Submited By Nadisha 4S7NR
Looks very simple. But need bit experiance to build this receiver. It can be tuned from 140 to 150 Mhz covering the whole 2m band. This has a Super Regenerative detector. When properly tuned and aligned the receiver is very sensitive. The original author R.H.Longden writing in a Practical Wireless artical says that he could hear transmissions of 10 miles with a 6 inch wire antenna.
Receiver must be enclosed in an metel box and Tuning spindle should be fixed with a plastic knob. One should never try to construct this on IC boards or Vero boards.
L1 and L2 Coils should be wound using 18 SWG wire and L1 is only one turn where L2 has 4 turns (7/8 inch long). They are air wound on 1/2 inch diameter form. L2 should be next in-line to L1. Changing the turn spacing of L2 change the frequency. So you will have to experiment and find where it tunes. If you have an signal genarator - with in no time you will be in the business. L3 is not very critical, it has 30 turns of 26 SWG wire on a 1/4 inch diameter air core.
Once evry thing is okay, connect an audio amplifier, similer to LM386 and a sutable antenna to the receiver. Turn the 25k pot (Regen Control) where a strong hiss begins. This is roughly the correct posision. This hiss should cease when any signal of sufficiant strength is tuned in. Tune the 10pf tuning cap to search any stations or tune your signal genarator to see where the receiver is tuned. Once you know the place, adjust the coil. To increase the frequency, you will have to stretch the turns of L2.
I tried building this receiver on a breadboard,ugly construction on a piece of pcb,and created a pc board,no matter how much I fudged with the components the radio didn't work!!
ReplyDelete