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Or just install the radials that should have been there in the first place. The Antron A99 has a radial kit that'll mitigate almost all problems especially when combined with a decent RF choke at the antenna feedpoint - 12 turns of RG58 round a FT240-61 toriod will choke off pretty much...

The only reason for the oil is to dissipate heat and that's not a good thing because it means your RF power is being turned into heat by the dummy load of an antenna instead of being radiated as a usable signal. Every watt that is heating up that oil is a watt not being radiated.

Sorry but that's rubbish. If you want some evidence then look at my contesting history in any of the CQ WPX, CQ-WW, ARRL or IARU contests when I was having a serious go at it. I ran 100W low power entries using a G3TPW Cobwebb at 32ft and an 85ft inverted L flat top at 24ft. The Cobwebb was...

You're welcome. Told you it was good news and because you have a good RF ground. ;) Chapter 3 of the ARRL Antenna Book on RF grounding has a nice chart showing how as you improve your RF ground the resonant frequency of the antenna drops for a fixed length of antenna. So for anyone wondering if...

It ends up being quite simple in the end. Being sat out in the countryside with the engine running and seeing S0 on the S meter on an empty channel even with the pre-amp on and actually being able to understand what people are saying with any signals you hear which are at S0 and the only...

It isn't. It's a ground plane end-fed antenna. Stop thinking of it that way as you're just confusing yourself. No it isn't, it's called a dipole. "Dipole" refers to an antenna fed in the centre with two identical conductive elements (hence the reason that an A99 on a mast isn't a dipole...

Yes Kirchoffs Law applies. RF is nothing more than alternating current at a specific frequency which is fed into an antenna that radiates a charge. Going back to the first post... First of all... The Imax 2000 and A99 are not end fed dipole antennas, they're an end-fed antenna. The only...

Yes it is. Now I'm going to give you some good news. The reason the SWR is high is because you've actually got a good RF ground. I'm betting that the SWR is lower on Ch1 than Ch40. If so that's definitely the case and you'll need to cut the whip. I have a very good RF ground on my vehicle and I...

Spend some money and buy either an antenna analyser like the MFJ 259/269 or a nano-VNA if you're going to start building antennas. They'll save you a load of time and effort chasing red herrings.

Not the charts I was looking at in the ARRL book. They cover both ground and elevated. I know the OP was talking about elevated, not ground mounted. You misunderstand. The shortening of the vertical element has to be done as a result of the improved efficiency of the RF ground. And funnily...

Yes. The ARRL Antenna Book section on grounding, chapter 3, has 30 odd pages descirbing different options, what's going on and plenty of charts which graph gain vs both radial lengths and the number of radials and it also has graphs showing how the resonant frequency of a fixed length antenna is...

The more you improve the RF ground the shorter the radiating element needs to be for a given frequency. Performance increases won't really be noticeable to be honest although if you could put a RF current meter on your coax you'd notice a small drop in common mode RFI if you weren't using a...

That antenna might be a commercial product of the type of antenna W8JI was describing but what W8JI was describing was the generic concept of a 1/4 wave with sloping radials rather than a specific make/model. Sloping radials are mentioned in the ARRL Antenna book in the grounding section.

I've been using the whip from my Sirio 5000 for the last few years on my Little Tarheel II.

Here's a video I did with my Little Tarheel where I used the stock whip, one I robbed from my Sirio 5000 which is something like 6ft 4in, and finally a 10ft one.... Suffice to say it's definitely worth sacrificing 6m and using a much longer one.

Welcome to the Sirio Blizzard 2700 with anti-vibration ring. If it looks very familiar to some that comes as no surprise. Yep....we have yet another repackaging of the Sirio 827 being released as a brand new antenna where all they've done is kept the same core antenna and made changes to...

Same here in Blighty, the only towers that sell are portable tilt over versatowers on trailers and they'll go for silly money. Not many people have the time, money or motivation to dig a four cubic feet square hole to pour concrete in to create a proper base for a tower to mount to.

What the heck for? Just use RG58, the lengths involved are so short there's no benefit to be had from using even RG213.

Quite ironic you linked a video from Mike who in the last year he was posting them spent a lot of his time posting videos undoing modifications like this. I'm all for doing a modification if there's any actual improvement to be had but with this there isn't. HELL IF YOU ACTUALLY READ THE TEXT...

Without using proper test gear how do you know receive is off frequency? I got told I was off frequency once by people in the town next to me. They were using CBs, I was using an Icom 7000 with a TXCO. Turns out that everyone on CB in that town had their rigs aligned by the local rig doctor. He...