SRD40.68 - the new 49MHz

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Dagnabbit
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SRD40.68 - the new 49MHz

Post by Dagnabbit » 02 Jan 2013, 10:05

As discussed recently here http://www.transmission1.co.uk/forum/vi ... 8&start=15 it seems that the ISM band 40.66-40.7MHz is replacing 49MHz because the 49.82-49.98 allocation is UK-only (having copied the USA many years ago) whereas the newer 40.68 band is European, so more equipment will be made for this new '7m' band and will find its way to our shores.

Looking at various walkie talkie and baby alarm webpages, the manufacturers seem to be using 10kHz steps, some with 5kHz offsets.

40.665
40.67
40.675
40.68
40.685
40.69
40.695

If "40.68" is specified, it may be the name of the band (being 40.68MHz +/-20kHz) rather than the actual spot frequency (harmonically related - 3x - to the 13.56MHz ISM frequency).

The power limit is 10mW (see OFCOM's IR2030), although the band is shared with r/c model control up to 41MHz (or higher in other countries), with 10kHz spaced 40.xx5 channels running 100mW maximum.

With just 40kHz to play with, it should be possible to scan on the typical 12.5-25kHz bandwidth scanner in just 3 memories without missing anything - if you have 6.25 spacing : 40.66875, 40.68125, 40.69375

I'm wondering if baby alarms are more likely to be on other bands these days, leaving these channels actually useful for walkie talkies for a change?
Last edited by Dagnabbit on 02 Jan 2013, 11:29, edited 1 time in total.

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Re: SRD40.68 - the new 49MHz

Post by Dagnabbit » 02 Jan 2013, 11:29

ERC/DEC/(01)03 is the ERC Decision from 12 March 2001 on harmonised frequencies, technical
characteristics and exemption from individual licensing of Non-specific Short Range Devices operating
in the frequency band 40.660 - 40.700 MHz

This was withdrawn effective 9th December 2011 by ECC Decision (11)05 because "the respective ERC Decisions had fulfilled
their mission and did not contain additional information compared with the ERC Recommendation 70-03 or
the EC Decision on SRD (2010/368/EU)"
http://www.erodocdb.dk/Docs/doc98/offic ... EC1105.PDF

(2010/368/EU)
http://www.erodocdb.dk/Docs/doc98/offic ... 0368EU.PDF

Recommendation 70-03
http://www.erodocdb.dk/docs/doc98/offic ... c7003e.pdf
Tromsø 1997, Subsequent amendments 9 October 2012

70-03 states that there is no recommended spacing for 40.66-40.7, but most equipment seems to be on the 5kHz 'raster'.

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Re: SRD40.68 - the new 49MHz

Post by pmr446man » 02 Jan 2013, 20:16

some expensive baby monitors use 2.4ghz dect secure channels
pmr446 king.

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Re: SRD40.68 - the new 49MHz

Post by Bogget » 03 Jan 2013, 12:13

It always balffles me why would you want to monitor a baby if its crying?
we dont even have power in our shed so no where to plug one in anyway.

Bogget :?
Amateur does not have a CH its pronounced "am-a-tore" NOT am-a-chure !

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Re: SRD40.68 - the new 49MHz

Post by superdave » 04 Jan 2013, 20:16

Bogget wrote:It always balffles me why would you want to monitor a baby if its crying?
we dont even have power in our shed so no where to plug one in anyway.

Bogget :?
:lol:

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Re: SRD40.68 - the new 49MHz

Post by pmr446man » 05 Jan 2013, 17:50

Bogget wrote:It always balffles me why would you want to monitor a baby if its crying?
we dont even have power in our shed so no where to plug one in anyway.

Bogget :?
battery operated one most are
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Re: SRD40.68 - the new 49MHz

Post by Bogget » 06 Jan 2013, 22:41

pmr446man wrote:
Bogget wrote:It always balffles me why would you want to monitor a baby if its crying?
we dont even have power in our shed so no where to plug one in anyway.

Bogget :?
battery operated one most are

?

Yes but why?

Why do you want to listen to the baby crying in the shed? they are anoying enough when they are allowed in the house !!!

Bogget :?
Amateur does not have a CH its pronounced "am-a-tore" NOT am-a-chure !

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Re: SRD40.68 - the new 49MHz

Post by Dagnabbit » 07 Jan 2013, 15:20

Reminds me of an old Kenny Everett short sketch -
(dressed as baby, helium voice)
"I cried so much last night my parents put me somewhere else to sleep. You know, that little light does go off when you shut the fridge door!"

So, fancy a 4kW rig on 40.68?
http://www.advanced-energy.com/en/cesar ... ators.html
:D

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Re: SRD40.68 - the new 49MHz

Post by pmr446man » 08 Jan 2013, 11:02

innit
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Re: SRD40.68 - the new 49MHz

Post by bigbloke » 09 Jan 2013, 23:00

just a quick word to the wise...

a number of yaesu radios will appear to tx on 40mhz
but due to the design of the pa and filter switching they are far more likely to go "phut"
if you try to run them on there.

i think the early 817 was one , possibly the 847 too, but dont quote me

regards

BB

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Re: SRD40.68 - the new 49MHz

Post by mayhemicmayhem » 12 Jan 2013, 09:13

The current 817s would tx on 40mhz if freebanded, one would then have the luxury of CTCSS to avoid all the rubbish on there and 49.

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Re: SRD40.68 - the new 49MHz

Post by mayhemicmayhem » 13 Jan 2013, 09:02

Slight correction, it's Digital Code Squelch on the 817s.

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Re: SRD40.68 - the new 49MHz

Post by RogerD » 24 May 2015, 09:08

It's in the news today that the central 10kHz of the 40kHz-wide ISM band is a 'new' 8m band for South Africa, although a comment here begs to differ :
http://www.amateurradio.com/more-news-o ... and-40mhz/

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Re: SRD40.68 - the new 49MHz

Post by hectic » 27 May 2015, 22:35

I wonder if they ever open it up for anything else than "propagation experiments" in SA, even if it has existed for a long time.

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