SIGMA SILVER ROD

Hi, Bak to the old silver rod topic please. I posted about buying one on here and it not allowing me to SWR it. That was very well corrected by Sigma who I couldn't fault for service. It has been serving me pretty well apart from the fact that I can only raise it a couple of feet above the metal shed I use as a shack and it doesn't clear the roof of the house and we have fairly big trees the other side. It will work a lot better when I get it mounted just over the eaves. Having said all that I got the opportunity of having a second identical aerial given to me by a breaker who was upgrading. I am a natural hoarder and couldn't resist it. Got it home and it was quite badly weathered. Took all the section to bits and cleaned them up and added new jubilee clips. Got to the base part and the bolt through the bottom section had completely rusted up. Took me ages and a can of WD40 to get it to shift. Cleaned up the section and the bolt hole at the top of the plastic housing and undid the 3 screws at the bottom along with the 239. All going well till that old problem - the wire from the centre pin of the 239 was OK there but had come free from wherever it was before. I came to the conclusion that it must have gone to the connection at the top of the plastic mount which houses the screw to give connection to the driven element (Telescopic sections) One hell of a thing to do though, so I used a slightly longer piece of thinner wire which easily folds up when the housing is re-attached. I made sure it was insulated and did not touch any of the coil or the earthing part of the coil. The SWR is nearly on SET - obvious problem. Does anybody have schematic of the wiring of that coil or idea as to how it should be connected please?

think you might be able to pick up a diagram from google m8 or even a you tube video

Been all over the internet and unless I have poor search ability cannot find anything that helps. Trying to e-mail Sigma again and see if they will give trade secret away !! Probably not but will bottom it eventually

Plucked up courage to 'drift' out the plug at the top of the plastic cone and that released the coil so that I could inspect it better. Seems that I got it wrong in assuming the wire from the centre pin of the 239 went to the hole at the base of the plug in the top of the cone. When the coil was out it was easier to see where the wire should be soldered to. The location was on 2nd turn up from the bottom of the coil and the old solder was visible. I separated the wire, concerned about the heat from the soldering taking off the insulating lacquer on adjacent turns. I used a cheap iron because my 'good' one had popped about two weeks ago and the replacement hasn't arrived yet. I managed to get a good joint on several occasions only for the wire to break away each time. I've now uncoiled the wire and am going to make my own modifications. YES it would be easier to buy a replacement but I'm fascinated with aerials (since I started in the early 70's) and I want to make this one work.....

Having had a similar incident with my own half wave antenna I can relate to your situation, mine is a half wave vertical with a Ringo tuning section and the wire for tuning it came away from the SO239.
I felt the section of wire they had used was far too rigid and it had corroded and snapped off so like yourself being a bit of a horder I looked for what I had handy settling for one of the heavy copper core wires from a length of cable to connect a cooker with.  

After cutting it to the same length as the piece I was replacing then running an extension cable into the back garden I was able to solder in the replacement and I was just finishing up as the snow started. (soldering in the snow is not recommended)

The tuning on the antenna is perfect Mid 27mhz and the bandwidth is quite impressive too, even though it is currently on a twenty feet of extension poles which doesn't clear the houses around me I have been able to make contacts all over Europe.

Do let us know how your project gets on, tinkering with antennas is one of my faveroute aspects of the hobby.

Alan

Well done Alan. My theory is there it's just a question of adapting something that doesn't want to be flexible. I have come up with a repair which ensured I got a good solder joint on the second turn up in the coil by drilling a small hole through the former which the wire is wound around at the right place on the coil. I cut the coil wire and put both cut ends thru' the hole which were dead easy to solder then a piece of wire to the centre of the 239. This allowed for the completed unit to be assembled to the bracket with a better join for the the top plug being made and the bottom end of the coil taken to the bracket and soldered thru' a tiny hole in the bracket instead of being nipped by the screws for the mounting of the cone. I suspect it will be slightly out due to the very small shortening of the coil but will try it tomorrow on the analyzer.

If the overall length hasn't changed much you should need little tuning, when I had set mine up and had it tuned as I required I marked the places with permanent marker so I could take it down and re-erect it with no need to retune.
I hadn't really looked at antenna analysers, I nearly fell off my chair when I saw the cost of a professional ones such as Rig Expert but looking further into it something like the Sark100 looks good at a hobby level and I like the way you can connect it to an Android device or laptop but need to look further into it.

Hey Alan,

Great minds think alike, this is the little fella I've been looking at as well.
also found this little vid on YouTube if you haven't already seen it.

https://www.youtube.com/watch?v=MR1tLQ2D43I

Thomas,
Hope it's of some use to you in setting up the Silver Rod.
73's

Graeme.

This is becoming quite a regular thing I notice Graeme, thank you for leaving the link to the video as I mentioned I am looking into this.

It is looking like an affordable solution as it covers a wide range of frequencies, okay, I realise the professional ones offer a higher degree of accuracy but this is looking great for the hobby side of things plus its "gadget factor" greatly appeals to me too.

I will cast the video to the big screen now and get a good look at it.

Thanks again

Alan

Hi fellas - like you I was put off by the price and opted to try the nano. Horrible to look at and a bit daunting at first but I soon got used to it. Got it 'used' off E-bay for £20 although some new ones were only slightly more expensive. Works a treat for me. I don't go into the Smith chart and things like resistance etc (although I can use the various measuring facilities with the instruction manual next to me). I use it on aerials I have made or prior to putting up a dipole which would have to be taken down to adjust SWR then put up again and so on. I used it on the silver rod and allowing for the fact that it wasn't mounted in it's final position it was showing I was getting 1.3:1 up to 1.7:1 across 27 mhz. I then mounted the aerial in a temporary position, higher (but not as high as I am going to get it) and away from factors which might affect the SWR like my body and the house side. I used an SWR meter to check and found it was 1:1 up to 1.3:1 on the CRT 6900. Leant it to another CBer before he put his aerial up and he had similar experience. Not 100% happy with trusting it but what a time saver...

Brilliant - put my repaired Silver Rod up. Used the marks I'd used before re section lengths and used the analyzer. Showing 1:1.2 @ 27.500. Excellent - put it on the SWR meter and getting 1.2:1 going down to 1:1 at top end of 27mhz but rising to 1.8:1 at bottom end. Have taken it back down with marks emphasised with black sharpie marker. Will lengthen it by a few mils when re-erected. Seems my coil mod does work. Sigma could do with trying it - it certainly takes the strain off the soldered joints!!!

Blue Boy wrote:

Hi fellas - like you I was put off by the price and opted to try the nano. Horrible to look at and a bit daunting at first but I soon got used to it.

Not 100% happy with trusting it but what a time saver...

Antenna analysers are one of those things that once you've had one you'll wonder how you ever got on without them. Saves hours of trundling back to the shack, checking SWR on Ch1 then Ch40, going back, adjusting, going back to the shack, rinse and repeat. They've even saved perfectly good antennas that've been put up which have ended up resonant well outside the range of a CB before being tuned, antennas once we'd have put up, seen it in the red on the SWR meter and not been able to get it out of there and assumed it was duff.

Good to hear your modifications/repairs have done the trick, it is reassuring to hear of others using the budget analysers with positive results too.
I am clearly going to need a better quality SWR meter that covers a range of frequencies and these analysers seem to fit the bill perfectly, up to now I have been quite lucky with antennas but I have had ones that were absolute murder to tune such as a Yagi due to its sheer size, adjusting it on the ground and hoisting it back up again to get a accurate reading.
Now it is time to do my due diligence, look at the different models and set a sensible budget before taking the plunge.
They look incredibly handy and will clearly save time and optimise performance on any antenna project.