[OZAPRS] Narrow Band Radios

[Ray Wells]

Rob,

I use a narrow band Tait T500 series in the car.

For tx I simply increased the deviation to around 4.0khz.

On rx I found the radio performed reasonably well in that it would 
handle 5khz deviation down to about 1uV. For 4.0khz deviation the rx is 
fine down to about 0.5uV but even at signal levels down to 0.25uV the 
busy LED came on to provide the channel busy indicator I needed for the TT3.

My arrangement is satisfactory for an aprs mobile that doesn't need to 
decode packets, just provide a busy indication.

I wouldn't consider using such a radio at a digi location because of the 
poor low signal level rx performance. I was going to hunt around for a 
pair of wide-band crystal filters but see no reason to pursue that 
avenue. I was prepared to place a bit of C across each filter to widen 
(read as totally destroy passband characteristics) the response. Again, 
I won't pursue that avenue.

Ray vk2tv

On 05/02/11 17:07, Rob - VK6LD wrote:
> Hello All,
>
> Apologies if the question has been asked previously.
>
> Just seeing if anyone has any experience using narrow band VHF
> transceivers (12.5khz) for APRS.
>
> I would be interested to know if you had success or failure when using
> as a TX in the mobile or in RX/TX as a digipeater/I-gate.
>
> 73's
>
> Rob...
> VK6LD
>
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