2200 Meter SoftRock Lite II

Any good project starts with some scribbling on paper…

With the 630 meter SoftRock Lite II working well it was time to turn my attention to putting one on 2200 meters. There is no standard SoftRock which covers this range so I would have to make a few component substitutions. The changes are all very minor except for the crystal which cost more than the SoftRock kit! Something around 455 kHz is ideal. I ended up buying a 455 kHz carrier crystal from INRAD. Several capacitors in the oscillator would need to be changed to higher values, namely C10 3900 pF, C11 2700 pF, and C12 680 pF. I also changed R16 to 10k ohms because I find the oscillator never runs properly with the stock value.

The front end was also going to need some changes. C3 becomes .005 uF. C4 should be .16 uF but I used a .15 and it worked well enough. L1 is 267 uH. I used 25 turns on a FT-37-43 core. T1 primary should be 8.23 uH. I used 12 turns on a FT-37-61 core. The secondary is 6 bifilar turns. This input circuit has a bit of loss (about 2 dB) but I considered that acceptable since I was unable to come up with a better design that was also practical. As with the 630 meter unit, additional front end selectivity would be needed. I duplicated the C3, L1, C4, T1 primary once more and placed the circuit on a small prototype board.

Internal view of completed receiver

The finished receiver works well. I have been hearing WH2XND very well every night. I have heard Europe on WSPR-2 mode four consecutive nights, three of those nights DC0DX and the one night G8HUH. There were no problems with out of band signals until I added a preamp, at which time I had to put an outboard bandpass filter in line to keep things clean. LO frequency stability is on par with the 630 meter unit. See my earlier performance evaluation on that for details. I am happy with the performance and this is now my primary 2200 meter receiver.

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  1. Pingback: 2200m Reboot: The Receiver | N1BUG Adventures in Radio

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