SLROC Forum

  Also try 145.6625 stirling repeter GB3FE not a bad one when people are using it 

Thanks guys. Just nice to be able to listen pending the exam.
Thanks again
Geoff

Just be warned CS can be full of Trolls.... and morons

I noticed on Sunday's Green Road Run that a couple of the guys were using VHF radio and decided on channel 21 (I think). Are these sets pretuned to set channels like CB radio??
I havn't got round to fitting mine yet, so I havn't been working through the handbook yet.
Thanks
Geoff 

The answer is "yes", "no", and "maybe". if it is not a synthisised multi-mode set it will probably be continuously tunable although the part of the band that was being used is by gentleman's agreement FM only, and the convention is to use specific frequencies (which relate to channels). A synthisised set can be programmed for different channel steps (spacing) and will appear to step from channel to channel - if these steps are made very small, it will appear to be continuously tuned. They usually display the frequency in use, but some can be programmed by the user to show any chosen text, so that could be a channel number.

On Sunday the quick comments were about channel 21, which is used on Sunday morning at 11:00am for a news broadcast, so we picked 22 instead. These numbers are actually out of date now. The standard spacing for amateur service was formerly 25kHz but it is now 12.5kHz. To accommodate the change all the channels on  most of the bands were renumbered. However, as the centre frequency of the "channel" is what is being refered to by the channel number, that has not changed whether we call it S22 or XYZ916. So we were working on 145.550MHz.

It is all very confusing until you do the RSGB exam course where much will be explained.

73s

Thanks Stuart. I think I get your drift 
Geoff

Another question. I'm going to install my radio in the near future in the 110csw. I'm wondering where on the motor is the best place to mount the aerial. I didn't really want to bore a hole in the middle of the roof. I do have a gutter mount, but where on the gutter is the best place?
Geoff

geoff it doesnt really matter where on the gutter you put it, you can tune the antenna to be accurate if you wish  or have some one check it for you, i would suggest just behind the rear passenger doors, as you are not drilling holes these doors are used less so will damage trapped cables much less. if you haven't bought the cable yet you can get some with a smaller pigtail to go thru the door opening

Thanks for the info. I have got the cable as I bought it at the same time as I bought the aerial. Roll on the course!!
Geoff

You will only do a little about prorogation the course and I don't know if it gets as technical as antenna design. The bit you see sticking up in the air is only one half of your antenna system - the other half is actually your vehicle. That's why a good connection between the screen of the cable and the antenna/mount/bracket/roof is so important.

Where the antenna is mounted considerably affects the signal strength in particular directions. While the antenna can be tuned to give a good electrical balance to the transmitter, that does not alter the shape of the propagation curve. Ideally the centre of a metal roof will give the best all round transmission and reception you can get - near the edge of the roof will reduce the efficiency in a particular direction, on a gutter mount still further reduced. This effect is most noticeable at low frequencies and reduces as the wavelength decreases - at 2m the effect is is quite noticeable. Sometimes having very poor transmission and reception in a particular direction can be useful - if there is interference from a particular direction you can rotate so that the null points in that direction. But it's a right nuisance if driving along and the null points at the repeater you want to use!

Thanks Stuart.
Geoff

you also need to think about separation from other antennas if you have a cb or msa radio as well, hence the suggestion of either side of the roof i have 3 antennas on mine 2 different msa radios either side at the front and the 2m vhf drilled thru the roof in the middle further back, if you want it checked pop along to the club on a wednesday night in d/line i can bring up an analyser
if you want to be really picky about it you can use the same type of mounts for all, if you have a problem you can swap mounts round

Thanks for all the information you're all sending. Much appreciated.
Geoff

Rig is now fitted in the 110. I've clamped the aerial to the gutter at the n/s front, as I'd already filed a hole in the lip for a CB aerial cable to pass above the lip seal.
Not connecting the microphone yet, but I can bring the microphone and aerial to the Green Road Run at Glen Falloch on Sunday if anyone with a licence would like to try it out.
Cheers
Geoff

Good idea.  I'll go look out the meter to check the match first.