Wednesday, February 20, 2013

Speaky panadapter

 I wanted to have an unfiltered IF output on the "Speaky" so that a panoramic adapter could be connected or even a second receiver for AM and FM reception, case needed.

 So here's the story of a simple amplifier circuit from the original article here.

The schematic:

 The original author used it for an Kenwood TS-120 and 130. In my case I had to find a convenient place for insertion and decided to connect E(in) to DR11 just at the input of the post mixer amplifier, just before the crystal filter.

E(out) connected to a BNC plug on the back of the transceiver.

Power is from pin 19 (10V on reception that switches the mixer output signal to the post mixer buffer, T12 and T13). The circuit gives a little more output with 13.8V but it's working fine with just 10, and I had no problem copying all the signals using an FT-817 as the 8Mhz IF.

Bill of Materials

C1, C5: 0.01mF/±20%/50V/X7R/Ceramic
C2: 56pF/±5%/50V/NPO/Ceramic
C3: 1000pF/±5%/50V/NPO/Ceramic
C4: 0.1mF/±20%/50V/X7R/Ceramic
C6: 4700pF/±5%/50V/X7R/Ceramic

For caps I used normal ceramic.

L1: 3mH toroidal inductor: (I used unknown toroid from a switch mode psu with some 8 turns that has enough inductance at 8Mhz)
7T #24 on m=125, AL=55 ferrite core (Amidon FT-37-61) or
6T #24 on m=125, AL=75 ferrite core (Amidon FT-50A-61)
Q1: NPN transistor: 2N3904, 2N2222, etc. (used 2n3904)
R1: 2K10W/±1%/¼W Metal Film (or 2K2W/±5%) (used 2k)
R2: 4K75W/±1%/¼W Metal Film (or 4K7W/±5%)
R3: 10K0W/±1%/¼W Metal Film (or 10KW/±5%)
R4: 274W/±1%/¼W Metal Film (or 270W/±5%)

All resistors I used were carbon 10% and not metal film 1%.

Circuit was build in a small piece of PCB with ground place on one side and components on the other, then wrapped in heath shrink tape:
Here's the outcome in place:

..I still need to tighten those cables...

have a nice day!

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