HFI 2014 – BITX40 Design – Everything you want to know!

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BITX40_built_HFI14At the HamFest India 2014 conducted on 7th and 8th November 2014 at Hyderbad, a PCB of BITX40 Transceiver was distributed free as a part of the welcome kit.  The BITX40 is a variant of Ashar Farhan’s (VU2ESE) original BITX20 design.  Being the Convener of HFI 2014, Ashar Farhan created this BITX40 specifically for the HFI 2014 delegates and a PCB was made part of the welcome kit.  More than a thousand PCBs were distributed, in the view of improving Hombrewing activities in India.  Also a 40 Meter design was chosen as there is a lot of activity on the 40 meter band from South Indian HAMs including some everyday Nets.  It also becomes easier for the home brewer for testing.

Please note the BITX40 design in the below write up, diagrams and PCB has some errors. Please see the video below, along with the correction notes before starting your build.

Here is the scanned write up from the HFI 2014 Souvenir:

(Click on the image to make it bigger. Images are high resolution,  may take some time to load on slow connection)

Hamfest India 2014 Souvenir - BITX40 - Page 1
Hamfest India 2014 Souvenir – BITX40 – Page 1
Hamfest India 2014 Souvenir - BITX40 - Page 2
Hamfest India 2014 Souvenir – BITX40 – Page 2
Hamfest India 2014 Souvenir - BITX40 - Page 3
Hamfest India 2014 Souvenir – BITX40 – Page 3
Hamfest India 2014 Souvenir - BITX40 - Page 4
Hamfest India 2014 Souvenir – BITX40 – Page 4
Hamfest India 2014 Souvenir - BITX40 - Page 5
Hamfest India 2014 Souvenir – BITX40 – Page 5

Picture of PCB distributed with the HFI Welcome Kit:

BITX40 PCB - HFI2014 Version
BITX40 PCB – HFI2014 Version

Here’s a video taken by my good friend Gurudatta Panda, where Ashar Farhan talks about the BITX40 Design:

BITX40 KIT

A vendor named Modern Electronics was also selling all the components (including crystals, toroids, etc.) required for this build.  Their contact details are here:

Modern Electronics
Bank Street,
Hyderabad – 500 095
Phone:  Nandlal Hemdev  – +91 40 66781264,  Neeraj Hemdev – +91 40 42215076
Email: modern_electronics4u@yahoo.com

Picture of the Kit is here:

BITX40 Kit by Modern Electronics, Hyderabad @ Rs.500/-

BITX40 Kit by Modern Electronics, Hyderabad @ Rs.500/-

Modern Electronics taking mail order for the kit @  Price Rs. 500 + shipping

As per comments below, Modern Electronics has updated their price to Rs. 1200/- 

 

Errors/Corrections

Ashar Farhan, VU2ESE also took a session showing some corrections to the errors that were made in the PCB/Design or while printing them in the HFI 2014 Souvenir.  I made a video of this session:

 

Correction Notes compiled with inputs from home brewers who have built it:

  • Ashok Joshi VU2ASH: Omit R69 50 Ohms and C32 0.1 uF
R69_C32
Omit R69 and C32
  •  Ashok Joshi VU2ASH: Audio of the receiver is very low, to correct this Change  R29 to 10 Ohms ; C73 to 0.001 uF and R64 to 10 Ohms.
R29_C73_R64
Change R29 to 10 Ohms, C73 to 0.001 uF and R64 to 10 Ohms
  • Ashar Farhan (email on bitx20 group): The bitx40 pcb has one error. the first mixer’s transformer T1A (the one that is connected to the RF amplifier) has a missing ground connection.  T1A’s primary and the center tap (formed by connecting opposing ends of the two other winding) should have been connected to the ground. instead, they are only connected to each other and the ground connection is missing. a jumper needs to be soldered on the PCB side.
Ground the 3 coil Junction of T1A
Ground the 3 coil Junction of T1A
  • Le Bleu Enchanteur VU2SWX:  The 12v line must be connected to bfo via jumper. It is printed on the component layout in the souvenir as j3 but not on the board. I just wired it and powered up. I can listen to the bfo at 8 MHz on my BC radio ( twice my current if). So the stage works.
  • Ashok Joshi VU2ASH: if you match the diodes for equal forward voltage drop, you don’t require the preset, 10 pf and 22pf trimmer in modulator section at all. Just short the preset three pins together.  Out of 25 or so diodes provided in the kit you can easily get two matched to milivolt range for the Balanced Modulator, Still I used the preset in my assembly, but had to keep it in exact centre !!

That is all for now, I will keep this post updating as and when I get more info.  Also Farhan and HFI 2014 Team has promised to come out with a video + Errata to the BITX40 Diagrams in the HFI Souvenir and errors in the PCB, with all the corrections.

If you have any suggestions or information to add to this post, please feel free to leave your comments below!

Amogh Desai

Amogh Desai

A System Admin by profession, is a tech buff and a licensed Amateur Radio operator with callsign VU3DES. He is interested in Technology, Amateur radio, Electronics home-brewing, FOSS, Photography and everything tech. He uses this blog to share his views and ideas with people sharing similar interests.
Amogh Desai
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27 Comments


  1. Very helpful.. And nice decision to record the video.

    Reply

  2. Well done Amogh. Please keep updating for the benefit of Builders

    Reply

    1. Thank you so much OM ASH, Included all your Corrections in my post. With this all the required corrections for a working and stable BITX are complete.

      Reply

  3. Hi, its nice that you have collated all the information related to bitx40. Really appreciate the effort. I am also making the bitx modules step by step. During this process understanding, epxlaining, asking and musing on the tech to make it understandable, usable to non-tech guy with soldering iron and faith on the original builder. have a look also at my blog. vu3inj[dot]blogspot[dot]in
    thanks
    73
    vu3inj

    Reply

  4. It is rally great really information to active builders. I would say amogh from Amogh Desai to co-relate and publish

    Ashok jee did a great job. Hats off t the entire spirited team.

    DDS addition makes life easier. it could also incorporate band switching that could later be used when members expecnd to multi band.
    VK5TM had published some such using e-bay module (AD9850) the data is there on yahoo group of bitx20 and also on DDS group .

    all the best and regards

    sarma (SWL) from Hyd

    Reply

  5. “Please note the BITX40 design in the below write up, diagrams and PCB has some errors. Please see the video below, along with the correction notes before starting your build”. 100% Good guidance AmoghDesai good job keep it up Best Regards 73

    Reply

  6. the price of pcb with components is not rs 500.
    The modern electronics asked me send rs 1200.

    Reply

    1. Thanks for informing..Updated the post.. Please get your own part.. it should be around Rs. 500

      Reply

  7. Please send me L1 L2 L3 L4 L 5 coils making how many turns and wire gage thinking you

    Reply

    1. Please send my mail Bitex transrecever (ham fest india2014)all inductors details like gauge turns my mail id (nus1959@gmail.com) thnkyou

      Reply

  8. At least I’ve bought the kit at ₹600. The price may vary according to shipping and demands I understand..

    Reply

  9. How can I get the kit or at least the PCB for the Bitx40 from HFI 2014 in Albania? I sent an e-mail message to Modern Electronics on the e-mail address mentioned above, but still don’t have an answer.
    Does anybody from India has a free PCB or the file for the PCB making through Toner Transfer method? I want to build the Bitx40, so even If I can get a PCB or the file to make it by myself is OK.
    Thank you and 73!
    Roumen, LZ4IR and ZA1IR

    Reply

  10. Dear Amogh,
    Please send me L4 L 5 & transformer T3 coils making how many turns and wire gage thinking you.

    Reply

  11. Thank You Amogh Desai ji, this blogg is very nice, I am following your blogg. can I find, still basics, can you please suggest me? 73. This is VU2VIZ

    Reply

  12. Dear sir tel me the value of C1,C2,C3 and describe VR1, L4, L5,

    Reply

  13. Hi amoghdesai I need 40m transceiver kit at low cost, btix 40m is still available? How to buy?

    Reply

  14. I heard that vu2ash has modified the latest smd bitx for multiband.Kindly post the details in the website.vu2rvk

    Reply

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