Wanting to build a small portable transceiver but tired of the bureaucracy of component searching, I decided to build Dave Benson's, NN1G, GM-20 from a kit. The feeling of accomplishment is not as great as making one from scratch but if you hate the hassle of hunting for all of the components yourself, it's a good option.
The 'Green Mountain' series of transceiver kits were offered for each of the HF bands between 80 and 10 Metres, including the WARC bands. I chose the 20 Metre version. As it's a board only kit you need to add the controls and enclosure. The GM-20 is the 20 Metre successor of Dave's SW-40 rig.
1. Narrow crystal filtering
2. Full QSK operation
3. Low noise receiver
4. Good frequency stability
5. Nice audio using an LM-380 audio final amp
6. Output power about 2.5 Watts
7. On board RIT
8. Approximately 80 KHz frequency coverage
9. Superhet design
10. With minor changes can be placed on any band.
It's manual has a description of circuit action, a step by step building procedure and a troubleshooting section. Construction is straightforward, although care must be taken in winding the toroid coils - the winding instructions must be followed to the letter!
Lacking controls and an enclosure can be an advantage. As well as lowering the cost, you then have the option of adding a case and controls of your choice. I opted for this 'emergency orange' style case, sub-miniture toggle switches and a multi-turn potentiometer with vernier-dial knob for smooth tunning. The other extra I incorporated was a small built in iambic keyer.
Performance is excellent considering the receiver's simplicity and couple of watts output - I regularly work DX from hotel rooms using a simple random wire antenna. I see from Dave's site that the GM-20 is no longer advertised but he has other kits available including a promising PSK31 transceiver. Check out the Small Wonder Labs site.
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