Listen to Latest SolderSmoke Podcast

Monday, February 10, 2014

BITX 2040 Build Update #9: On-the-air Observations


The BITX 2040 has moved from the bench to the operating position and is producing a steady stream of contacts on 20 and 40 meters.  In the picture above it is the rig with the copper-clad front panel (the BITX 17 is below it).  It has already crossed the pond on both bands.

Some observations:

I get significantly more power out on 40 than on 20:  about 7.2 watts PEP on 40 and about 4.4 watts PEP on 20.  I saw a QST article that showed similar frequency/power out variations from IRF510 amps.   But I notice I get more power out from my 17 meter rig.  On that rig I am using trifilar (9:1 Z) transformer instead of the standard BITX bifilars. 

My 40 meter receiver is LOUD.   Too much AF out.  I am not used to having this problem!  On this rig I am using the same discrete component 2n3904 2n3906 transformer-less circuit that I used in the BITX 17.  But AF out on 40 was so loud that I had to go back and add 20 k ohms to the top of the volume control pot.   I didn't have this problem with the 17 meter rig, and I didn't have it on 20 with this rig.  Any ideas why this rig would be so loud on 40?

I still want to go in and fine tune the crystal filters in both rigs.  I am studying the various software packages out there (especially Wes's LADPAC).  I hope to get rid of the ripple.   

In most of my contacts with these rigs, I end up describing the circuit and its Indian origins.  Most people are really fascinated.  Yesterday W1IDL in Michigan suggested that I contact my Indian friends and get some assistance in making some Hindi or Urdu labels for the rig and the controls.   I think that is a very cool idea. 

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

1 comment:

  1. Do the fully-enclosed rigs make you an 'appliance operator' now?

    All kidding aside... nice work.
    Some of my stuff never makes it to an enclosure.

    Bill N5AB

    ReplyDelete

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column