[UK-CONTEST] AFS

[Ian White GM3SEK]

David Cree wrote:
>
>I do however feel this is a contest which could benefit from a maximum 
>100 watt power limit as that would help reduce the QRM, especially in 
>the SSB section, and as you say it is not a DX Contest and we are not 
>competing with QRO European Stations. If that were the case I would 
>happily switch off my ancient Tokyo HL-2K Linear driven with 20 watts 
>to give 400 out.
>

I'm not so sure about that, having recently done some IMD measurements 
with the SDR-IQ.

At 400W PEP, most linears are running well below their limits and will 
only need about 20-25W PEP of drive from the transceiver. This 
combination will almost certainly create *less* IMD and interference to 
other band users than a barefoot transceiver being thrashed at 100W.

The biggest difference is in far-out IMD - in other words, in overall 
band occupancy.

(By the way, K3 users should specifically AVOID driving a linear with a 
power output of 10-12W on SSB. The main PA drops out below 13W leaving 
only the intermediate PA, which is quite nasty at that power level. 
Increase the power setting to at least 13W so that the main PA comes 
back in; the entire PA chain falls back to much lower drive levels and 
everything cleans up remarkably. This problem doesn't affect CW.)


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek