[Elecraft] To: Elecraft- Suggestions

[wayne burdick]

On Mar 2, 2009, at 6:57 AM, -.-. --.-N3TU -.-. --.- wrote:

>
> Is it possible to have the radio go down to .100 khz instead of where 
> it is
> now which is 500 khz?

Hi Greg,

The synth was designed to go down to only about 9 MHz, which means that 
in theory the typical K3 could tune as low as about 300 kHz (9.0 - 8.7 
= 0.3). Some might even go a bit lower. But since they can't all go 
down this far, we put the cutoff at 500 kHz (below the AM radio band).

There's another factor involved: the PIN diodes in the TR switch. In 
order to ensure low IMD, we built a high-pass filter into the TR switch 
that starts rolling off below 1 MHz. It's down about 20 dB by the time 
you get to 500 kHz, and it would be more like 30 dB at 100 kHz. The rig 
just wasn't designed to cover this range.

That said, I've added an "experimenter's VLF mode" to my firmware list, 
just in case you want to try it.

>
> Is it also possible to have receive coverage from 30mhz-99mhz? If you 
> take
> it out of transmit with a flashing "tx" and press the XMIT and spin 
> the dial
> for a while, the frequency readout will go all way up to 99.99 mhz? 
> When you
> try to transmit on those frequencies with a dummy load , the radio will
> default back to 30 mhz. It would be nice if we could receive on those 
> since
> the radio says it's there. Can you change the software to open up this 
> "back
> door?"

The reason we don't do this is that the band-pass filters, low-pass 
filters, and 32-46 MHz band-stop filter all greatly attenuate signals 
outside the specified range (0.5-30 and 48-54 MHz).

The way around this would be to build a wide-range, band-switched 
transverter. This is left as an exercise for the reader :)

73,
Wayne
N6KR