View previous topic :: View next topic |
Author |
Message |
markymoan *******
Joined: 25 Jun 2005 Posts: 16267 Location: Naughty Step
|
Posted: Thu Apr 09, 2009 23:07 Post subject: |
|
|
Never thought of that one, do you use it as it is or alter it as you wont get much from a lil twig like that, you would atleast need an external loaded coil to get anywhere with 27mhz _________________ |
|
Back to top |
|
|
Google Sponsor
|
Posted: Thu Apr 09, 2009 23:07 Post subject: Google Ads keep this community free to join! |
|
|
|
|
Back to top |
|
|
rallymarshall *******
Joined: 04 Mar 2007 Posts: 1728 Location: somewere thereabouts
|
Posted: Fri Apr 10, 2009 10:38 Post subject: |
|
|
i realy need to get my rig sorted, can hardly pick up anything on 27mhz, having said that i can hardly pick up anything on the other bands either
doesn't matter what aerial i use and no difference on the dv mount or the mag mount, neighbour gave me a twin rig set up cable so i mite get another dv mount and put them both on the rear diffuser thing
i would have thought id get something with my rig http://www.kcb.co.uk/10metre/magnum_257.htm
very rarely gets left in the trooper tho, occasionally lives on the tractor _________________ atb kevin
65 vauxhall mokka 1.6cdti 4x4 se
66 vauxhall corsa vxr |
|
Back to top |
|
|
c8 sdd **
Joined: 02 Dec 2008 Posts: 58 Location: Cambridgeshire
|
Posted: Fri Apr 10, 2009 21:14 Post subject: |
|
|
markymoan wrote: |
Never thought of that one, do you use it as it is or alter it as you wont get much from a lil twig like that, you would atleast need an external loaded coil to get anywhere with 27mhz |
Without getting too technical, the lower the frequency ... the longer the antenna.
A mobile phone on 2400mhz need about 8mm.
A police tetra radio on 470mhz needs a whip on the police-cars roof of about 35cm.
The correct length for listening to radio one on 99.7mhz is about 1500mm.
The correct length for a 27mhz cb radio is 6500mm!!
You ain't going to have 6.5 meters on your roof, so the coil simple compresses 3/4 of that into a compact package.
(A correctly designed base loading coil can actually increase antenna efficiency).
With regards to the rear window demister as an antenna, casically you need whats known as an antenna
tuning unit. (Atu).
Its a box that sits between the rig and the antenna and with carefull adjustment it "fools" the rig into seeing a minimal level of reflected energy, meaning the rig is happy to throw
the whole 4 watts out of its rf socket.
Regardless ... a rear window demister is incredibly *beep* for any type of radio use.
If you want range, stick with a whippy thing on the roof. If you just want to talk to the guy in front on a greenlane/off-road course, its fine!!! _________________ .
1992 Isuzu 3.1td swb ... now being prepped for mot ... what a disaster!!!
1988 BMW 730 ise auto ... just passed another mot, 8 straight passes in a row!!!
|
|
Back to top |
|
|
markymoan *******
Joined: 25 Jun 2005 Posts: 16267 Location: Naughty Step
|
Posted: Sat Apr 11, 2009 3:24 Post subject: |
|
|
mmmm atu, I think we used to call that a matcher in the old days. _________________ |
|
Back to top |
|
|
c8 sdd **
Joined: 02 Dec 2008 Posts: 58 Location: Cambridgeshire
|
Posted: Sat Apr 11, 2009 17:18 Post subject: |
|
|
markymoan wrote: |
mmmm atu, I think we used to call that a matcher in the old days. |
Its a thing that leaks smoke in your bedroom when you accidently put 400 watts into it at 3.650mhz when the
other side is connected to a 70mhz antenna.
Moral of the story ... they have limitations!! _________________ .
1992 Isuzu 3.1td swb ... now being prepped for mot ... what a disaster!!!
1988 BMW 730 ise auto ... just passed another mot, 8 straight passes in a row!!!
|
|
Back to top |
|
|
c8 sdd **
Joined: 02 Dec 2008 Posts: 58 Location: Cambridgeshire
|
Posted: Sat Apr 11, 2009 17:21 Post subject: |
|
|
Just out of interest .... here's a piccy of my old "radio shack" setup.
This lot gave me transmission capability on all of the permitted amateur radio allocations from 1.6mhz through to 433 mhz.
If you look carefully you'll see a maycomm EM27 that i modified to cover from 26.7mhz to 28 mhz, with a heady 6 watts output.
(Curiously, the maycomm caused more tv interference than any of the other stuff ... probably because it didn't have any output filtering).
_________________ .
1992 Isuzu 3.1td swb ... now being prepped for mot ... what a disaster!!!
1988 BMW 730 ise auto ... just passed another mot, 8 straight passes in a row!!!
|
|
Back to top |
|
|
markymoan *******
Joined: 25 Jun 2005 Posts: 16267 Location: Naughty Step
|
Posted: Sat Apr 11, 2009 17:40 Post subject: |
|
|
What the
Are you KGB _________________ |
|
Back to top |
|
|
rallymarshall *******
Joined: 04 Mar 2007 Posts: 1728 Location: somewere thereabouts
|
Posted: Sat Apr 11, 2009 21:07 Post subject: |
|
|
markymoan wrote: |
What the
Are you KGB |
dont you mean the C IA
they reckon they always listeniing _________________ atb kevin
65 vauxhall mokka 1.6cdti 4x4 se
66 vauxhall corsa vxr |
|
Back to top |
|
|
scj103 Lifetime member
Joined: 07 Feb 2009 Posts: 509 Location: Norfolk (watton)
|
Posted: Tue Apr 28, 2009 21:42 Post subject: |
|
|
Dangerous territory here, the men in white coats will be along here soon...have yet to fit my maycom em27 to my troop...
Anyone got a Rexon RL402 lying around...they were fantastic 70cms transceivers... had mine at uni, though havnt done anything on that front for nearly 10 years...like others, got fed up with the random gibberish instead of using it for worthwhile purposes...
Still, once the cb is in, might have to attach a 6.5m whip to the roof
See if the missus notices... _________________ '98S reg Irish Trooper 3.0DT Citation (LWB 7seat)
65 plate Octavia Scout
'83 A reg 2CV... |
|
Back to top |
|
|
billy.mc **
Joined: 28 Jul 2008 Posts: 101 Location: Denton, Manchester
|
Posted: Tue May 26, 2009 11:42 Post subject: |
|
|
i'm having probs with my CB, just got a brandspank midland minor with a full size whip from maplin & drill mountd my springer in the roof @ the rear but i only get 500 yrds if i'm lucky, everything is fitted nice n tight plus the springer is pretuned so not bothered with a swr! anyone noticed a grounding prob with the roof on these?? _________________
RIP '92 LWB 2.3Fronty, RIP '92 LWB 3.1cit, RIP '91 LWB 3.1Cit, RIP '96 LWB 3.1Cit, Dont ASK '97 4.0 Cherokee ;-(, NEW '93 3.2V6 Auto HORN!!! |
|
Back to top |
|
|
scj103 Lifetime member
Joined: 07 Feb 2009 Posts: 509 Location: Norfolk (watton)
|
Posted: Tue May 26, 2009 12:15 Post subject: |
|
|
Nope, grounding on the roof of mine is fantastic...got it grouding lots of things nicely...including my lightbar (40A)!!!!! _________________ '98S reg Irish Trooper 3.0DT Citation (LWB 7seat)
65 plate Octavia Scout
'83 A reg 2CV... |
|
Back to top |
|
|
billy.mc **
Joined: 28 Jul 2008 Posts: 101 Location: Denton, Manchester
|
Posted: Tue May 26, 2009 13:06 Post subject: |
|
|
cheers i'll get to the bottom of it soon, was embarracing sunday when i had mentioned a day out & no one could get me once they were there!! _________________
RIP '92 LWB 2.3Fronty, RIP '92 LWB 3.1cit, RIP '91 LWB 3.1Cit, RIP '96 LWB 3.1Cit, Dont ASK '97 4.0 Cherokee ;-(, NEW '93 3.2V6 Auto HORN!!! |
|
Back to top |
|
|
markymoan *******
Joined: 25 Jun 2005 Posts: 16267 Location: Naughty Step
|
Posted: Tue May 26, 2009 13:46 Post subject: |
|
|
I had a problem with a maplin springer, the whip didnt have contact with the coil, I took the whip out and gave both contacts a clean. _________________ |
|
Back to top |
|
|
billy.mc **
Joined: 28 Jul 2008 Posts: 101 Location: Denton, Manchester
|
Posted: Tue May 26, 2009 14:38 Post subject: |
|
|
cheers bud will have a look after _________________
RIP '92 LWB 2.3Fronty, RIP '92 LWB 3.1cit, RIP '91 LWB 3.1Cit, RIP '96 LWB 3.1Cit, Dont ASK '97 4.0 Cherokee ;-(, NEW '93 3.2V6 Auto HORN!!! |
|
Back to top |
|
|
Steam Hound ****
Joined: 22 Feb 2005 Posts: 422 Location: Suffolk
|
Posted: Fri Jun 19, 2009 22:19 Post subject: |
|
|
nice gear in the picture |
|
Back to top |
|
|
|