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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

Fernando LW5DNC I have built a BITX20, a BITX40, and am slowly working on a BITX-LF for the US LF band (160 to 190 KHz). Farhan VU3ICQ's original design seems easy to modify for other bands (there

HELLOW FOLKS : ANYBODY IS EXPERIMENTING WITH BITX IN 80 MTS ? BEST REGARDS FERNANDO CASARI LW5DNC ARGENTINA

Hi BITX-ers, Just when I thougth the job was done I discovered problems in the PA stage: output when there was no modulation. First I read all the messages of this subject posted in the past in

Ron If it is really AM, then check the diodes to make sure both are still good, and that one is not in backwards. If it is DSB, then verify that your carrier oscillator is about 400 Hz down the

Dear BITX'ers, Just did some trials with the BITX17 transmit section (no PA installed yet). I am a bit puzzled now. When I switch on the TX (no modulation yet) I can hear 2 sidebands on my Philips

Counterfeit electronics. < http://sound.westhost.com/counterfeit.htm > Jim N6OTQ

Hi Julius, if you build only the receiving part, you do not need to make the bi- amps. You can do with single amps. However, then a value of the resistor needs to be changed. You can find that out