Ultimate SRD860 and 934 mhz Radios

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Ramjet555
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Ultimate SRD860 and 934 mhz Radios

Post by Ramjet555 » 19 Feb 2012, 01:31

Image

Just finally got the SRD860 Frequencies programmed
into the Kenwood TK-980.
The TK-980 has been modified and programmed for 6.25 Khz channel spacing
and covers the entire four bands continuously from
868.00000 to 870.00000.

It took months of work programming before I finally got it working
the way I wanted. Just tested two radios on 868.00625
and here are the specs.

RF Power Output 15 watts
Spurious Response 60db
Modulation 16K0F3E
FM Noise 45 dB
Audio distortion Less than 3%
Channel Spread In excess of 64 megs typically use
with a 45 mhz offset between TX and RX

These Radios are "conventionally programmed"
to transmit and receive on the same frequency.

They all sorts of wonderful features.
Tone DCS, FleetSync, Call Display, Transpond.
Great for testing. Just set up a unit at a remote
location, key off the code and get a beacon signal
for testing purposes or locating a mobile.

Here is a picture of two TK-980s on 868 megs
and two TK-981 s programmed for 927-933-934 megs
And, the TK-981 can also be programmed for 6.25khz spacing.
(not what it was intended to do)

Band A 868.00625 MHz -> 868.59375 MHz 48 Channels


Band B 868.70625 MHz -> 869.19375 MHz 40 Channels .0125
Band C 869.41250 MHz -> 869.63750 MHz 10 Channels .025
Band C2 869.31250 MHz -> 869.38750 MHz 4 Channels .025
Band D 869.70625 MHz -> 869.99375 MHz 24 Channels .0125

I will have a nice range of suitable antennas shortly.
The best way of shipping these is in a lot, several radios together
with antennas.

If you would like these radios before they go on Ebay drop me a line
or call me on the UK land line (44) 151 808 0041 EXT 888 935 7979
(not after 4:00 PM thanks )

Regards

Ramjet

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SRD860 Guard Frequencies?

Post by Ramjet555 » 19 Feb 2012, 09:22

Can anyone tell me what is between
the SRD860 "Bands"? the radios are capable of 6.25 khz spacing however the
SRD860 spacings go all the way up to 25khz.

Band A is Band A 868.00625 - 868.59375
Band B 868.70625 – 869.19375
Band C 869.41250 – 869.6375
Band D 869.70625 - 869.99375

That leaves some interesting little gaps between the bands that
appear to be for the sole purpose of putting some spectrum between the "bands".
A-B = 868.59375 to 868.70625
B-C = 869.19375 to 869.41250
C-D = 869.6375 to 869.70625

Interestingly, the end of Band D just happens to also end
at the end of the American FCC 800 mhz channels which end at
FCC CH 911 870.000 Mhz.

The first 3 bands do NOT correspond to FCC Channel numbers and European frequencies in Bands A,B & c must be "hacked" to be able to be used.
Band D European channels correspond exactly to FCC Channel numbers.

Ramjet

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Re: Ultimate SRD860 and 934 mhz Radios

Post by RogerD » 27 Feb 2012, 17:44

The bits between the SRD-860 bands are used for Alarm systems - best not to go there!

864-870 is more ideal, but on the higher band Kenwoods if you've only got high 800s and 900s to play with, then I think I've found a suitable gap that you might get away with without interfering with anything.
There's a 'guardband' between GSM-R (railways GSM network 921-925) and GSM (925-960), at 925.000

GSM-R and GSM are 200kHz spaced, GSM-R runs from 921.2-924.8, and GSM starts at 925.2 - so the 200kHz channel 924.9-925.1 is 'free'. Sure, a GSM base station on channel 1 (925.1-925.3, center 925.2) might be actually spilling over a little, but not all the way down to 925.0

If it were me, I'd stick to as close to 925 as possible, maybe 924.9875 or 925.0125 if 12.5kHz offsets are needed, and with the number of experimenters out there I doubt you'd need to QSY :lol:

Staying the low side of 925.0 might be better if possible, as GSM is way more used than GSM-R, and if you're hill-top DX-ing then you're not going to be very close to rail lines - they usually avoid going over hill tops :mrgreen:
- and they beam along the tracks, having little need to cover elsewhere of course.

So if you're contacting other Kenwood owners, with no real reason to choose the old 934 freqs which very definitely are used around the nation, then the 925 area is better. And if you ever get caught, at least it shows you made some effort to cause as little trouble as you could. :ugeek:

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Re: Ultimate SRD860 and 934 mhz Radios

Post by mof000 » 27 Feb 2012, 21:15

Does anybody monitor/use 934mhz nowadays?
I'll pay whatever i think it's worth...:-)

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Re: Ultimate SRD860 and 934 mhz Radios

Post by bigbloke » 01 Mar 2012, 21:52

I wont elaborate on this - but be <<DAMNED CAREFUL>> circa 800-900
stick to the channels you know are safe

regards

BB

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Re: Ultimate SRD860 and 934 mhz Radios

Post by BK » 02 Mar 2012, 20:09

RogerD wrote:Staying the low side of 925.0 might be better if possible, as GSM is way more used than GSM-R, and if you're hill-top DX-ing then you're not going to be very close to rail lines - they usually avoid going over hill tops
A word of caution here; GSM-R is used for signalling, there is a continuous circuit-switched modem connection with the train at all times - if the connection is lost the train will come to a stop. To save money the railways tend to put their base stations on their own land which, as you've pointed out, is not on hills. If you're transmitting on the wrong frequency from a hilltop you could quite easily wipe out a GSM-R base station. I don't imagine you'd be very popular though :lol:

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Re: Ultimate SRD860 and 934 mhz Radios

Post by No Rest » 02 Mar 2012, 23:15

BK wrote:A word of caution here; GSM-R is used for signalling, there is a continuous circuit-switched modem connection with the train at all times - if the connection is lost the train will come to a stop. To save money the railways tend to put their base stations on their own land which, as you've pointed out, is not on hills. If you're transmitting on the wrong frequency from a hilltop you could quite easily wipe out a GSM-R base station. I don't imagine you'd be very popular though :lol:
Trains running late?! No one would notice the difference :lol:

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Re: Ultimate SRD860 and 934 mhz Radios

Post by fez » 03 Mar 2012, 18:14

surely there is anti jamming on GSM-R?

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Re: 900 mhz Radios

Post by Ramjet555 » 20 Mar 2012, 14:53

I'm programming some files for the 900 Mhz Kenwoods. I would greatly appreciate any suggestions for BANDS of frequencies. The radios are capable of Hundreds of channels and my guess is that these radios at first will be used for monitoring and learning what is going on.

I'd like to know more about which freqs such as "railway's GSM-R" etc. Gap freqs etc. PM me if you wish.

Regards

Ramjet


RogerD wrote:The bits between the SRD-860 bands are used for Alarm systems - best not to go there!

864-870 is more ideal, but on the higher band Kenwoods if you've only got high 800s and 900s to play with, then I think I've found a suitable gap that you might get away with without interfering with anything.
There's a 'guardband' between GSM-R (railways GSM network 921-925) and GSM (925-960), at 925.000

GSM-R and GSM are 200kHz spaced, GSM-R runs from 921.2-924.8, and GSM starts at 925.2 - so the 200kHz channel 924.9-925.1 is 'free'. Sure, a GSM base station on channel 1 (925.1-925.3, center 925.2) might be actually spilling over a little, but not all the way down to 925.0

If it were me, I'd stick to as close to 925 as possible, maybe 924.9875 or 925.0125 if 12.5kHz offsets are needed, and with the number of experimenters out there I doubt you'd need to QSY :lol:

Staying the low side of 925.0 might be better if possible, as GSM is way more used than GSM-R, and if you're hill-top DX-ing then you're not going to be very close to rail lines - they usually avoid going over hill tops :mrgreen:
- and they beam along the tracks, having little need to cover elsewhere of course.

So if you're contacting other Kenwood owners, with no real reason to choose the old 934 freqs which very definitely are used around the nation, then the 925 area is better. And if you ever get caught, at least it shows you made some effort to cause as little trouble as you could. :ugeek:

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Re: Ultimate SRD860 and 934 mhz Radios

Post by phillmobile » 02 Feb 2013, 04:36

nice gear forgive me for dribbling on the floor never seen any of those kenwoods 980/981 in uk for sale,i just got some 800 motorola gtx to play with in the 863 to 865 licence exempt bit, they only txrx up to 866

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Re: Ultimate SRD860 and 934 mhz Radios

Post by NL342 » 28 Apr 2015, 19:36

Ramjet,

I am looking for the 933 and 934 mhz version and specific 933.012.500 - 934.987.500 FM with a shift of 25 khz (6,25 khz or 12,5 khz is ok to).
Are those 2 Kenwoods for sale and if yes how much are you asking for them ?
They must be simplex,so no difference in frequency while sending and/or receiving !

Greetings,

Peter.

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Re: Ultimate SRD860 and 934 mhz Radios

Post by albrecht » 12 May 2015, 12:30

A set on 869.706 upwards (24 channels) would be fine for me, safer too.

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Re: Ultimate SRD860 and 934 mhz Radios

Post by ranger » 13 May 2015, 20:30

I read with interest as I don't normally go about 2m!
maybe this is of some use:

https://www.pmse.co.uk/pmse-spectrum.aspx

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Re: Ultimate SRD860 and 934 mhz Radios

Post by LeakyFeeder » 13 May 2015, 21:03

There is a small but very friendly 934 net somewhere round me... Im sure i know who they are as i recognise a couple of voices... Its usually general chat but i have heard em trying dx from the big hill not far from me... Never once heard any of em swear or slag folk... They keep hopping about n seem to have plenty of 'channels' to choose from!

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Re: Ultimate SRD860 and 934 mhz Radios

Post by CA148 » 16 May 2015, 20:49

they must be damned lucky not to have a high powered GSM cellmast nearby drowning out their signals, would love to have the 934 band back again, some great days on that band with some super long distance DX, even into Europe from Liverpool.

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