[Elecraft] KSYN3A FAQ

[Edward R Cole]

A couple comments to add to Wayne's:

1.  How many of you have measured the noise floor below 500-KHz?  I 
have used my K3/10 and a SDR-IQ for receiving the 600m band for three 
years.  The SDR-IQ display is in dBm and very accurate.  The receiver 
MDS is -130 to -132 dBm at 500-KHz.  The lowest noise floor I see 
with my inverted-L antenna is -115 dBm.  Often it is -100 or even -90 dBm.

So reality is that sky noise and local noise environment will be your 
receiving limit vs the MDS of the K3.  Those of you who operate on 
160m will recognize what I am saying.  I have not gone below 300-KHz 
so do not know what the noise looks like down there. There is a RGPS 
beacon 3-miles from my house that comes in at -30dBm on 310-KHz.  It 
would be a good propagation beacon for anyone that wants to work me 
on 600m (currently my antenna is down).

Now if you own acreage to put up a Beverage antenna then you may get 
noise low enough to utilize the MDS.  Then there is always adding a 
low noise preamp to improve MDS.

2. Many of us in the ARRL Experimental Group or with experimental 
licenses for operating on 600m utilize bandpass filters to reduce BC 
interference.  I have a Clifton Labs Z10020 Rejection Filter 
(540-1700 KHz) which is limited to 100mw if you plan to transmit thru 
it.  I use it only for receiving.  An Anchorage station (65mi NE) on 
550-KHz normally is seen at -50 dBm, drops into the noise with the 
filter and the broad noise sidebands disappear.
http://www.cliftonlaboratories.com

73, Ed - KL7UW, WD2XSH/45

From: Wayne Burdick <n6kr at elecraft.com>
To: Eric NO3M <no3m at no3m.net>
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] KSYN3A FAQ
Message-ID: <C8964C10-8F25-4626-A216-598B87ADA333 at elecraft.com>
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The KBPF3's lowest-frequency filter has a nominal passband of 0.5-2 
MHz. The rolloff is not particularly steep, but this is the reason 
that the MDS at 250 kHz is -90 dBm, while it's -125 dBm at 450 kHz.

Intermod should rarely be a factor because of the K3's very robust front end.

Those living practically on top of an AM broadcast station typically 
have been through this drill already and have notch filters. If not, 
we can design one for you (you get to build it, though :)

Wayne
N6KR


73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
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