As I’m planning some short holiday /P sessions, I’ve ordered 24x 6000 mA (yeah right!) NiMH batteries, a 10W solar panel and an MPPT solar charge controller for my FT-897D on eBay (from China). This evening I was browsing eBay for a second hand QRP tuner and to my great surprised, I saw an auction for a QRP T-circuit tuner kit from Hong Kong China for only $16 with free shipping worldwide option. Incredible! I just couldn’t resist, this is the one I got: www.ebay.com/itm/271357343348.
It’s a typical T-circuit tuner with a 12 position inductor to ground and input / output capacitors. Bonus is a nice SWR dipper tuning aid circuit that helps you tune (LED lights up when SWR is high and dims when SWR is low). I think the circuit is very similar to a product that sells on eBay (also from Hong Kong) for $79.50!! >> www.ebay.com/itm/221204948808
The kit I bought uses a coil wound on a T106-2 toroid, good for around 17.5 uH. The “expensive” ready-made version’s circuit is indicating the bigger T130-2 toroid that has (?!) a lower Al value so only has 14.5 uH with 36 turns. Also, the SWR dipper circuit is slightly different. The transformer for this circuit is wound on a FT37-43 toroid, but my kit has a 2:5 (1:2.5) turn ratio whilst the “commercial” version has 5:20 (1:4). Will try the kit’s circuit, if it doesn’t work, I will experiment with the “commercial” version’s circuit.
I will keep you posted on the kit building progress and the results! Here are some pictures of the kit:
Here are some pictures of the $79.50 “commercial version” of a similar tuner: