Hello group, This might be usefull to all who own the Elecraft T-1 antenna tuner. Some time ago I complained to this group and to the Elecraft support on problems with T-1 had stopped tuning. The answer from the Elecraft Support was quick and extremely usefull! Please find it below! Following their advise I did check the resistance on diodes D1 and D2. It proved something was wrong with the chain of the D1. The diode D1 though turned to be ok . The faulty part was... the capacitor C11 wich was dead shorting the resistor R3 to ground. I replaced the capacitor C11 with a new one ( not SMD by the way, the " normal" one) and bingo! The problems gone , T-1 runs smoothly and quickly . Hope this info is usefull for the T-1 owners and you do have the schematic diagram of the unit in order to better understand the whole thing.
73 de Linas LY2H <<<Elecraft Support: For the tuner to operate, it must see about a 0.5 to 3VDC FWD SWR sensor level (depending on the power level) from diode D1's cathode, and a smaller REFL sensor DC level (higher with more SWR) from D2's cathode - both when you transmit with 1-10w or so of RF from your transmitter. If the 1N5711 diodes are damaged, that won’t happen. If the diodes are OK, there should be about 123K ohms (R3 + R5 or R4 + R6) between each diode cathode and ground when tested with an ohmmeter, with the positive lead on the banded end (cathode) and the negative lead to ground. Bad diodes will have too much reverse leakage in the reverse direction through the diodes and back through R1 or R2 to ground. Then, if your meter has a diode test function, there should be about 0.38 to 0.40VDC of diode drop across the 1N5711 diodes, with the + lead to anode, - lead to the cathode. 1N34A diodes will work in a pinch, but they are not as good as the 1N5711 diodes which should be installed if you need to get them.>>> --------- <<<On Sunday, February 26, 2017 at 1:09:28 PM UTC-7, Linas Balsys wrote: Hello Support, > > My Elecrat T-1 mini-autotuner stopped working after some 10 years of > flawless service... > It started behaving erratically , it either does not react to the RF input > , or if it does then never finds the tune ending up with the red LED on. > It is not related with the antenna type, it is all the same even with the > perfectly tuned R-8 on or a dummy load. Cables are ok. The self LC test > procedure as described in the manual , though went ok. Disconnecting and > re-connecting and replacing the battery doesn' help. I also tried to eject > and reinstal the microprocessor chip to no avail. Visual inspection of the > boards brought nothing suspicious and resoldering the BNC contacts hasn't > made any difference. >>> > > Thanks for your advice! > > 73 de Linas Balsys, LY2H >>>> > > > Sent from my iPad ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
