[Elecraft] bandwidth question of K2

[Chris Waldrup]

Hi Geoff,

Thanks for your input.  I didn't disengage any filters but none of the three 
filters that I had programmed into the uinit were selected.
I do a lot of aeronautical NDB (non directional beacon) hunting and those 
were coming in normally .  I use a homebrew AMRAD LF converter with the IF 
at 7 Mhz.
Last night I decided to try my first attempt at DGPS beacon hunting, and the 
decoder software actually decodes the bit stream and gives information about 
the station.  The local NDB on 350 Khz was strong as usual last night.
I tuned to 7.302 Mhz (302 Khz) to tune what I thought was the semi local 
DGPS beacon in Greensboro.  I was getting ID's from DGPS stations in Holland 
and India, and I got a message that my computer was locked to one in 
Victoria Australia.  The one in Holland is at 302 Khz so I believe this one 
but the one in Australia is somewhere around 318 or 320 Khz.  The PC did 
take an hour to decode the 7 beacons, so I am not sure if something is 
wrong.  The signal I am getting is digital of some nature, so it isn't like 
the NDB's where you can hear CW.  I wasn't sure without any filter manually 
selected by me, how wide a signal I would be able to receive with the K2.

Chris KD4BJ
Raleigh, NC
----- Original Message ----- 
From: "Geoffrey Mackenzie-Kennedy" <gm4esd at btinternet.com>
To: "Chris Waldrup" <kd4pbj at bellsouth.net>
Cc: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Sunday, August 03, 2008 10:52 AM
Subject: Re: [Elecraft] bandwidth question of K2


> Chris,
>
> When you say 'without any filter engaged' am I right in assuming that this 
> means that you have bypassed the KSB2's crystal filter and the K2's IF 
> crystal filter?  If that is the case then the K2's circuits after its TUF 
> mixer would behave in the same way as a simple direct conversion receiver, 
> whose bandwidth would be determined by the two crystal filter just ahead 
> of the product detector and the audio circuits. I don't have my K2 manual 
> here to see if there is anything else.
>
> However I suspect that the reason that you heard a station almost 20 kHz 
> above where you were tuning is that it was being 'heard' by a spurious 
> response of the K2 or your LF converter, or a combination of both. Another 
> possibility is that a spurious response of your LF converter was hearing 
> some oscillator in the K2, but I am assuming that the station 20 kHz up 
> was a real station. If of any help I could run a spurious response check 
> for you later this evening (our time) if you would let me know the LO 
> frequency of your LF converter, the LF input frequency to which you were 
> tuned, and the 40m frequency to which your K2 was tuned when you heard the 
> station 20 kHz above where you were tuned.
>
> 73,
> Geoff
> GM4ESD
>
>
>
>
> ----- Original Message ----- 
> From: "Chris Waldrup" <kd4pbj at bellsouth.net>
> To: <elecraft at mailman.qth.net>
> Sent: Sunday, August 03, 2008 2:24 PM
> Subject: [Elecraft] bandwidth question of K2
>
>
> When I am set to LSB on 40 meters without any filter engaged, what is the 
> bandwidth that I can receive?
> I am using my K2 as a tunable IF for a LF converter that I experiment 
> with, and I heard a station last night that was well above where I was 
> tuning (almost 20 kHz) and I am trying to rationalize that to myself.
>
> Chris
>
>
>