Transmission1

As some of you are aware, many of the 'big 3' Yaesu, Icom, Kenwood radios have a facility to operate on the USA 1.25m band (222MHz).
Most of the rigs bought in the UK are 'blocked' from TX on this band, but I've heard tell that some people are 'opening up' their radio to freeband (Heaven forbid ), thereby enabling TX here.

Just curious as to whether there is any activity on the 220MHz band in the UK.

As far as I know, the DAB broadcasts run right the way thru this allocation, so maybe it would be a waste of time, but there is a lot of kit out there, able to be used around those frequencies, and I KNOW that someone will have been 'curious' to see what the range is of their shiny new VX-7r is, with 1.5W on 222.

Is it just a sea of digital noise on 222, or is it usable, and if so, any results?

Seems that not many 'nosey' people would be scanning around there to intercept your transmission.

Alinco make a dedicated 220MHz , 25W mobile for this range:

http://www.eham.net/reviews/detail/1404

Just interested, that's all.

I guess it just depends whether you have a multiplex in your area. I'm supposed to have a NOW Digital Ltd. MPX on 220.352000 MHz which as a 75kHz carrier I'd expect to see as a reasonably strong signal. The whole of 220MHz seems reasonably quiet here in Brighton however on the IC-R7000 on all modes and bandwidths. I'm not sure if that means there is no OFDM here but it appears usable none the less.

As a footnote here, a number of ex-PBR band II 'trunkies' can be programmed to here in conventional mode 8K50F3E

I used to have a five element Triax up for DAB DX using a Psion Wavefinder and I do remember monitoring signal strengths on the Icom. From here in Mid Sussex I could get either the Hants or Kent MUXs on 11C both at S9 depending on the beam heading.

220MHZ is military air band, Cardiff airport's military tower frequency is around about 225MHz.

Having done a bit of reading, it turns out that the band is 222-225MHz

Block 11d centres on 222.064000 MHz
Block 12b centres on 225.648000 MHz

These just show as lumps of noise on the IC-R7000 in FM at broadcast bandwidth. The OFDM carrier can be heard at the fringes with an analogue receiver.

Here's the interesting bit, a Band III DAB MUX is 1.537 MHz wide, which implies that there is an unused 2.047MHz wide gap between 222.8325 MHz and 224.8795 MHz unless I've missed something (it wouldn't be the first time).

A bit late to the thread but you'll easily see why 220MHz is a non-starter in the UK !!
The image shows an off-air trace taken this morning from my home into a conical VHF dipole:

centred on 225.000MHz
span set to 10MHz bandwidth
and not attenuated

that peak signal figure is accurate by the way ! -28 dBm AIR PATH !! from the local DAB TX
which is about a mile-and-a bit away from me. MASSIVE signals

to put that into perspective, If I were to place the antenna of a GSM mobile phone against the antenna combiner of the GSM base station I would reasonably expect to see -45dBm...which is a fair old signal!

But this is some 17dB above that

BTW dont assume that because you cant see anything of consequence between 222 and 224 MHz in my trace that it is unused and therefore ripe for freebanding . Its just not used around here


Regards

BB

GW0DIV wrote:220MHZ is military air band, Cardiff airport's military tower frequency is around about 225MHz.

Really? I thought that cardiff UHF simulcast with St Athan was 251.375 (source milscan.nl / SWAG)

havent checked in a while though

or were you refereing to St Athan Tower ? (231.800 if memory serves)


regards

BB

I don't know what the selectivity is like in DAB radios, but I fear that pirate transmissions, even in the "guardbands" between channels, could wipe out DAB radio for many listeners. I'd hate to see it become such a problem that there would be a nasty crackdown upon wideband TX radios, etc.
Be careful where you play!

Is there any freq thats is safe from pirate activity nowadays ??!! have to say guys completely agrea with the above poster be very careful with tx on anything out off the usual pirate bands just because there is not a lot off prosecutions over the last few years for this sort off thing would well imagine anything out off the ordinary ie. 220mhz tx would certainly raise a few eyebrows.

could be wrong but just be careful above all have fun

Anyone want to buy some Band III Tait T2040s and Orca handies?

No thanks. I'm awash with Kenwoods

715s? I had two of them. Nokiaman has them now.

I'm not an expert or rig doctor but I have 2x tait 2000 on 235 -175 MHz BAND 4. I looked online for any info and came across this thread because I have been wondering if these radios had any use at all.

Let me think.... I could put them on the 1.25 M band and sell them to some Americans maybe? probably not worth the postage I don't know.

I can change them to BAND 3 136 - 174 MHz and they will take 2M frequencies but will need some realigning and I don't know if those radios RX/TX could align down to 145 MHz as they are BAND 4 radios. I sure somebody on here would be able to say whether or not they would work on 145MHz?

145 MHz might be to far down to align correctly. If that is the case then there is always putting them on UK light channels 169MHz/173MHz isn't that far off and they should work without problems in BAND 3.

Edited today. Yep I could not get them aligned for 145MHz they wouldn't have worked very well without modifications so I put them back on BAND 4... 175 - 235 MHz

BAND 4 it let me enter 169.3125 MHz & 173.0500 MHz 173.0625 MHz 173.0875 MHz even though they are below 175 MHz. Both radios aligned nicely and can be used on UK Simple Light VHF back to back.

It would be interesting to see what the RX sensitivity is like. TX may be a bit all over the place but thats for 2 meters but for 169/ 173 MHz it be fine.

I've dreamed about having the 1.25 meter band in the UK. It could be done, You'll only need 4 empty frequencies in that range, then ask if one of the disused SATCOM satellites could be used on the 1.25 meter band as a repeater and maybe have another channel linked to the internet for America. A local calling channel and one simplex channel to move to.