Ad blocker detected: Our website is made possible by displaying online advertisements to our visitors. Please consider supporting us by disabling your ad blocker on our website.
A forum for the discussion of matters of a technical nature. All such activities are undertaken at the readers discretion and own risk. If you don't know what you are doing, don't blame us if it all goes wrong!
Dummy load and zetagi pwr/swr / mod. trust me wasnt getting past 5w no matter what obviously they turned it down to match UK legal pwr even on ssb. Which was useless as i was getting 1 watt average talk power.
First shout i got a call back and a friend of mine who lives a about 15 mile away said it sounds great, where as before i was'nt even moving his S-meter unless he had the pre amp on or i had my linear on.
I've checked peak stability using a sound file/ tone it will peak to 15w max.
Stock Multi-Norm ETSI EN STD are 2.00khz max deviation
Why,because IF filters lot more narrower!
Plus 95% based on 10khz channel spacing
Where UK older MPT specs had wider filters,FM decriminator audio set different ly in audio gain recovery and transmit deviation is set higher 2.20khz on 2khz testone,peak deviation max 2.50khz.
Why don't they set them higher at factory?
Because MPT UK 27/81 is now a defunct specification and longer applies to new Multi-Norm radios.
Why don't cb manufacturers put a feature to switch deviation between EU and UK?
I have asked and requested this many times but it seems falls on deaf ears!
So for ref
EU/FCC & ETSI
Mic gain max
2.00khz max Dev
60%=1.25khz Dev
Ctcss 300Hz Dev
Old MPT 27/81 sets
Mic gain max
2.20khz max (1khz test tone ,15khz lpf Dev meter)
Ctcss 300hz
New Multi-Norm sets to new Multi-Norm cb on UK won't matter ,it's only when going new to older cb the problem happen.
Best way slightly tweak up FM deviation
They are other ways to resolve this but it's a bit more in-depth to convert older MPT radio to newer ETSI specs so no issues us some technical benifits.
455HT filter fit tighter bandwidth filter.
Increase resistor value in FM descriminator coil or resonator to
Coil 48-68kohms or
455khz Resonator 3k8-4k2
Increase recovered audio at 60% deviation,as we going from UK old 1.50khz to new EU specs 1.25khz.
Inject 1khz test tone,mic gain max
Set FM deviation 2.00khz max (15khz lpf on deviation meter setting)
Check CT tone set 300hz if on set .
Better SINAD and Rx sensitivity
Correct recovered audio level on Multi-norms sets at lower deviation levels
Better adjacent channel rejection with new IF filter 455HT .
I've tried this on a older UK Uniden 27/81 set works fab ,fantastic sensitivity on Rx now too and completely inter-changeable
With UK band on another Multi-Norm cb radio un-touched.
