20-Meter High Performance Direct Conversion Receiver (2)

Partially checked out the RX ckt on the bench today. I powered the board off a 12V supply.   No external components were attached, including the VFO tuning cap and the peaking  cap.  The antenna coil is still missing. 

The voltage at  oscillator transistor Q4 drain is 8.9 volts, so voltage regulation of the oscillator power seems to be working. 

The oscillator, without the front panel tuning cap, operates at 14.365 MHz.    Amplitude is 638 mV pp, so 0.23 V rms.  

Next step will be to install a new antenna coil and repair the peaking variable capacitor.  I went to Four States QRP to order the toroids, but weren't in stock.  I ordered some T30-6 rather than T37-6, so I'll try to use those. 

20-Meter High Performance Direct Conversion Receiver (1)

Figure 1.  Photo 20m RX PCB

Today I'm starting work on the 20 Meter receiver that Mike bought back in 2018.  The receiver is based on a April 1978 QST article. (Page 11). 

• The circuit is fairly simple and shouldn't be too hard to fix.
• I found a 12 volt 2 amp "wall-wart" power supply to power it with.  I don't have a jack to go with it.  I'll have to kludge something.
• The toroid that comprises L1/L2/L3 is missing.  I may have to order a T37-6 core to replace it.   

 

Layout of the reciever board taken from the magazine article. 

The view is from the copper side.  The component side is a mirror image.