Friday, Aug 26, 2005 at 19:15
Hi Cruza Ute.
Not an easy question & one that I am unable to precisely answer. I am not really up to date with all the new models on the market today!
I have an old Electrophone TX4000 that has proven to be very good and reliable. It is not the very first batch of these radios that suffered from intermodulation problems. I also have an old Pearce Simpson 2020 UHF which has a remote head and police receive. It is a bit junky in construction and the menue system is a real pain to use. Then there is the old Philips FM620. Never did like the idea of a plastic case and the PAL (TV type) coaxial connector is a poor choice. Otherwise it works OK.
With the new radios on the market today (Amateur as
well as CB), the most important thing is that it performs its primary task
well, so you need to take away the bells and whistles (especially wide band receive) and see how it goes. Also, how easy is it to use - especially for people not familiar with radio things?
Radios with a high gain front end (receiver) may be more prone to suffer from intermodulation (reception of unwanted signals from other frequencies due to front end overload). This is generally worse with high gain antennas and only a problem in the city centres or close to other UHF transmitting sites (eg. Police, Comercial repeaters)
I see that some radios offer CTCSS (continious tone coded squelch system). This does not give you any privacy. It just means that you can't hear any other traffic on the channel unless it is transmitting the same sub-audible tone. The emergency
services use CTCSS to limit interference to there communications. In the amateur service we use it for reducing interference and limiting repeater access for different license grades.
My thought is that Selective calling is best as the new radios will identify the senders Selcall number and it can be used to establish if you are in range (very similar to VKS737
beacon call)
Other issues are the mounting location. Will a remote head be best. Can the display be read at different angles and in
bright sun light? Will over heating be a problem? New radios with litle heat sinking may tend to get hotter than their bigger cousins. Never mount the radio in the direct blast of the car heater!
I noticed that Icom have a new model out that has extras programmable by a computer software interface. The main attraction seems to be storing CB channels in as extra channels and utilising the 25 watt output.
This is not legal for the CBRS but will get you heard further. The problem is that transmitting and receiving work together (if you can hear a 5 watt caller, then they should be able to hear you). With 25 watt out put & most others on 5 watts, you may not be able to hear them! Obviously this would be when pushing the outer limits of the distance possible for 5 watts.
Comercial radios from Philips, Motorolla etc can be modified for the UHF CB band. Note that they are not legal for this use due to the high output power amongst other reasons. They are not as easy to use as a purpose built CB radio. CTCSS is often available but is not user switchable and Selcall may not be an option. Generally options require both hardware and soft ware changes.
Hope this helps. It could be the start of a whole new thread. Probably left out heaps but this is already toooo long!
Cheers Tony VK3CAT
http://www.qsl.net/vk3cat
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