Great job Tim. The cap hat is always more effecient than a loading coil, but most don't emply a cap hat due to mechanical restricions. I advise all to use a cap hat first with an excellent ground radial field, THEN add a coil if needed. This will keep losses to a minimum. It's what we do in AM commercial broadcast when the tower is electrically less than 70 degrees or so. 73 OM.
Nice! I designed a 3D printed coil a while back and this vide would have been so great to have to better understand why coils are built the way they are! I understand them much better now!
First class as always mate. What I find amazing is the contacts you can make such an "inefficient" antenna. Just goes to show that what matters most is just getting some RF into the air.
Tim - I dont operate Mobile like I did 10-20 years ago, but I had great success via a capacitive Match at the base of my 8 foot cut for band "Hamsticks", I believe I used simple 1kv 470pf disc caps for 75 meters, and 240 pf at 40 meters, you could select the right capacitor for the best SWR. If you operated "off resonance" in a particular band, that capacitor sure would get hot! But it worked well, and more importantly survived the weather well, snow, ice, rain etc. I did try the coil matching technique as well, but it did not survive the winter elements at all. Worked a ton of DX via this technique. 15 meters was a blast, but I could also maintain regular contacts on 75 and 40 meters, by simply swapping 8 foot Ham Sticks around. Ahhh, the good old days.... 73s I like your YT Channel de Jerry KC2UT
I watched you in your car doing the contest. VERY interesting.. I talked about you at our weekly club meeting here in Brussels Belgium (BXL) I was wondering about your antenna. This video is what I am looking for Thanks
very interesting - thank you Please correct me if I am wrong - is adding the capacitor across coil - lowers the q There is a formula for calculation of C for capacitor to correct the Q of the coil X_L = 2 * π * f * L X_C = X_L * (1 / QDesired - 1 / QCurrent) Capacitance (C) = 1 / (2 * π * f * X_C) where: - X_L = Inductive Reactance - X_C = Capacitive Reactance - QDesired = Desired Q Factor - QCurrent = Current Q Factor Am I correct ? (I am not trying to correct anybody - just to verify if I am wrong) I have created a soft for myself to calculate parameters for the coil to shorten the 1/4w vertical - for 2m vertical for 7.1 Mhz - with a coil in the middle it is 57uH and Q for the coil was 420 - adding capacitor of 470pF gets it close to Q 50 which makes the antenna wide band Soft is over 200 lines long so I can not show it here - it is in PowerShell so it runs on any Windows PC or Mac with Powershell installed. I am learning so I might be wrong.
Hi Tim, is there a way to measure the insertion loss of a loading coil or a way to measure its efficiency at specific frequencies? If so, how would you go about this? Knowing this information would be extremely helpful for people running qrp.
There are many more variables to this you even get capacitance between the windings, Plus many more things like the pitch of the windings, I'm not going to give away info that went into the two years R & D of the Slidewinder dx coil, But basically it wasn't just some wire wound on a former.
@@timg5tm941 Good video Tim, Most of the foundation theory of loading coils was covered so you have done quite alot of research, It was good that you showed center & top loading isn't as good as some may think.
@@Tantalicdavid I agree about centre loading. So many think the enhanced current pattern is the be all and end all but forget about the extra coil resistance. My next video about this directly compares examples of well known mobile centre and base loaded antennas.
@@timg5tm941 I have seen big mobile whips with some curious coils. I have all the Hustler ones (Except maybe 17m) but the one I saw was far bigger, and in red fibreglass. looked like an oversized CB antenna,
We could do all of this, and still not be heard. Simply add a gigawatt amp and your all set, as long as you keep the output power below 1.21, NO flux capacitor is required.....
