[hpsdr] [Hpsdr] Call for Comments - ALEX

[Graham Haddock]

Shel:
Comments below.
--- Graham / KE9H

CT1IZU wrote:
> In front of the 6Mtr LNA though as a BPF the MC120  may still
> be appropriate. I use them in two hombrew tranceivers for 6 and 4 meters
> with 4 pole bottom inductor coupling and 17dBm mixers, so far without
> issues.
>   
I still need a design for a 6 meter LNA.  Do you something that might be 
appropriate to use here?
Anyone?  If not, I am going to use a 50 Ohm gain block with noise figure 
below 2.5 dB. I found one
with a noise figure below 1 dB that might work.
> Air coils sound appealing but I wonder how easy it will be get tight control
> of the inductances on the 33 or 55Mhz filters? Would it be better to use  a
> filter where the meshes are tuned by a small trimmer cap?
>   
Well, if the person building the ALEX already has a MERCURY and a 
PENELOPE that is working,
then they should be able to be used as a spectrum analyzer and tracking 
generator signal source
to very exactly align an air core coil, or check for the filter shapes 
on all of the filters.  On the
Cauer/elliptical filters, you would set the inductances by setting the 
frequency of the notches.
That should work real well, if we get the spectrum analyzer software in 
time.

--- Graham / KE9H

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