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Old March 20th 10, 08:54 PM posted to rec.radio.amateur.equipment
Stuart Longland VK4MSL Stuart Longland VK4MSL is offline
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First recorded activity by RadioBanter: Feb 2010
Posts: 27
Default Mobile Dual Amateur/CB Radios, do they exist?

On Mar 21, 4:54*am, "Geoffrey S. Mendelson"
wrote:
Stuart Longland VK4MSL wrote:
However, being handhelds, makes them awkward for mobile use -- a
mobile rig would be better, one which combined HF as well would be
ideal.


You need to contact the local licensing authorities and see what is legal..
For example, in the US, what you ask would simply not be illegal, either for
27mHz CB or 464mHz (family radio, what you call UHF CB).

In other parts of the world things are more relaxed, many people use ham
rigs on CB with no problems.


Well... I look at it this way, the CBRS class license dictates certain
rules of engagement. Dedicated CB sets are of course programmed and
hard-wired to ensure most of these are met (there are some rules that
hardware can't stop from being broken; playing music or abusing people
on air for example). So long as a ham set is set up to operate the
same way... I don't see a problem.

Rules as I understand them in Australia:
- HF CB: 6W AM or 12W SSB PEP transmit power around 27MHz. There's a
strict channel spacing to observe -- some of these channels are
reserved for emergency use and other purposes.
- UHF CB: 5W FM between 476.5MHz and 477.5MHz. Again, strict channel
spacing (25kHz). Channels 1-8 channels are reserved for repeater
outputs, but may be used for simplex if no repeater is operating on
those channels. Channel 11 is the calling channel (basically, make
contact then QSY). Channels 31-38 are reserved for repeater inputs,
but may be used for simplex if no repeater is operating there.
Channel 5 and 35 are reserved for emergency use. Channels 22 and 23
are for data communications only -- no voice. Maximum continuous
transmit time: 3 minutes.

It was very easy to get the KG-UVD1Ps to comply with the UHF CB
requirements... Just set the step to 25kHz, work your way through all
40 channels, then for the repeaters -- set it to a +750kHz offset.
The units only do 4W on UHF, and the timeout timer is adjustable -- so
I set it for 150 seconds, which works nicely with the majority of
amateur repeaters too.

Sadly, the things don't have enough memory channels for VHF marine as
well, because the transmitter in them is capable of that too.

Queries:
(1) Does anyone know of rigs that can do this out-of-the-box (like the
Wouxun handhelds)?


There are lots of them that will do the VHF up to 440 mHz (the top if the
70cm band in the US). I have no idea if they will go any higher, but isn't
the UHF CB band 446mHz there? It is here. (I think you said something, but I
trimmed that part of the post before I got here).


Yeah, my old Kenwood used to stop short at 470MHz... that's the
highest I've heard of. Likewise with my FT-897D (which is due for
replacement due to storm damage). So I strongly suspect we'll have to
settle for two radios... one dedicated for UHF CB, and the other to do
everything else.

Note that ham radios do not transmit AM, they transmit double sideband reduce
carrier, i.e. both on USB and LSB at the same time when in AM mode. This usually
works ok on AM receivers, but it may not work on some cheap CB's. It pays to
ask anyone who is doing it if they have a problem.


That is interesting, I would have thought they'd be straight DSB-FC
(regular "AM"). The carrier is adjustable on the FT-897D (and most
likely the '8[15]7 too) so I could bump that up if needed... but this
is one factor I hadn't considered.

Legally may be another issue. Having a transmitter that transmits outside
of the ham bands is illegal in some parts of the world, I have no idea of
what happens in OZ.

Also is it legal for your father to be driving around with a ham radio in
the car, and possible using it (although not on ham frequencies)?


Yep, he's looking at getting an amateur license though at some
point... and if I'm there, we'll be using it as an amateur set. I
suspect if one were to draw attention to themselves, the authorities
will come knocking -- don't give them a reason to show up, and
everything should be okay.