[UK-CONTEST] RRTC

[David, G3YYD]

Danny

The filtering also applies to the TX to remove noise and spurious.

I have been thinking about it and I could even now with my current SO2R 
setup using W3NQN filtering do same antenna working on adjacent bands. I 
would need to add to the filters a relay and a resistor. The resistor 
would go between the filter and the antenna on receive so the receive 
filter does not cause problems for the TX VSWR. The RX would be OK as HF 
RXs have excess sensitivity so could loose 20dB of signal due to the 
resistor and still get a good signal to noise ratio. The relay would 
remove the resistor for TX. Alternative would be to use a directional 
coupler, but resistor is simple and cheap.

I have no noise or overload problems from the current separate antenna 
working with a worse case loss between antennas of 25dB. I know Bob 
5B4AGN has a similar filtering set up with antenna separation in one 
case of 12dB without problems. I suspect it is not as difficult as one 
may think after all repeater stations on 2M do it with 600KHz separation 
at 144MHz which is the same as 60KHz at 14MHz - mind you the cavities 
would need to be the size of a garage!

David G3YYD

Danny Higgins wrote:
> I don't think it is all down to filter technology.  The broadband 
> noise from a transmitter on the same co-ax will get through any 
> filter, unless it is somehow cancelled out.
>
> Danny, G3XVR
>
> David, G3YYD wrote:
>> Roger
>>
>> Any hints on what the filtering technoogy used?
>>
>> David G3YYD
>>
>> Roger G3SXW wrote:
>>  
>>> Dear UK-Contest,
>>> I observed Russian Radio Team Contest as preparation for WRTC-2010. 
>>> It was held just outside Moscow with 18 two-man teams, and was the 
>>> 18th straight year that it has been held. Field Day style, all 
>>> stations within a few miles of each other (but minimum separation of 
>>> 500 metres) on flat grass-lands. Identical antennas: tribander and 
>>> 40m Vee at 35 feet. Eight-hour multi-mode contest, changing 
>>> call-sign and exchange each two hours. Full-time Referee monitoring 
>>> each Team. The winner RW3QC/RN3QO made 1,532 QSOs, an average of 
>>> over 190 per hour throughout.
>>>
>>> Set-ups and operating were extremely impressive: two radios, two 
>>> ops, often one CQ, the other S&P, with lock-out to prevent both TX 
>>> at the same time. All the leading four teams used a filtering system 
>>> allowing TX on one radio and RX on the other radio at the same time 
>>> ***on the same antenna/coax***. Cor!
>>>
>>> The log-checking data-base benefited from some 600 external logs 
>>> e-mailed within four hours and the whole adjudication process was 
>>> finished some eight hours after the end of the contest, with the 
>>> award ceremonies the following morning.
>>>
>>> It was an enjoyable weekend (language is a problem though). WRTC 
>>> competitors next year will be well cared-for but will have some 
>>> difficulty beating these super-slick Russian competitors!
>>> 73 de Roger/G3SXW.
>>> _______________________________________________
>>> UK-Contest mailing list
>>> UK-Contest at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/uk-contest
>>>       
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