[Elecraft] K2 FM BCI - one step closer (and one step back)

[Larry East]

At 08:26 PM 6/9/02 +0200, Sverre Holm - LA3ZA wrote:
>One can easily simulate the FM broadcast interference by using a
>grid-dip meter as a transmitter at around 100 MHz. It leaks right into
>the K2 in the 20 m band just as has been reported for FM stations. No
>wires attached except for power, no covers opened. Ferrites on the power
>supply connection has no effect. Turning on the preamp makes it a little
>stronger, but not the 12 dB or 2 S-points or so that it is does at HF.

I wonder if the FM interference is present only when using the "RX Ant." 
input, or with the normal antenna input as well. When using the normal 
antenna input, the signal passes through the low pass filter as well as the 
band pass filter. When using the "RX Ant.", it appears to me that the LPF 
filter is bypassed. Although there could be some significance leakage at 
~90-100 MHz through the 20M BPF, I would think that the attenuation of the 
20M LPF at these frequencies would be in excess of 50 dB.

>   .... and the lights went
>out. I had connected it to 12 Volts instead - no more mixer - input
>transfomer burned off!!!!! - end of experiments!

Bummer!!


73,
Larry W1HUE/7