter JPole

So I have got (two) new masts, willl talk about the other in another posting one day, but lets focus on the the fibreglass 40ft one for now.

Despite Covid, nature is still making some lovely flowers… time to go home after walking the dog, finish work and make a cable

I took some careful time rigging, i used the lightweight rigging but I really didnt want to start with. This looked good, and I got the mast upto full height. The problem then become apparant that my coax was now too short ! At 30m in length, at the time that seemed long enough as i was using my buddipole then and the coax was purely for experimental purposes.

Stripped of the sheath

The 40ft mast, is amazing, i will give it its own posting, in this post I want to concentrate on the coax I made for the mast as I’ve got some great advice, with more understanding about coax and loss that I could of ever asked for thanks to Trevor. I will point out that I ordered and received the coax a while ago, before speaking to Trevor, but I now know what to order next time, and it will make me appreciate what I have and how much power is being lost in the coax itself (you would think not much, but suprsingly, even the top quality coax, has some loss!)

watching the core slowly emerge.. the thread on this plug is very fine

So the Coax I had is https://www.radioworld.co.uk/rg-8-mini-coax-cable-50-ohm-military-spec-50-metre-drum – I really dont undertand all the specifications, and the price is right. I soon learned from Trevor not everything is what it seems and also websites on coax/loss confirmed what he had told me http://m0taz.co.uk/2017/11/coax-cables-and-associated-losses/ This cable is RG8, so of my 10 Watts going up the cable, on 2m 3.5w will reach the base of the antenna, so getting 1:1 S.W.R. is really important ! (3.5w !!?!LOL!>!!!)

first some electical tape, then heatshrink, looking rather good if I dont say so myself !

So I set about making my cable with the coax, I found this video most useful https://www.youtube.com/watch?v=GjO5ERU6a78 and following it found that I had created an awsome cable. Now if I was honest, that would be the end of it, but I have to admit I made rather hilarious mistake… In the video he does a continuity test, to ensure the cable is shielded and the center pin will deliver the RF power/energy.. I thought, well, why not strip the other end and check from both ends ! Great idea M7ALU ! So I stripped the other end.. measured continuity, come on 0… 1… a solid 1, not any reduction.. traces cable.. i’ve stripped the cable from the reel… So, when stripping cable, make sure you get the right one.

Putting a SO239 on to make sure it will fit on the mast / jpole connector ok

In the end I stripped. sheathed and plugged my cable in with loads of testing for continiuity, because I dont want to get it 40ft+ up and find its not working. Results soon.

a completed cable, both ends done, 0.0 on the power meter measuring continuity

Tomorrow she goes up, lets hope 1) I got the length right 2) it keeps working 3) The cable is good enough spec for me on 2m/70cm and 10 Watts of power.. We shall see !