49Mhz anyone?...

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
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Re: 49Mhz anyone?...

Post by radiosification » 28 May 2011, 22:34

curny wrote:My apologies to the moderators for discussing 49mhz in the 446 section...
(Well it is 446, we just lost one of the 4's and the 6 is the wrong way up...)
There isn't really anywhere else it could go. And SRD 860 has been discussed in this section before.
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Re: 49Mhz anyone?...

Post by Adriano9966 » 28 May 2011, 23:14

:) I'm wondering if there is any special criteria for this allocation I mean do sets have to use an integral antenna or need to be type approved in some way?????

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Re: 49Mhz anyone?...

Post by No Rest » 28 May 2011, 23:22

Adriano9966 wrote::) I'm wondering if there is any special criteria for this allocation I mean do sets have to use an integral antenna or need to be type approved in some way?????
My Maxon has a MPT 1336 type approval. MPT 1336 has been superseded by ETSI Standard EN 300 220-1.

http://www.ofcom.org.uk/static/archive/ ... t/mpt3.htm

http://www.etsi.org/deliver/etsi_en/300 ... 20301c.pdf

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Re: 49Mhz anyone?...

Post by wind in the antenna » 28 May 2011, 23:49


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Re: 49Mhz anyone?...

Post by Mikel » 29 May 2011, 10:18

curny wrote:So what easily available (and affordable!) radios are available that can cover these frequencies??

I quite fancy experimenting with 49Mhz.

Curny
Just out of curiosity I checked my Yaesu 857 and it will put out 100 Watts between 33 and 56 megs.

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Re: 49Mhz anyone?...

Post by brianford5mhz » 29 May 2011, 12:51

Latest OFCOM file allocation table lists 49·82-49·98 MHz with 10mW
ERP as being available for general non specific devices.

Now then, Yaesu VX7R's transmit AM/FM down there, and have a
50mW output setting.

50mW into a suitable rubber duck to generate a maximum of 10mW ERP and it would appear to be legit ;-)

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Re: 49Mhz anyone?...

Post by radiosification » 29 May 2011, 12:56

brianford5mhz wrote:Latest OFCOM file allocation table lists 49·82-49·98 MHz with 10mW
ERP as being available for general non specific devices.

Now then, Yaesu VX7R's transmit AM/FM down there, and have a
50mW output setting.

50mW into a suitable rubber duck to generate a maximum of 10mW ERP and it would appear to be legit ;-)
Are you supposed to use am or fm?
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Re: 49Mhz anyone?...

Post by brianford5mhz » 29 May 2011, 13:27

bben95 wrote:
brianford5mhz wrote:Latest OFCOM file allocation table lists 49·82-49·98 MHz with 10mW
ERP as being available for general non specific devices.

Now then, Yaesu VX7R's transmit AM/FM down there, and have a
50mW output setting.

50mW into a suitable rubber duck to generate a maximum of 10mW ERP and it would appear to be legit ;-)
Are you supposed to use am or fm?
You can use anything mode you like, SSB or CW if you wish.

So long as it's 10mW erp and used within the UK only is my interpretation. I took my info from the OFCOM FAT2010 document.

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Re: 49Mhz anyone?...

Post by wind in the antenna » 29 May 2011, 13:49

curny wrote:
The license exempt 49MHz frequencies are:
Channel A - 49.830
Channel B - 49.845
Channel C - 49.860
Channel D - 49.875
Channel E - 49.890


Curny
I'm curious as to why only the bottom 5 channels are used. The allocation is bounded between 49.82 - 49.98 MHz, so there should be 5 more channels to be had. I've only ever once heard a baby bug on one of these channels and that was theoretically a USA import.

Channel F - 49.905
Channel G - 49.920
Channel H - 49.935
Channel I - 49.950
Channel J - 49.965

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Re: 49Mhz anyone?...

Post by curny » 29 May 2011, 15:11

wind in the antenna wrote:
curny wrote:
The license exempt 49MHz frequencies are:
Channel A - 49.830
Channel B - 49.845
Channel C - 49.860
Channel D - 49.875
Channel E - 49.890


Curny
I'm curious as to why only the bottom 5 channels are used. The allocation is bounded between 49.82 - 49.98 MHz, so there should be 5 more channels to be had. I've only ever once heard a baby bug on one of these channels and that was theoretically a USA import.

Channel F - 49.905
Channel G - 49.920
Channel H - 49.935
Channel I - 49.950
Channel J - 49.965
The five channels I listed are the ones I know that (old) UK equipment is used on.
Eg the Maxon and Realistic walkie talkies and handsfree headset walkie talkies
(I've not seen any licence exempt 49MHz stuff with more than 5 channels)
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Re: 49Mhz anyone?...

Post by brianford5mhz » 29 May 2011, 17:02

>I'm curious as to why only the bottom 5 channels are used.

Probably because just about every bit of kit on 49Mhz was xtal controlled.

And xtals are expensive ;-)

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Re: 49Mhz anyone?...

Post by wind in the antenna » 29 May 2011, 17:58

Surely that explains why your average device only has a few channels but not why all manufacturers avoid the top channels. In any case, xtals aren't that expensive if you're buying them in quantities of thousands rather than having them individually cut to resonance.

There's a Radio Shack TRC-512 (21-412) handheld which our friends over the pond on the 49megahertz group have been expanding to 10 channels, even that only has the bottom 5 channels but it's got an LC7150 which only needs addressing to get all 10 channels.

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Re: 49Mhz anyone?...

Post by brianford5mhz » 29 May 2011, 19:28

[quote="wind in the antenna"]In any case, xtals aren't that expensive if you're buying them in quantities of thousands rather than having them individually cut to resonance.quote]

They may be cheaper in bulk, but even then they form a huge amount
of the cost compared to the other components and it's market value.

And what is the market value of a pair of Spaceman toy handhelds ? Not a lot ;-)

Changing the subject slightly, I have fond memories as a kid being given
a pair of these 49Mhz AM walkie talkies.

One transistor regeneratove receivers and a few milliwatts of tx.

I remember having the bright idea at 10 years old of attaching a wire to the
aerial to see if I could improve the range. Something amazing happened !

Because 405 line telly from Crystal Palace was on the air on Band 1, my
crappy receiver brought it in, and Top of the Pops came through on it.

Thrilling for a kid then and I soon learnt the art of DX'ing for life :-)

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Re: 49Mhz anyone?...

Post by wind in the antenna » 29 May 2011, 21:08

Well I guess whatever the reason for the distribution of practically all SRD49 in the UK being confined to the bottom 5 channels, we have the 5 top ones to play around with knowing that we won't be causing anyone any bother. I like the idea of 459.950 being a calling channel as it's reachable on a radio with 25 kHz steps

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Re: 49Mhz anyone?...

Post by bigbloke » 29 May 2011, 21:33

The big problem now with running on 49MHz is not TX power, but local QRM from baby monitors !!

I'll wire the 6m dipole and preamp onto the spec analyser later and show you a plot of 49.6 to 50MHz

Its unusable around here :( and theres a lot of on-site paging in the lower 49 MHz slots too

Cant remember the last time i got a decent DXTV pic on R1 !! :(

regards

BB

(Congrats to whoever resurrected this thread - about a year and 12 days ? that a record ?? ;) )

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