Looking for one or two working STC STR8212 HF receivers to purchase. I have three working units (s/n 121, 132 and 133) and another cannibalized parts unit (104) and use the working units in a public spotting station for digital FT8 transmissions on 20, 30 and 40 meters. I would like to add a 15 meter receiver and have a backup unit. Dave Twyver K7DAT