Re: Bitx 20 3b "ugly" build

Laurence Oberman
 

Would love to see a picture of your Rig  MadRadioModder
Sound like a really good project you built.
Your forum name is definitely is earned for that work :)
Regards
Laurence

On Thu, Apr 25, 2019 at 1:44 PM MadRadioModder <madradiomodder@...> wrote:

I did this last year… constructed an entire uBITx v4 from scratch but built it in modules for each stage so that I could replace stages with newer experimental designs to try them out.  Two or three others did the same thing.  I designed a backplane with power, agc, control signals that the modules could plug into.  In the end I replaced the front end with a PGA103+ mmic and two PE4306 attenuators, other stages with dual gate ultra-low noise FETs (for AGC control).  Also used a modified version of the K2 crystal filter scheme for variable pass-band.  Then built a second receiver and modified the CEC code fit into a Teensy 3.6 to control both receivers at once (split).  The teensy also does DSP filtering (passband, notch, etc. for both receivers).

 

A couple things to glean from this experience (and to conform to good RF design in general) were:  1) bypass the rails and control lines well… everywhere. Then do it again.  2) enclose each stage in a shield (simple made from circuit boards works perfectly)… this keeps cross talk and spikes from adjacent stages to a minimum

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of n7ql.us@...
Sent: Thursday, April 25, 2019 6:59 AM
To: BITX20@groups.io
Subject: [BITX20] Bitx 20 3b "ugly" build

 

I am getting ready to attempt a Bitx 20 3b build but instead of PCBs I am going to go the "ugly" route. I have many of the parts already and the few I don't I'll buy but it will be cheaper than buying the whole kit. I am wondering if anyone here has gone this route and how well it turned out. Thank you.


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