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Dear forum, I have a DDS ( PA2OHH's ) and want to try this as an LO of my BITX. for reason I don't need to add a frequency counter, and he PA2OHH is succeed used DDS as 5 to 5.5 MHz VFO (for an old

Hi Due to similar observations with my original BITX20, I used 1/4 inch wide slices of 1/2 inch ID PVC pipe as the formers for my BITX40. The results caused me to recently replace black plastic

It would seem not all faucet washers are created equal. After completing my bitx20 main board I was disappointed with the rec gain. I upped the audio gain by increasing the feedback cap on the lm386

I used a dip meter to roughly adjust the individual LC's to the correct frequency. Then I connected them together and peaked them. May be adding the capacitor on one coil, did change also the

I am adjusting the receive BPF using a sine wave generator and oscilloscope. The first of the three sections peaks at about 14.2 Mhz, but the second peaks at 16 Mhz. I tried to add 12 pF additional

Dear Arv and friends, Hi! Here in keeping with common availablity I went ahead with BITX20 version using off shelf components. I used BC547s available, probably Chinese varients. The performance

See also in the Files directory 'modifications', 'clear LF' to improve the loop gain of the LM386. The capacitor should be made 10uF. My BITX17 is not generating a loud noise but when a station is

Paul On my BITX20, and the BITX40, I used an AF design that is different from the LM386 that Farhan specified. There are some schematics of this in the BITX20 Group files section under K7HKL. My AF

Ron I'm referring to the current consumption of the crystal oscillator timebase, not the VFO. With a 4.096MHz crystal it was about 3mA, with the 32kHz it is about 30uA. I don't remember what the

Dear Paolo and Hans, Sure Paolo, in general a mixer circuit (whether passive or active) generates both sum and diff. frequencies. Proper filtering after mixer selects your required (set of)

Ron wrote: Don't forget: 2*8.1 - 10 = 6.2 MHz 3*8.1 - 10 = 14.3 MHz (that would make it a dualband BITX changing output filter... should check the diagram, I am fantasizing) The mixer returns both

Hi Ron I think it should be fine. If you look at the waveform at the mixer port of the original BITX it isn't very sinusoidal anyway. When I get a chance, I will put my homebrew spectrum analyser on

Thanks for your research and the good www. information dr Paolo, Harmonic response for my BITX17 would be as follows: LO: 8.1 MHz 1 : 18.1 MHz 2 : 2x8.1 + 10 = 26.2 MHz 3 : 3x8.1 + 10 = 34.3

Ron wrote: Hi I have located an interesting whitepaper on Waveform Conversion (sine to square and square to sine) at: http://www.wenzel.com/documents/waveform.html This document is linked from

Thanks for the advice Hans and of course good day to all the other bitx-ers, If used for the BITX design, do you think the squarewave output signal can remain unchanged and directly be fed into Q7

Hi Ron Thanks! Filtering on the VFO output: yes it's a squarewave, which is rich in odd harmonics - but whether you filter or not depends on what you need the output for. For some types of mixers I

Hello Hans and bitx-builders, I had a look at your minimalist 2 chip VFO&HUFF+PUFF circuit. Splendid design. Chapeau! I assume filtering at the VFO output is required since the squarewave contains

there is little to be gained doing that. but it can be done. you should decrease the feedback resistors from 2.2K to 1K. This is because the RF path sees both the 2.2K paralleled together. that

Hi all, Does it make any difference if the receiver only portion of Bitx is assembled for learning and demo? I think some gains may be affected. Has anyone tried it? 73 SP Bhatnagar

For those on the BITX20 who aren't in the HuffPuffVFO forum - I have added a new minimalist Huff Puff design to my page, this one uses the so-called "fast" Huff Puff architecture developed by Peter