[OZAPRS] 6M Radio

Scott Allister Keith Habgood webster01 at optusnet.com.au
Thu Nov 23 19:30:47 AEDT 2017


Challenge accepted Glen!!

As soon as you get 6m repeater going I’m going to see if I can use voice on it from Dubbo!!!!!!!



Scott 
VK2UBQ


> On 18 Nov 2017, at 9:30 pm, Glen English VK1XX <glenlist at pacificmedia.com.au> wrote:
> 
> Robert,  what sort of radio do you have in mind for the job ?
> 
> I'm in canberra so out of mobile range....
> 
> One of these days I'll get the 6m repeater up and going at Ginini, The
> duplexor is on site...
> 
> I'll be sure it can pass 1200 bps packet with regeneration facility...
> after all no one will ever use it for voice.
> 
> -glen
> 
> 
> On 18/11/2017 4:52 PM, Robert wrote:
>> Thanks Glen.
>> 
>> Rather have a separate 6m tx sitting away in the vehicle doing its stuff, insteat of a hf/6m unit been wasted.
>> 
>> Robert
>> 
>> -----Original Message-----
>> From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of vk4tec at tech-software.net
>> Sent: Saturday, 18 November 2017 4:08 PM
>> To: 'Australian APRS Users' <ozaprs at aprs.net.au>
>> Subject: Re: [OZAPRS] 6M Radio
>> 
>> http://www.wia.org.au/members/bandplans/data/documents/Australian%20Band%20Plans%20100404.pdf
>> 
>> Google
>> 
>> 
>> 
>> -----Original Message-----
>> From: OZAPRS [mailto:ozaprs-bounces at aprs.net.au] On Behalf Of Glen English VK1XX
>> Sent: Saturday, 18 November 2017 2:48 PM
>> To: ozaprs at aprs.net.au
>> Subject: Re: [OZAPRS] 6M Radio
>> 
>> Hi Robert
>> 
>> my 2$ worth : a primer on 6m performance and what to expect. it is certainly a curiosity and there is much to be learned from playing about with it.
>> 
>> 1) mobile performance on 6m is in the toilet, unless you work very hard on your vehicle antenna. This is due to low height above ground producing near antenna fresnel blockage, higher radiation angles and higher ground losses. so you need power to overcome antenna efficiency -  100W.
>> But most HF/6m radios do 100W .
>> 
>> 2) if comparing to 2m, 6m has only advantage in very hilly, and multiple hilly terrain, many hills in the way. 
>> 
>> 2.5) 6m also has a advantage with regard to heavy foliage forest attenuation. (Less)
>> 
>> 3) 6m has less picket fencing, and the short delay multipath (due to nearby scatterers) is not as deep as the reflections are not as strong or coherent.- advantage.
>> 
>> 4) galactic noise (alone) is about 10dB more than at 2m. The only 'advantage' of this that sloppier systems will work 'cause they are not as affected by coax losses and high recv noise figures.
>> 
>> 5) 6m base station antennas need to be ~ 1.7x the height  of a 2m antenna to get the same takeoff.  People make the mistake of NOT putting the lowest frequency antenna at the top of the mast.
>> 
>> So, if the base stations are ideal, and there are multiple obstructions in a path, 6m signals will be stronger than 2m on long , difficult paths that are diffraction paths (not troposcatter) paths.  The signals are stronger but the noise floor of 6m masks the signals, so you got to be prepared to work at narrower bandwidths to take advantage of it. Once the path becomes a troposcatter path, you might well be better off on 2m.
>> 
>> So, apart from the curiosity which is 6m FM, I think that 300 baud 6m SSB HF packet would be a better utility, because it has a roughly 10dB advantage on 1200 bps AFSK FM . maybe 13 dB depending on the demod...
>> 
>> Mobile footprints of 6m repeaters are generally much smaller than 2m repeaters at same sites. This is due to alot of things but many of the above.
>> 
>> Troposcatter is in the toilet, but ionscatter is of interest (900-1500km).
>> 
>> -glen
>> 
>> 
>> 
>> Having said all that,
>> On 18/11/2017 2:48 PM, Robert wrote:
>>> Hi All.
>>> 
>>> Just thinking about playing around with 6M APRS.
>>> 
>>> So my questions are.
>>> 
>>> What is the freq that is used in Aust.
>>> What would be a good radio to use, or modify to use on 6m What TNC 
>>> details/config is needed.
>>> 
>>> Thanks in Advance.
>>> 
>>> Robert
>>> VK2KGV
>>> 
>>> _______________________________________________
>>> OZAPRS mailing list
>>> OZAPRS at aprs.net.au
>>> http://lists.aprs.net.au/mailman/listinfo/ozaprs
>> 
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