EMRFD Message Archive 14252

Message Date From Subject
14252 2017-09-03 13:21:34 jwolczanski Binaural Receiver

Finished up the final circuit board this morning and, after one hiccup (reversed wires on home-brew mixer), got it playing on the bench.  Can't wipe the grin off my face. 

Got nine circuit boards all lashed together with clip leads and fixed wires.  Picking up some hum, but that's not detracting from the listening experience.

Now I gotta think about packaging.

What an intriguing design - thanks Rick!



14253 2017-09-03 14:28:47 Bill Carver Re: Binaural Receiver
Your grin is OUR grin, Jerry!
Ain't homebrewing wunnerful?

14283 2017-09-08 16:33:30 jgaffke Re: Binaural Receiver
I've got the $21 Softrock LIte II for 40m.  
Correct me if I'm wrong, but I think I should be able to remove the crystal and drive that node from an Si5351 breakout board at 4*7=28mhz, listen to 40m binaural signals directly from the Softrock's stereo line out.

Could just use the Softrock's 4*7.056mhz crystal, but you would be stuck listening only to signals at 7.056.  Audio out of the Softrock extends well beyond 20khz, I assume my headphone amp and headphones will be able to deal with that.

Yet Another Jerry, KE7ER    Flora OR, USA

---In emrfd@yahoogroups.com, wrote :

Your grin is OUR grin, Jerry!
Ain't homebrewing wunnerful?

14285 2017-09-08 21:55:13 Ashhar Farhan Re: Binaural Receiver
Very good recording. what was the burst of noise at the end ?

- f

14287 2017-09-09 05:30:12 jwolczanski Re: Binaural Receiver
Good morning Ashhar.

I didn't hear a noise burst but there was an odd carrier at the end with a rough sounding signal.  I was turning the dial on the tuning capacitor and reaching for the recorder controls (a Sony PCM-D50).  I've included a photo of the receiver entitled "Binaural Receiver lash-up.jpg" in my files section.

top left, the RF splitter
Little board above the yellow handle is the LO splitter
two mixers
Two preamplifiers that use a diplexer from "Solid State Design for the Radio Amateur".  All the selectivity this radio has is from these venerable 88mH toroids in that preamplifier.
Two audio boards

I added an LM380 amplifier at the end of the published design with a ganged pot.  Not shown in the photo:  I snipped into the hot end of the pot to obtain headphone audio. The recording was made from audio derived at this point.  The LM380 easily drives a 3 - 4" speaker.

Also not shown, I added a 1K pot on the antenna input to use as a gain control.

I made a LO that runs at 3.5MHz and used a doubler.  The output was 20dbm - on the advice of Chris Trask, I used series diodes in my home-made mixers.

The radio is just plain FUN to listen to!

I'm gonna leave it on the bench for a bit longer before I think about how to enclose it.

Warrenton, VA