[UK-CONTEST] The first 144MHz UKAC of 2010

[David G3YYD]

Wow a whole 200KHz for so few stations wish it was the same for 80m CC. 
So now and again a bit of splatter, live with it. On 80m CC its not IMD 
splatter but the actual intended RF that causes the QRM - too many 
stations crowded into too little frequency space.

Post Script: Most commercial VHF/UHF rigs have a very very poor receive 
dynamic range of around 70dB add a pre-amp to overcome the poor noise 
factor and usable dynamic range is 60dB or less. So that wideband 
splatter is not solely due to poor transmitters. Although many 
commercial VHF/UHF rigs have poor IMD. Campaign for better rigs rather 
than moan here just as the HF contesters have been doing for decades.

David G3YYD
On 09/01/2010 11:05, Rob Harrison wrote:
> Hi all,
>
> Late but still valid comment I think.
>
> The evening netted 63 qso's, 8 in Europe, all the rest were G, no
> GM,GD,GI,GW or EI. Only one in IO83. Due to lack of EU contacts, did in fact
> spend most of the contest looking for stations in the north west to no
> avail. Either calling CQ, or search&  pounce. This seems to be a trend from
> here, difficult to work anything north of Birmingham, I am screened in the
> general direction of NW. So it's not through lack of trying. I noticed G8APB
> was quite high up the claimed scores, but not a peep from him, or GD8EXI.
> Conditions weren't the best however.
>
> The increase in activity has caused a few problems finding a clear frequency
> to call on. Most of the problems are innocent, stations co-channel just
> don't hear each other initially due to beam headings. So don't get "out of
> the pram" if you find this happening to you, both of you could have been on
> the same frequency for 30 mins or more without interference, before turning
> the beam and discovering " your" frequency was occupied. A case in point.
> I'm in search and pounce mode, hear a weak DL in JN49 calling CQ, it could
> have been a GM/GI, a UK station comes up and says "is the frequency
> occupied" (well done that man) I say "yes", he says "I can't hear anything",
> I say "there's a DL on here calling CQ", he says "oh ok" and goes off to
> find a frequency. All quite innocent and aimiable.
>
> If you keep an eye on the cluster, you'll find some of the "bigger" stations
> will get spotted by non-contesters, or europeans. In chosing your frequency
> to call, it may be prudent to avoid the spotted frequency. At the end of the
> day, 200Khz (144.15 to 144.35) isn't enough for all to have a truly clear
> frequency, so it's compromise.
>
> As for how close is too close, 2.5Khz is reasonable, but unfortunately a lot
> of the modern black boxes aren't too clever on TX, add an amp not set
> up/driven properly and high gain antennas, you start looking at a lot more
> bandwidth you can't use for receive.
>
> 73
>
> Bob G8HGN JO01fo
>
> ----- Original Message -----
> From: "Keith Maton"<g6nhu at me.com>
> To: "UK Contesting"<uk-contest at contesting.com>
> Sent: Tuesday, January 05, 2010 11:27 PM
> Subject: [UK-CONTEST] The first 144MHz UKAC of 2010
>
>
>    
>> That was an interesting evening, very cold in our Martello Tower, every
>> time I breathed out I had to use an ice pick to get through it.  Luckily
>> we didn't get the snow that was forecast but I think a lot of the rest of
>> the country did.
>>
>> One thing I found very frustrating was that I'd been sitting on a
>> frequency just keeping it occupied for around fifteen minutes prior to the
>> start of the contest (I always make a point of spinning the beam the full
>> 360 degrees while doing this to make sure that there's nobody doing the
>> same thing that we're not hearing because they're in a null) with not a
>> peep heard but 30 seconds before the official start time (according to my
>> MSF set watch) someone started calling CQ contest just 2.5 KHz above us
>> forcing me to tune down a couple of k to clear them.  I wish people would
>> take the time to actually listen on the frequency they want to use rather
>> than what appeared to happen, ie just turn the radio on and start shouting
>> without having a good listen around first.
>>
>> Conditions were poor this evening, the highlight was when I suggested one
>> of our operators point the beam towards Scotland and see what we get and
>> after his  second call we did indeed work GM!  No Wales, Ireland or the
>> Channel Isles this evening though.
>>
>> Looking forward to the 70cms contest next week, providing we can find
>> someone brave enough to get the aerial up!
>>
>> 73
>> Keith, G6NHU
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>>      
>
>
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