Ok if you have a radio, lets say a Garmin, and you set it to 8.33 mode then when
you select an 833 channel the appropriate frequency and bandwidth is selected.
If you step though the channels/frequencies it will also allow selection of
an 25khz frequency and the radio will automatically select the 25khz frequency
and bandwidth to suit. You do not have to go into the menu system to set it
back to the 25KHz mode.
There will be no difference in quality as speech is confined to 300 to 3KHz
regardless
which is well within the 8.33 bandwidth. Im sorry those who claim there
is a difference in speech quality or signal strength are misleading or possible
have been using poorly maintained radios.
There is an issue with ICAO radios in that their first attempt at an 833 radio
resulted in it not been able to select 25 KHz frequencies when configured in the
8.33 mode so you could not for example select 121.5, which will remain a 25KHz
frequency for technical reasons. There is however a firmware upgrade available,
free I believe, which fixes this problem and then allows you to step through
833 and 25KHz channels and frequencies as appropriate without switching between
the two operating modes, or setting them up in the memory which is a workaround.
The radio takes care of the appropriate tuning of the circuits to suit.
Alan Burrill
Sent from my iPad
> On 25 Jul 2019, at 20:40, David Lewendon <davidlewendon@me.com> wrote:
>
>
> Thanks, only how i understood from the previous message was that using 8.33
> for
25khz might result in a weaker reception.
>
> David
>
> G-FITY
>
>> On 25 Jul 2019, at 20:30, Groups <groups@thegoddards.com> wrote:
>>
>>
>> When set to 8.33 you select channel numbers and not frequency:
>> Channel 134.100 is 134.1 MHz 25 KHz
>> Channel 134.105 is 134.1 MHz 8.33 KHz
>>
>> You do not need to set your radio to 25KHz mode access the original 25KHz
>> frequencies,
just dial in the appropriate channel number and it swaps from 25 to
8.33 spacing automatically.
>>
>> Vince
>> G-BWUP & G-BJAF
>> Europa Cub
>>
>> Sent from my iPad
>>
>>> On 25 Jul 2019, at 17:18, JonathanMilbank <jdmilbank@yahoo.co.uk> wrote:
>>>
>>>
>>> Hi Europa48,
>>>
>>> The short answer is probably "yes", based only on our local situation where
as soon as we leave our airfield 8.33 channel, we must talk to Aberdeen Offshore
Radar on frequency 134.1 MHz which is on the original 25 KHz spacing. My Icom
radio is quite difficult to switch between 8.33 and 25 KHz modes, causing
too much distraction while attempting to do so.
>>>
>>> Therefore I have Aberdeen Radar 134.1 MHz permanently in the list of
>>> memories,
which causes the radio automatically to operate on 25 KHz mode only when
accessing
a specific memory. If I then choose to turn the two selection knobs for
some reason, they resume functioning in 8.33 directly without any input from
me.
>>>
>>> If I were to change the radio to 25 KHz mode, then the selection knobs would
operate in 25 KHz steps, which would be unwise because almost all airfields
and airports have gone over to 8.33 channels. The only reason that Aberdeen
Offshore
remains on 134.1 MHz is because it's Rebro, having 3 additional satellite
rebroadcasting stations on such remote locations as offshore platforms. To
change all that would be a considerable challenge.
>>>
>>> I'm not an expert in this field, but I suggest that you should leave your
>>> radio
set in 8.33 mode and put any old 25 KHz frequencies into memory.
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=490529#490529
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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