As you can see (above) I've made lots of progress on the BITX-17. Going counter-clockwise from the lower right, you can see the mic amp, the BFO/carrier oscillator, the first mixer, the first and second bi-directional amplifiers, the diode ring VXO mixer and the VXO.
I plan on building the whole rig (including the power amplifier stages) on this wonderful piece of PC board (thanks to Jim, W8NSA).
I had what I thought was the brilliant idea of using LEDs for all the T/R switching diodes. I thought I'd use red for receive and blue for transmit. I consulted with the BITX yahoo group and cooler heads prevailed.
The design has an LM-386 as the speaker amp. I'm kind of bothered by this -- I'd prefer an all-discrete component rig, so I am thinking of building an AF amp with discrete transistors instead, perhaps the circuit from Roger Hayward's RX for the Ugly Weekender. What do you all think about this?
I'm having a lot of fun building this rig. If anyone out there is looking for a fall/winter project, build one of these.
I have to order some 5 MHz crystals for the filter and oscillator. Mouser has them at about 70 cents each.
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A few years ago, Jim Kortge K8IQY built an entire Tx/Rx using just 2N2222's. http://www.k8iqy.com/qrprigs/2n240/2n240page.html
ReplyDeleteMaybe you could use some of this Bill?
K4ICY describes a simple three-transistor audio amp here:
ReplyDeletehttp://www.k4icy.com/weekend_radio_3tr-audio-amp.html
I built it using two 2N3904s and one 2N3906. Works fine, with plenty of audio.
Jerry AA6KI
Tucson