Another 10m QRP transceiver built

Yesterday I built another simple 10m CW QRP transceiver. This is similar to the Tenner on my website with some improvements. This time the power out is QRO (well 600mW!) and the receiver a direct conversion one built around an SBL1 with passive LP audio filter and 3 stages of audio gain. The VXO, run from a regulated 5V supply, uses a fundamental 28.060MHz crystal which pulls from 28.040-28.070MHz with a sensible RX-TX offset (happens automatically) of around 800-1000Hz. Chirp is better than the simple XBM10-2 as the VXO is better regulated and the PA is a separate stage. Yesterday I worked RZ3QZ before the RX was finished and got reports on the reverse beacon network from W3OA. This morning a full 2-way QSO with UR5IDU (him 579 me 549).

UPDATE 1520z Nov 5th: This rig is working very well with 7 two-way QSOs on 10m CW in the log already since 1140z today. There is a Russian contest and the band is busy with Russian stations. Reports are all 599 of course but no repeats needed so far.

VLF up-converters and MOSFETs

Today I built a MOSFET up-converter, converting 7-9kHz VLF to around 20MHz. However, I was disappointed with the results: low conversion gain and sensitivity when using either a 3N211 and a BF981 device. I used an 82mH choke with a 4n7 cap as the tuned circuit on G1 (tapped capacitance for max sensitivity with 50 ohm input) with LO injection on G2. Despite optimising everything I couldn't better the sensitivity achieved with the SBL1 based up-converter that appears on my website.