[Elecraft] Why is KX3 phase noise so much less than the K3 ?

Barry LaZar k3ndm at comcast.net
Wed Apr 2 11:56:10 EDT 2014


Phase noise is very important on receive. If your L.O. has a high phase 
noise content, the phase noise will mix with signals away from the L.O. 
and bring those signals into your filter bandwidth as noise. This is 
called reciprocal mixing and is essentially as described below. If you 
want a radio that yields higher signal to noise ratios, everything being 
equal, lower the phase noise.

73,
Barry
K3NDM



On 4/2/2014 11:48 AM, Dave wrote:
> There was some discussion about the effects when on receive as well, I 
> seem to think another manufacturer, not Electraft and not one of the 
> 'big 3' was shown to be quite poor with it's radiated signals even on 
> receive.  Or, did I read the lab reports incorrectly?
>
> Dave (G0DJA)
>
> ----- Original Message ----- Sent: Wednesday, April 02, 2014 3:38 PM
> Subject: Re: [Elecraft] Why is KX3 phase noise so much less than the K3 ?
>
>
>> Like Don said, "not in receive", but in transmit, driving an Alpha 
>> 9500 to the full 1500 out, a close neighbor (about 5 blocks away) was 
>> noticeable on my K3 within 5-10 KHz of his transmit frequency.   That 
>> said, the FTdx5000 was MUCH cleaner than the FT-1000MP he had prior 
>> to obtaining the 5000.  The phase noise & key clicks from the 1000MP 
>> were horrendous but at least his huge signal did not pump the K3's 
>> AGC unless he was within my 400Hz filter passband.
>
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