Permanent Antenna Install - Homebase

After a week of playing around with bits of wire Ive decided on a permanent install for the CB game.

Im running a wire for general HF use but picked up voice the other week in the CB band, but could only ever hear one side of the conversation.

I decided to throw up a vertical wire and have a listen, the noise was appalling, 9 S points of it, nothing particular just white noise.
So moving forward I made a more stable dipole out of bits of fibreglass poles with a wire in an attempt to get it a little higher, but still only around 28ft to the tip, It certainly gained 3/4 S Points in RX over the horizontal wire I was using but RX was just generally noisier, so not to happy with that.

Yesterday we had strong winds and torrential downpours and my dipole was suffering and I pulled it down before it broke apart, Ive since decided to order an A99, I dithered about getting an IMAX 2000 for a while, well about 6 hours or reading about pros and cons between the two. Im using this purely for CB, I find DX works fine of the Horizontal Wire, so the vertical is for local chat and finally decided on the A99 mainly dues to size and weight and also neighbours.

Ive found UK25 around here has quite a bit of use, 10/15 users spread out over 5 - 40 miles or so, so im hoping ill be able to get in with the chat, Ive also come across the discussions about whether to isolate the 99 from the mast, use of the mast as part of the antenna, TVI, etc etc. I won't really be able to use radicals here, so ill be limited on my options but it should be interesting to play, ideally though saying that, I d like the antenna to go up correct the first time and then just leave it.

I have 18ft of mast that will be 10ft off the ground with the A99 on top, Im adding a boom about 1.0M in length to place my VHF Antenna onto.

Fun times

If you're not going to use the radial kit then don't isolate the mast from the antenna and hope the length is luky enough to be right to make up for the lack of RF ground. Do use a RF choke at the antenna feedpoint (make a coil of 5 turns of coax with a 4.25" diameter) to prevent the coax being used as part of the antenna due to a lack of RF ground but if you're not using the ground plane kit don't have the coax below that touching the mast otherwise you completely negate the point of the choke.

Yes I’m with you.
Il use 20ft of mast in this case then in the hope of making up the RF ground.
Yup ill do the Choke, ill pop out to B&Q and pick the pipe up.

Regards the Coax not Touching the mast, that make for an untidy install, OCD ATTACK ARGGGH!

How to get around a flappy coax cable is the nest hurdle, nut I have an idea.

Would that also be the case for the VHF/UHF Co linear, that’s just on the pol plugged in and the coax tape to the mast.

Question, the assumption being the choke needs to not touch the mast also ?

CyDer DrinKer wrote:

Yes I’m with you.

Regards the Coax not Touching the mast, that make for an untidy install, OCD ATTACK ARGGGH!

Question, the assumption being the choke needs to not touch the mast also ?

It doesn't have to be an untidy install.

Keep the choke it off it. Rather than making one from a coil of coax I make mine using a FT240-31/43/61 toroid depending on frequencies I want to cover and then put the whole lot into a weatherproof box with a SO239 connector at the bottom and a short 6" tail of the RG58 sticking out the top with a PL259 on for connecting to the antenna. For 10/11m onlny use a FT240-61 with 12 turns of RG58 around the toroid - that'll give you >8k ohms of choking, enough to pretty much guarantee killing off any common mode RF as pretty much anywhere else will be a path of less resistance for the unwanted RF current to flow. Ones made using a ferrite are more wide band and are resistive choking instead of reactive so you don't get the risk of making it worse if you get it wrong .

You only need to keep it a centimetre or two off the mast, not feet away. You could just make up some spacers from a bit of plastic and secure them to the mast with jubilee clips. You may even be able to find some P clips with a long enough "stalk" or use cable cleats that Screwfix sell.

Cool.
Ill make some spacers, Ive got a plan, going to enjoy setting this all up

Had a great day doing radio stuff, making up the RF Choke or the many other names it appears to go by!
Varnished the 99 with Yacht Varnish as recommended, fitted it together and added the choke.

Ive not got much further yet as ive a boom to add for another antenna, but a quick test at ground level gave me a read out of:

26.000 - 2.0
26.500 - 1.4
27.000 - 1.1
27.500 - 1.4
27.995 - 2.0

Happy days, I’ll change the resonance moving forward, probably got to halt for a few days as the weathers turning pants around here.

You should find as you raise the antenna up the resonance also rises as you get reduced ground losses due to the low height. Putting it up 16ft or more should see it go up a couple of hundred kHz. I wouldn't think about making any adjustments until you've seen where it is when it's up where it'll finally be going on the mast it'll be on too.

You can have the coax a bit closer than that

Have you got 6 turns on that ???.

Ok Connor I’ll do that before any adjustments.

Hi Alan, ended up being about 5.5 turns, I was so busy making it look uniform I ended up with half a turn more than planned, I know I’ve read too many turns for a specific band can cause degradation, but I’m assuming that means more than half a turn?

Up she goes!!





Squeaky bumm cheek, sun was shining and then mid operation the winds and rain hit and there was no going backwards, ended up yelling to the other half to come and support the bottom while I arsefarted about with nuts and bolts, Morale of the story, Im not as fit as I used to be and this is a lot heavier than the last set up I installed.

I knew it was going to be a little more unbalanced that a single twig, to be honest it was a PITA, but its up, does not look high but when like me you don't do heights and your on the top run of the ladder, its high enough.

Really pleased with the tuning, 1:1 exactly on the part of the band I wanted, quite noisy with around 8 S Points of noise on the Muppets band, don't know what's acceptable today in this band, I know a lot of electronics are not notched for the CB band.



As for contacts and the improvement heard locally compared to the Wire......dont know yet, nobody is on, typically.

I do have more mast and so more scope for tasing it higher but ill work it at this level until im happy nothing needs adjusting.

Sadly because it's an unlicenced band there's often a lot of noise on it. Where my house is I get S7. I drive literally two houses up or down from mine and it drops to S3. It's not in my house so it's something one of my neighbours has causing the hash.

If it comes to it you can get a noise canceller like the MFJ 1026 which will massively improve the situation.

Interesting, I’ll look it up, today has been +10 of noise.
The radio I’m using has a NB switch which drops the needle a S point or two but not convinced it’s improved RX much

Okay looked that MFJ unit up, that’s a lot of expense and they recommend a SECOND outdoor antenna that receives as well as you main antenna, could you imagine 2 Antron 99’s OMG!

Seriously though, I guess you could use some wire stealthy over the roof or something to mimic the 99 on receive, but it’s £300 unit before doing anything else, wowzers, reviews vary wildly and many say it’s very hard to find that sweet spot to null the noise out.

Perhaps I’ll start with some basics, I need to read up about grounding the shack I guess, possibly the 99 also ?

I found the A99 which I had to be very noisy compared to the metal 5/8 wave that I have now. from what I have read I am not the only one which has found this.

there was a good 2 s-points difference in the noise level between them.

My wire is just as noisy to be honest, a couple of s points down but it is running horizontal.
If a 99 is noisy over a silver rod then the question begs why and what can be done.
I’m going to read up online about grounding of shack equipment see if I’m missing a trick.
+10 of noise today makes the band useless, 10k seems pretty much the same

CyDer DrinKer wrote:

Okay looked that MFJ unit up, that’s a lot of expense and they recommend a SECOND outdoor antenna that receives as well as you main antenna, could you imagine 2 Antron 99’s OMG!

They come up for sale often around the £100-£125 mark. Also there's a few other companies which make a simpler version of those. It's actually possible to build one yourself and there are circuit diagrams online. Basically it works using a basic principle of AC theory that two identical waveforms of equal frequency and amplitude but 180 degrees out of phase completely cancel each other out. By feeding a received local QRM sourced signal from the receive antenna180 degrees out of phase with the one from the main antenna you can cancel out the noise.  

A receive only antenna doesn't have to be large. You can use or build something like the PA0RDT mini-whip Active Antenna that's only a few inches in size.

Circuit diagram:



Actual size...

Mudslinger wrote:

I found the A99 which I had to be very noisy compared to the metal 5/8 wave that I have now. from what I have read I am not the only one which has found this.

there was a good 2 s-points difference in the noise level between them.

Does your metal 5/8 wave have radials? Did the A99?

That makes complete sense,l appreciate the explanation, and that circuit board looks fairly simple although my knowledge of building boards is almost non existent, they does look doable tho, maybe lol.

Today I found a little 2CH CB handheld in the bottom of my radio box and it still works, so I pulled the main power switch on my house but sadly the noise did not go away.

Here is a link to my video. https://youtu.be/Gqm8uJT0uoc

Looks like you're in the same boat as me, it's a neighbour. Thanks to stuff having to be notched out on the ham bands the HF amateur bands are fairly quiet, even 10m despite what I get on 11m so I content myself with those at home.