Mike, There is a design problem in this circuit, IMHO, which has to do with tolerances, and I am having an off list discussion about it. Nothing serious, and I am sure that it can be fixed easily. I'm letting you know so that you don't damage anything by too much poking around in K2. The 3.78 volts that you read at U2 pin 5 is 0.053 volts higher, I figure, than you should get with the 7.8 volts from the 8v regulator, if the RP6 resistors are 5100 ohms +- zero!! Three terminal voltage regulators also have tolerance specs on voltage output as measured at the regulator output terminal, so 8.000 volts is not a sacred cow.
I had exactly the same sort of problems, slightly different voltages. But K2 was VERY useable with AGC on, but not quite up to full sensitivity being a little bit "AGC limited". 73, Geoff GM4ESD PS : The low voltage that you get is 2.6 volts - I figure that you should get 2.667 volts - nit pickey fussy eh? ----- Original Message ----- From: "Mike, W8ENG" <[EMAIL PROTECTED]> To: <elecraft@mailman.qth.net> Sent: Wednesday, November 17, 2004 12:44 AM Subject: Re: [Elecraft] Low voltage on AGC threshold > This is an update to my earlier post. I touched up a solder joint and > reassembled the radio. The voltage on pin 5 of U2 was still 3.78 volts, > with the RF gain set fully clockwise. The input voltage from my power > supply was 12.4 volts, both on my DMM and on the K2's internal voltmeter. > The voltage out on the 8v regulator was 7.8,a nd on the 5v regulator was > 4.9. > > I'm thinking that the problem may be low voltage all around. I don't have a > better power supply to check with at a higher voltage. > > Any addational help or comments would be appreciated. > > 73, Mike, W8ENG > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
