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Thanks guys, all the videos have been great, I enjoyed watching them. He'll be a transmission line expert in no time :)

You're a legend, that 2nd vid was the one! Many thanks :)

Hi all, I am trying to help out a junior engineer at work, who is studying for his full licence. I'm trying to find a video I saw years ago (I think Bob85 posted it iirc). The video was by an American HAM who was giving a demonstration of transmission line theory by using two 20' copper tubes...

They were the regular type, not the "C" variant

well I've replaced the 2nd pair of pills now and I have advised 50 - 60W max input drive. Hopefully I don't see that amp again.......... :)

RG213 has a 0.66 velocity factor which is the same as RG58, so measurements should be the same for the lower half of the antenna incuding the cap. In that video the stub is made from Westflex coax so the length of the stub will be different when using RG213 for the stub. The 561mm sounds good to...

But what about the bragging rights of running big power? Surely that makes the S meter move further? :P I think the sweet spot is probably around 4 -500W, after that the law of diminishing returns kicks in as you say. It would be much more effective to put more money into your antenna system at...

Appreciate the replies guys, you're saying exactly what I thought you would. I just watched the demo video again and it was doing 750 - 850 peak on 80W drive @ 14.8V. Sad thing is he already has a KL703 which can do the same power out and he was trying to get something that did a bit more. I...

Hi all, A friend of mine recently imported a 4 pill amp from a builder in the US and has managed to pop pill number 1 and blow the base emitter 10 ohm resistor. He contacted the box builder and was told that replacing pills 1 and 2 with a matched pair and replacing the BE resistor should be all...

I've made a gainmaster from RG213, and it worked great. I have some 1/2" heliax here and I've started to make one out of that. This video should help out a lot

No need to apologise, I critiqued the way you asked the question because it lacked clarity and was wide open to misinterpretation, I did not, in any way, imply you were dumb. I am a "dumb CB'er" too, I don't care so much for the HAM bands, although I didn't claim to have the answer you were...

I now feel like I didn't read your question properly, lol. You did specify director elements. You mean specifically why do the director elements get progressively shorter as they get closer to the end of the antenna, tbh, I don't know :) I would assume, that as the elements get progressively...

I think that has more to do with how you phrased the question than it has to do with the antenna guys on here ;)

Do you mean taper in that the reflector is longer that the driven element and the directors are shorter? If so, that is because an element that is longer, or lower in resonant frequency than the frequency of operation will reflect the RF away (towards the front of the antenna) and a shorter...

Hi, I know there are some professional radio engineers here so hoping one of you are familiar with new Tait radios :) I am really struggling to find information online for the new DMR tier 3 tait radios. I am looking to program some Motorola radios in DCDM mode, but the radios may need to talk...

The difference is you are trying to create a path for RF to ground (or in this case the vehicle chassis). DMM's use DC to test resistance not RF. If you google "RF skin effect" you will find the RF travels on the surface of a conductor not through the middle of it, so a wide copper strap or...

He has a poor antenna installation and CMC's on the braid, he wants to fix that before he starts adding more wires into the mix.

It's not something I've done before and I've been putting this off for years :) It either has to be repaired or I throw it away, and I hate throwing things away lol. I've used two 1mm thick discs of nitrile infused cork and it is working as a brake. Once I get it back together I'll mount a stub...

So I posted the same question in a rotator repair group on facebook and someone replied back that the original material is made from cork. After a bit of research it seems cork is used as a friction material in sewing machine clutches. So I bought a sheet of rubberised cork sheet and cut some...

You are correct in what you have learned, the larger diameter element will give more bandwidth than a smaller diameter element, the only question is, how much? In relation to the wavelength you are operating on the element diameter is changing by a miniscule fraction. In short, just repair the...