KØAWU's 10m SoftRock Ver6.2RxTx SDR , 144Mhz IF Application & More

Feb 2008 - Softrock Software defined 10m Transceiver

Jan 30, 2008 --- The transceiver is built and I am waiting on the crystal to start testing and packaging. The unit is shown with the oscillator board and a "dummy crystal". I am very excited about the Si570 programmable oscillator that should soon be available for all SoftRocks. Frequency agility for the SoftRock ... GREAT!!







Feb 5, 2008 --- The transceiver is built and packaged. I am crystal controlled for a frequency of 28.089+/- 48kc with the Delta 44 sound card. With this crystal, the frequency range is fine for 902, 1296 and 10Ghz here using the DEM 144-28 transverter (144.041-144.137). My use of the 10mRxTx is only for 144mhz IF use for VHF/UHF/Microwave.



















The recommended SM capacitor changes were made to the 10mRxTx. I first verified that the receive side was working normally. The Rx output from the DEM transverter is adequate to provide a "S4" no signal noise level. I then built the serial keying interface up. Everything was then mounted and TX tests were made. All looks as expected. On the transmit side, PA bias was nicely balanced, I/Q balance with Rocky was very good and 1 watt output was easy to obtain. I use a 6db pad in Tx between the Softrock and the 2m transverter. PTT is accomplished by using the switched 12v in the Softrock isolated by a 10k resistor and a transistor "switch".

.01mfd locations on Ver6.2 10m Softrock Updated 3/10/2008















The 2m DEM transverter I use is a 25watt unit. I have the SDR software set for reduced power output by about 20db. That plus the 6db pad in the Tx line and the Tx drive control in the DEM transverter allows a great range of output... near 0 to over 10watts output. For the transverters with a 144mhz IF I run about 1.5watts output. This level is compatible with the Yaesu 290RII I used before as the IF rig. That power range will be very satisfactory for xverter use, as well as driving the pair of 8560AS amplifier to 400watts for 2m use.













This screen shot was made by WØGHZ 155miles south of me on 10Ghz tropo. Gary was using a Softrock 10mRxTx as his IF as well, so Softrock to Softrock. My signal can be seen here to be about 6db or so above the noise on Rocky. There was rapid and deep QSB that prevented a QSO. We have however completed a 2-way 10Ghz QSO since where conditions were better while using the 10m Softrock for both transmit and receive. Winter 10Ghz tropo is challenging on this path, whereas during warmer seasons daily QSOs are made with considerable signal margin. We both run 6- 8 watts with 18" DSS dishes and modified DSS feeds at 50+ feet.








Sept 2008 - Ver6.2RxTx gets Frequency Agility!

During the summer, I agreed to do a presentation for Microwave Update on my use of the SoftRocks for VHF/UHF/Microwave IF use. Since the Ver6.2RxTx was no longer available, I purchased a Ver6.3RxTx and ordered the 10m PA/Filter. Sad to say, the 6.3 as of this writing has been unable to meet the FCC specs on 10 meters. The "center frequency" feed-through is only 40db down and must be at least 43db. (Week of Oct 27, 2008 the problem was solved.)I really want to use the Ver6.2RxTx for more than just microwave IF use.

After enjoying the frequency agility of the Ver6.3 I decided to pull the xtal based oscillator out of the 6.2RxTx and replace it with the Xtallv1.1 board that contains a Si570. The Xtallv1.1 frequency selection is determined by a DIP switch. I had Tony custom program the Xtallv1.1 PIC providing better frequency ranges for 2m as well as IF use.













I am using "center" frequencies of 28.119, 28.227 and 28.315MHz. These frequencies allow the continued use for ".100" centered IF applications, as well as center freqs that are suitable for 2m weak signal operations and beacon monitoring. The bit selection for these three frequency ranges were selected to allow the use of a center OFF SPDT switch to select frequency of operation. The PIC contains the freq of operation -- Bit Map. Normally the four gang DIP switch would then be used for frequency selection. Now, one set of contacts of a DPDT switch on the front panel switches the two LSBs and the other set of contacts switches, LED indicators based upon the frequency range selected.

Bit value 1101 - 28.119MHz - Left switch position grounds LSB (144.119)
Bit value 1100 - 28.227MHz - CENTER OFF neither LSBs are grounded(144.227)
Bit value 1110 - 28.315MHz - Right switch position grounds 2nd "LSB"(144.315)







Nov 2008 - Ver6.2RxTx gets "MORE Power"!

I was so pleased with the SoftRock-DEMI Transverter combo, after the expanded frequency provided by the Xtallv1.1, that I am now using it on 2m SSB as well. The DEMI transverter drives a elderly KLM 160W brick very nicely and the signal quality reports have been favorable. This version of the KLM brick does not have a receive preamp, so I use a ARR SP144VDG gasfet preamp and a sequencer that is keyed via a RxTx switch or the mike PTT at the operator position. This combination is very handy for normal tropo range QSOs and gives me a few db over the Icom 746pro. I am using mostly PowerSDR v1.9.0sr40 for SSB/CW.









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