[minima] Re: 25 mhz IF ahoy!
- From: allison <ajp166@xxxxxxxxxxx>
- To: minima@xxxxxxxxxxxxx
- Date: Tue, 02 Dec 2014 22:57:19 -0500
On 12/02/2014 10:36 PM, Ashhar Farhan wrote:
> gang,
>
> i recently found out a bag of 25 mhz crystals in my junk. i found that
> these are fundamental mode crystals! if this is a regular thing, then
> we can probably shift to 25 mhz IF instead of 20 mhz. here is why:
>
of the common ones I know of 22.118, 24, 25, 32 and 36 are available in
fundamental mode.
I've built filters at 36mhz for one receiver.
> 1. We get back 21 MHz band. with the IF and it's associated traps at
> 25 MHz, we will lose out 24 MHz band though. Some would (I would)
> consider this to be a fair bargain.
>
> 2. For those who are not too bothered with 10 meter coverage (I am,
> actually) a 0-21 MHz Minima would be very easily put together with a
> simple J-FET KISS V3 or V2 mixer.
>
The other direction is 11mz if for a 80 though 40 and 20 though 10M.
That would loose 30M.
There is also 9mhz (TENTEC still uses that IF in the Eagle and ArgonautVI).
I do know people that use Elecraft K1s and they only go to 15M. so they
would like that case too.
> 3. We could even place a 28 MHz band pass filter in parallel to the
> LPF to bypass the LPF (cut-off at 22 MHz) for 10 meter band alone.
>
For the 25mhz case using narrow band pass filter 28mhz is works and low
pas with sharp
cutoff for 80 through 15M
Allison/Kb1GMX
> - f
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