SA2CLC radio stuff

 The power supply is essentially a vibrator power supply, but with an IC and mosfet instead of the mechanichal vibrator used in the old days. The schematic can be seen below: It´s actually quite straight forward:  The CD4047 is operated as an astable multivibrator, providing two , out of ohase, square waves, driving the gates of the FET´s. The FET´s ground one end of the transformer winding, causing current flow, and induces voltage to the secondary winding (which in this case in the old primary) Switching frequency is determined by capacitor C3 and resistor R4. These values in the schematic gives approx. 50Hz switching frequency.  Optional 28V operation: I included holes on the board to hold a zener diode at the input of the CD4047 (max vcc 18v) in case 28v operation would be used (non-modified filament strings). A different transformer is also needed. There is a transformer that fits the board, 14A-10R-36, by the number we can tell that it´s a centertapped 36v seco...

 I have been hosting a class called "Repairing your first boatanchor" over at LICW ( The Long Island CW Club) over the last 2 or three months, where I have recapped, measured and fixed an old SCR-274 BC455 40m receiver during online classes. One issue with these receivers is powering them. Originally they were powered by dynamotors (motor generators) but these are hard to come by here in Sweden, so I wanted to design a power supply that could be used in place of the original dynamotor. The result is seen below. Using a CD4047 as an astable multivibrator, driving a 10W pcb transformer backwards, gives us the needed ~ 200V for the receiver. after running the receiver for close to one hour, I must say I´m pleased with how this turned out. More details to follow. //Tommy, SA2CLC

    With the 3Y0J dxpedition on air, and 30m being used alot, I did what I could to get a qso.  I have an inverted vee, fed with ladderline and a link tuner, which tunes on 30, but I wanted to try something a bit more directive. Settled for 2 phased verticals which turned out nice. Had 2 identical 6m fishing rods, which were extended using military surplus tent poles (Nato stuff). Had made a bunch of the ground plates at my last job, so it was a quick job throwing the antennas together. Used 2 elevated radial per vertical and used christmann phasing. The nano vna was very useful when cutting the feed and delay lines. Here´s a link to  the VA7ST pahsing line calculator. www.va7st.ca/christman phasing Tests with a nearby station showed approx 10db stronger signal than compared to the vee. RBN spots showed around 6db in favour of the phased verticals over the vee. This antenna might be a keeper. So, what about 3Y0J. No qso yet, but my hopes are still up. //SA2CLC