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@Robb Greetings, The filter takes virtually no test equipment. Really it either works or it doesn't. For the diode detector a simple pc sound card o'scope can be used which are free on the internet and a if you have a soldiering iron already - you can make a probe with parts on your bench...

@711: I think my explanation was flawed. The crystal IF filter is inserted at c47( as stated above) and the precision diode detector replaces the AM rectifier diodes in the 455khz area. Please have a look at the pictures I uploaded in the first post of this thread. You can see the IF filter...

@Flatlander: You can use any small signal diodes you have. I've used 1n4148, 1n60p, it doesn't really matter. The secret to the diodes is use ones that have the closest voltage drop. Use your dvm in the "diode" mode and find three that are closest. I found when purchasing diodes it's best...

Greetings, I've included the schematic for the crystal IF filter as an attachment. The PITA for this project is finding the crystals. I've harvested mine from a defunct 148's 7.8 mhz ssb filter. After installing the unit I simply adjusted the bandpass filter (gave it the golden screwdriver...

I agree. Really the point of the post is to show an alternative to the shottky diode setup. One that might cost a few cents more (maybe not if the parts are bought in china) but commands a respectable increase in performance. The precision diode is not the end all of mods but it's job is a...

Thanks for your reply. Many CB radios aren't superb, whatsoever. You talk about Uniden or Cobra as the designers of diode detectors but they aren't. Diode detection is a method of demodulation, a really cheap way of AM demodualtion at that. Lame diode detection has many drawbacks technically...

If you scrap it, I would be willing to buy it off you for a decent price and pay shipping

Is the PLL in lock? Does TR37 operate correctly? Does TR35 switch properly? Pin 5 on the Voltage Regulator is the control pin - when pin 5 is high pin 6 supplies rx only voltage and when low pin 8 supplies the TX only voltage. #248 - If this goes low there will be no TX source voltage. Also...

His work is silly and useless at best.

When it comes to Cobra 148/2000GTL receive mods there seems to be only a few. The most notable able is the (1) 1st rf amp and (2)dioide swap and finally the (3)"Goldfinger" cap mod. I purchased all the parts to do the 3 mods. As I stared at the parts I thought, "Wow, lots of parts...I hope I...