Bob's design of an LNA front end for Hydrogen LIne observations with 50 Ohm referencece switching

[Stephen Arbogast]

All,   

I just watched the  latest  RTOP  on  You Tube where  Bob  showed and discussed   his    design  for  a  two stage  LNA  with a  switch to a  50 ohm load.  He  mentioned  the  cost   is  about  $100. per  prototype board  with a minimum order of   5  boards.  Yes,  this  gets  expensive   but   here is  an idea...  What if we  join  together  to  order  the minimum  5  boards  each  paying  the  total cost  divided by 5?

It's  like Crowd  Supply...... and  by the  way   the  Discovery Dish Drive  funding  is up to  81%

One more  thing...  about software   for collecting   and post  processing  data  for   Hydrogen Line.  I  won't mention  names to protect the  innocent    but  two  members  have  sent  me  their   experimental  Python  code.  I am  having  a  lot  of fun going  through their  code  and learning  how   the  same  objective  is reached   by  different  coding approaches.  My  thoughts...  a  great deal  about   radio  astronomy can be learned by  software  not  just  hardware.

Stephen

Stephen

[Preston Ozmar]

Hi Stephen,

I am also interested in buying one of the boards from Bob, hopefully with the components installed. I have done a lot of soldering over the last 60 plus years, but not with those types of components. So, count me in.

Thank you,

Preston Ozmar

 

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[Stephen Arbogast]

If  enough people are interested some  one can  be   appointed  to  collect the  funds   and  order the boards. They will  be prototype  not   production.     

I have had  good  luck  with  JLCPCB    in  the  past.....  with  FR4  at low  frequencies.

But  then  the  volunteer  will have to mail  out  each  board which  will   cost  postage.  

JLCPCB   will pick  and place  the   components if they  have them.   

I have  hand  soldered   surface mount  components by hand   but  I   ain't getting   any  younger.

Stephen

[Stephen Arbogast]

I am not  sure  that  this is legal      might be fraud.....    I  am not a  lawyer.

[Richard Flagg]

All,

I also watched Bob's presentation and would be very interested in purchasing a populated board, preferably using the board material that optimizes low noise performance (if say it is a tenth dB or more better than FR4).

My use would be at S-band (2200-2300 Mhz) so I would  bypass the hydrogen line filter.

Bob's design looks great with the 50 ohm noise calibration source included.

I could do my own board performance testing - just have to hope that the fabrication is 100% correct as changing out any of the ICs would be beyond my shaky hands capabilities.               

Dick

AH6NM

[Stephen Arbogast]

I  think  this might   be  worth   considering ......     I am  up  for sharing costs......

Stephen

[Marcus D. Leech]

On 2026-04-21 01:50, Richard Flagg wrote:
>
> All,
>
> I also watched Bob's presentation and would be very interested in
> purchasing a populated board, preferably using the board material that
> optimizes low noise performance (if say it is a tenth dB or more
> better than FR4).
>
> My use would be at S-band (2200-2300 Mhz) so I would  bypass the
> hydrogen line filter.
>
> Bob's design looks great with the 50 ohm noise calibration source
> included.
>
> I could do my own board performance testing - just have to hope that
> the fabrication is 100% correct as changing out any of the ICs would
> be beyond my shaky hands capabilities.
>
> Dick
>
> AH6NM
>

I designed a very similar board perhaps 16 years ago, based on discrete
parts (some ATF-series FET).  The issue is that the gain derivative of
the two
  LNA "paths" will be slightly different, even if you take great pains
to match components and mount it on a big chunk of aluminum (so that the two
  active devices both see the same thermal "fate").

Will this approach "work"?  Sure.  Will it allow you to "reach down"
into the noise and pull up weak continuum sources that would otherwise have
  been ambiguous (due to thermal drift)?  Likely not.

However, the experimentation, if you stick with FR4 boards, (0.032"
boards will offer less dielectric loss than the standard 0.0625", but
you have to
  scale the micro-strip line widths appropriately).  Is relatively cheap.