472KHz/500KHz

[Dominic Baines]

Anyone tried the K3 option with a KX3 on 472/500KHz yet?

http://www.elecraft.com/TechNotes/k3qtx_v2_pa3cw.pdf

Will be trying but interested to hear anyone's success/failure stories.

72

Dom
M1KTA

[Matt Maguire]

Did you read in that article how a KXV3 module is used in the K3 to bypass the high pass filtering used to protect the T/R PIN diodes? The KX3 has the same filtering, but no possibility for a KXV3 module. Therefore, the KX3 is not really usable below around 1500kHz.

If you want to get onto the 600m band with a KX3, you'll need to look at building a transverter.

73, Matt VK2ACL



On 04/09/2012, at 6:59 PM, Dominic Baines <[hidden email]> wrote:

> Anyone tried the K3 option with a KX3 on 472/500KHz yet?
>
> http://www.elecraft.com/TechNotes/k3qtx_v2_pa3cw.pdf
>
> Will be trying but interested to hear anyone's success/failure stories.
>
> 72
>
> Dom
> M1KTA
>
>
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/472KHz-500KHz-tp7562101.html
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[Dominic Baines]

Matt, yes understood, transverter needed...but with KX3 not seen a circuit diagram yet, block diagram yes... wonder why that is still secret squirrel.... however I wonder if the offer from Wayne for the 160m IF went anywhere. I read that the KX3 is 'deaf' if you go through the normal RX chain at MF so wonder if anyone tried to break out yet.

I had hoped to use the KX3 for RX directly. I can see the SDR might be interesting as I use the Softrock at 500KHz on RX with a simple 4MHz crystal oscillator. http://m1kta-qrp.blogspot.co.uk/2008/10/500khz.html

I also have used the G3XBM 500KHz transverter with FT817 for 500KHz with 28MHz LO but my FT817 is dead now ;-)

BTW I have UK NoV for 500KHz.

72
Dom
M1KTA

[wayne burdick]

Matt Maguire wrote:

> Did you read in that article how a KXV3 module is used in the K3 to  
> bypass the high pass filtering used to protect the T/R PIN diodes?  
> The KX3 has the same filtering, but no possibility for a KXV3  
> module. Therefore, the KX3 is not really usable below around 1500kHz.

It is usable for receive, but not for transmit.

The high-pass filter starts rolling things off around 1.3 to 1.5 kHz.  
Sensitivity is certainly reduced at the low end of the band, but  
atmospheric noise is generally very high in this band anyway, and in  
practice the S/N ratio is adequate for casual AM broadcast listening  
over the entire band. If you're interested in weak-signal AM broadcast  
work, a transverter would be useful.


> If you want to get onto the 600m band with a KX3, you'll need to  
> look at building a transverter.

I did an experiment with 600-meter transceive on the KX3 (around 500  
kHz). With the ATU installed, which provides additional filtering for  
the broadcast band, the transmitter put out about 0.5 to 1.0 watts.  
But additional low-pass filtering would be required, and as noted  
above, receiver sensitivity is reduced in this band due to the high-
pass filtering.

73,
Wayne
N6KR


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[wayne burdick]

Matt Maguire wrote:

>> Therefore, the KX3 is not really usable below around 1500kHz.


I wrote:

> It is usable for receive, but not for transmit.
>
> The high-pass filter starts rolling things off around 1.3 to 1.5  
> kHz....

Er, that's "MHz".

Wayne

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[Dominic Baines]

Wayne,

Please can you make the KX3 RX front end circuit diagram available, possibly with the PCB mask, even if only personally? I am convinced it must be possible to bring the 472/500 signal in and bypass the filtering. I already have used with considerable success a 7 pole filtering on other SDR RX front ends to remove any interference from MW stations.

BTW whilst mentioning interference in 6W KX3 had broad interference from 15.3MHz station (Called RFI... a French language broad cast station) on top end of 20m. Did not matter how I tuned the station the other station could always be heard. There was deep qsb on the band at the time and it faded away and did not repeat but the whole front end (yes I had pre amp enabled) was over loaded. I have a recording of it.

72

Dom
M1KTA