Page: 1 2
simon26OD004
Registered user
Global user
Registered: 07-2009
Posts: 64
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Modified Silver Rod, 5/8th wave Spiderplane
Just thought I'd share with you what I've been playing about with for the last couple of weeks.
Started with a 1/2 wave silver rod, and swopped out the bottom section for a 6 foot 1 inch alli TV pole, I also had to add a thinner section of alli onto the top of the antenna to get up to the 23 foot length I needed.
For the ground planes I wanted to use a square piece of alli plate to mount them onto, but I couldn't find one, so I improvised and used some pine skirting board I had in the shed, and braced it up with some window lintles I found in the loacal builders merchants (lintels cost me 7p each). Got some alli channel from Wickes for about £4 for a 2M length, cut that up and screwed it to the wood, then attached the alli ground planes in the channel by drilling through and using 2 bolts. I could have stuck with the 3-4 foot ground planes, but I wanted 9 foot radials so I extended each radial with wire, and used a bit of rope to tie the wire onto the radial next to it.
The idea was to enable the ground planes to fold upwards by removing one bolt from each of them to make it easy to take portable, but as you can see, the coil ended up larger than I thought it would have....
The coil is made from flat alli strip, also bought from Wickes for £4 for a 2M length. The tap for the coil is about 2 turns in from the bottom. You can see on the bottom right of the pic where the copper wire comes through, on the other side of the wood I've mounted the SO-239 socket, the ground wire also comes through the wood and attaches to one of the radials. The radials are all connected to each other with a short jumper cable. The insulator is made from black pvc waste pipe, with some smaller diameter pipe inside, and the blue plastic tube I stole from one of my kids toys and that fitted snugley over the top. The RF choke is just 6 turns of RG58 quickly knocked up onto a baby milk container (its a cardboard container btw).This is working for now but is not really strong enough, and as you can see the antenna is slightly pissed because of it..
I just popped this up at home for testing/tuning, only had 10W to play with but still managed to work Pat 29SD102 on the beach in Eire, so it seemed to be working pretty well, I stopped playing around when I had a 1MHz bandwidth between 27.215 and 28.335 (1.5:1 swr points) and a nice flat swr around 27.555.
Took it out to the hilltop to have a play tonight, and it worked very well, however with 100W the lowest swr was 1.3:1, so some more fettling needs to be done there. I did manage to work Rich, 26FB456 in Kings Lynn,(thanks Rich) which is a hell of a way from Preston, so it appears to be working well, just needs a little bit more fine tuning and strengthening in places. I might swop out the wood for an alli plate (I have sourced some cheap ones online now) but the benefit of the wood is that the whole antenna is isolated from the mast, and as this will never be a permanent install (just going to use it for /P) I might not bother.
Pic of it on the hilltop tonight, as you can see some inconsiderate bar steward decided to park his van right behind me while I was putting the antenna up, then he buggered off and left his van there !!!
Last edited by simon26OD004, 16/Sep/2009, 10:43 pm
|
|
16/Sep/2009, 10:34 pm
|
Send Email to simon26OD004
Send PM to simon26OD004
|
rich 26fb456
Registered user
Global user
Registered: 07-2009
Posts: 84
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
hi simon! wow thats brilliant!! it worked a treat last night!! a real good contact! youve got to love wicks! i was on my 5/8 wave last night to so vertical to vertical! even better! many thanks for contact hope we can do it again. best 73s rich.
|
|
17/Sep/2009, 4:49 pm
|
Send Email to rich 26fb456
Send PM to rich 26fb456
|
FB220
Registered user
Global user
Registered: 03-2009
Location: Wolverhampton
Posts: 63
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
Brilliant aerial mate, Its good to see the thought process behind every decision. I am in Wolverhampton so I will keep my ears open for you.
--- My personal website and soon to be blog
http://www.wix.com/26fb220/26fb220 |
|
18/Sep/2009, 8:34 pm
|
Send Email to FB220
Send PM to FB220
|
26fb99
Registered user
Global user
Registered: 08-2008
Location: Stoke on Trent North Staffs
Posts: 183
Karma: 3 (+3/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
the things we do for love eh?i reakon Frankenstein used to Dx with one very similar LOL.top work simmo.
---
yaesu FT857d,rmkl500,wilson5000,a99 (thats a real satchel of cack)/2element pubical quad(the BBq).split charger aux battery system.170a truck battery,mfj 941 versatune2
100percent mobile station
laters peeps 73s
Brent 26 Fox Bravo 99
|
|
19/Sep/2009, 10:22 am
|
Send Email to 26fb99
Send PM to 26fb99
|
26FB101
Registered user
Global user
Registered: 04-2009
Location: NW UK
Posts: 166
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
Hi Simon......great pics matey thanks for the upload, your enthusiasm for the great hobby is clear.....well done Simon 
--- 73 & Good DX
 |
|
19/Sep/2009, 10:51 am
|
Send Email to 26FB101
Send PM to 26FB101
|
simon26OD004
Registered user
Global user
Registered: 07-2009
Posts: 64
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
cheers guys,
I had the 1/2 wave SR just sat here for a few years doing nothing, I removed the coil years ago to use as a 1/4 wave for 20M. I wanted to replace the A99 I use on the hiltop for something that had a little bit of gain so this is what I came up with. Can't take credit for the design, it's just ideas pinched from various other sites. I've been playing around with it yesterday and seem to have stronger (and hopefully straighter). Gonna put it up on the hill again later this aft
|
|
19/Sep/2009, 11:20 am
|
Send Email to simon26OD004
Send PM to simon26OD004
|
FB220
Registered user
Global user
Registered: 03-2009
Location: Wolverhampton
Posts: 63
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
Whats the crack with converting an old cb half wave into a quarter wave for 20m. Do you have to ad any groundplanes and what is the easiest way to by pass the coil ?
--- My personal website and soon to be blog
http://www.wix.com/26fb220/26fb220 |
|
19/Sep/2009, 12:40 pm
|
Send Email to FB220
Send PM to FB220
|
simon26OD004
Registered user
Global user
Registered: 07-2009
Posts: 64
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
Only ever done it with a silver rod because the coil is so accessable. You just need to take out the screw that fixes the element to the black plastic at the base of the antenna (the pole will then just slide out), then take the 3 screws out of the bottom next to the so-239 and the black plastic thing will come off and the coil is underneath. I cut the coil out of mine then soldered what was left together, so it just makes a link from the SO-239 to the pole.
Yes you need radials to make it work, add 3 or 4 1/4 wave radials and adjust the length of the antenna just like you would do to SWR it on 11M.
|
|
19/Sep/2009, 9:12 pm
|
Send Email to simon26OD004
Send PM to simon26OD004
|
26fb010
Registered user
Global user
Registered: 01-2009
Location: WEDNESBURY
Posts: 292
Karma: 0 (+0/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
for mine i just ran a long piece of copper wire around the garden (50 foot) it worked good. 4 radials at an angle of 45 degrees would be better though(or 90).... but it is a really good cheap 1/4wave 20m vertical,only 4 feet of the floor !!
|
|
22/Sep/2009, 10:23 pm
|
Send Email to 26fb010
Send PM to 26fb010
|
John193
Registered user
Global user
Registered: 11-2008
Location: South Glos
Posts: 222
Karma: 3 (+3/-0)
|
|
Reply | Quote
|
|
Re: Modified Silver Rod, 5/8th wave Spiderplane
Great effort that, just as future info 8 planes brings the angle down on a 5/8 about 4 degrees and optimum is 16 which gets you a 24 degree brewster angle. So lots of smaller wires are more efficient than a few big fat boys. Coil is great very similiar to a great linear loading coil that, the flat is more efficient than tube for coils due to mass/ surface area relationship. Did you do the math on the dimensions of your coil or trial and error? I'm impressed with it if you make a gamma jumper you can croc clip it on the coil a couple of turns down and work EC bands as a shortened 1/4 too, great stuff.
John193
|
|
24/Sep/2009, 8:11 am
|
Send Email to John193
Send PM to John193
MSN
|
Add a reply
Page: 1 2
Link to us
- Blogs
- Hall of Honour
- Chat
|
You are not logged in (login)
Board's time is: 28/Nov/2009, 10:10 am
|
|
|
