[Elecraft] KX3 - Does It need Preamp for 6M?

[Edward R Cole]

Wayne cites the MDS is -140 dBm with the KX3 preamp set to 
30-dB.  That is excellent and all that is needed for terrestrial 6m 
operation.

I would dispute the advantage of mast mounting a preamp on 6m.  I 
recently showed a reader what the effect would be using a 0.5 dBNF 
25-dB gain GasFet preamp at the antenna vs at the radio in an eme 
operation.  Sky noise temperature runs > 2000K at 6m even for quiet 
locations with the result of only increasing MDS by a tenth of a dB 
when the preamp is located at/near the antenna.  Use of low-loss coax 
like Belden-9913 or Times LMR-400 is sufficient to run 6m preamp at the radio.

On frequencies 2m-and-up the sky noise situation changes this to 
where there is marked improvement locating a preamp at the antenna 
(and essential for weak-signal work like eme).  I will be running 
800-1000w on 6m-eme later this year (after the yagi is mounted on a 
new tower) and will run my 6m GasFet preamp at the K3 using the RX input.

73, Ed - KL7UW
http://www.kl7uw.com
dubususa at gmail.com
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