[Elecraft] Broadcast Break though on 160m

[Brendan EI6IZ]

On Sat, 2004-10-09 at 13:09 -0700, Kurt Cramer wrote:
> This sounds like an image. The IF is 4.915 MHz and I think the VCO will
> be 1.9 above the IF, or 6.815 MHz to receive 1.9. The image would be
> 11.73 MHz. Am I right? If I am then, I don't know why the bandpass
> filters are not putting them way down. But if the signal injection is
> not coming from the antenna.....? 


Yes the image reception is of the 11.7 Mhz broadcast band (25m band) and
it's only those 'monster' signals that manage to get in. In the Early
evening I see signals as big as -10dBm here on the 25 M band so it
probably takes the combined efforts of the bandpass filters and the TX
low pass filters to tame signals that large.. 

if it was just getting in via the RX antenna socket I would put a Low
pass filter in line with my RX antenna but merely activating the RX
antenna seems to allow the ingress to occur even when no rx antenna is
connected. The RX antenna circuit bypasses the output low pass filters
when activated so I guess that's the route in.

Modding the K2 to connect the RX antenna after the LP filters looks like
it isn't a practical option but I wonder if a trap for the 25mb
broadcast band can be engineered (hacked!) into the K2 before the band
pass filters to give some more rejection?

73
Brendan EI6IZ 


-- 
Brendan EI6IZ <ei6iz at oceanfree.net>