[Elecraft] K2 Noise Solved
A few weeks back I wrote that I was experiencing a most unusual noise problem. I had hoped that someone else might have had the same problem and would have the answer. This didn't happen. The noise was noticeable when the volume control and RF Gain were at minimum and even the antenna disconnected. I want to thank Gary, KI4GGX, who was of great encouragement to me is the solving of this problem. He even suggested I record the noise. I did and sent it to him to hear. I finally decided to use the bruit force approach and used a 1000 UF capacitor with one side grounded. Starting at U9 the audio amp, shorting leads to ground through the capacitor, I discovered the noise was coming in via the CW side tone path. I traced the noise to the input to U 10B pin 5. Under a high intensity light and a magnifying glass, all solder pads looked clean and shiny. Not knowing where else to go, I resoldered all the pins of U10 plus C36. I suspect C36 may have been my problem but all that noise has now gone away. Don Webb...KA7L **Gas prices getting you down? Search AOL Autos for fuel-efficient used cars. (http://autos.aol.com/used?ncid=aolaut000507) ___ 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
Re: [Elecraft] K2 Noise Solved
Don, I have a strong suspicion that the solder pad did not receive enough heat initially. It can happen that the solder looks nice and shiny, but the solder does not have good flow onto the pad. I have seen that condition more times than I would like. It is the result of too low a soldering temperature. A word to potential builders - keep the soldering iron temperature greater than 700 deg F (750 is better). You will not damage anything if the soldering temperature is 800 deg F or below *and* the soldering time is kept short - contrary to popular belief, damage *will* occur with a low iron temperature applied for a long period of time. Also use a small diameter solder so you can control the amount and watch as the thru-hole is heated, it will wick a bit of solder into the hole when it receives adequate heat, but too much applied solder will mask that process and can hide a bad solder joint. 73, Don W3FPR [EMAIL PROTECTED] wrote: A few weeks back I wrote that I was experiencing a most unusual noise problem. I had hoped that someone else might have had the same problem and would have the answer. This didn't happen. The noise was noticeable when the volume control and RF Gain were at minimum and even the antenna disconnected. I want to thank Gary, KI4GGX, who was of great encouragement to me is the solving of this problem. He even suggested I record the noise. I did and sent it to him to hear. I finally decided to use the bruit force approach and used a 1000 UF capacitor with one side grounded. Starting at U9 the audio amp, shorting leads to ground through the capacitor, I discovered the noise was coming in via the CW side tone path. I traced the noise to the input to U 10B pin 5. Under a high intensity light and a magnifying glass, all solder pads looked clean and shiny. Not knowing where else to go, I resoldered all the pins of U10 plus C36. I suspect C36 may have been my problem but all that noise has now gone away. Don Webb...KA7L ___ 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
Re: [Elecraft] K2 Noise Solved
Don: I can't find it now, but I remember a column by Robert A. Pease in which he left a transistor wrapped around the business end of a soldering iron at 700F over the weekend as an experiment and found that its performance specs were still in compliance when he checked it Monday morning. A related issue to tip temperature is that a physically small tip will loose too much heat. There's a happy optimum where the tip possesses sufficient thermal mass to not cool down when applied to the joint, but is sufficiently small for the job. Jack K8ZOA A word to potential builders - keep the soldering iron temperature greater than 700 deg F (750 is better). You will not damage anything if the soldering temperature is 800 deg F or below *and* the soldering time is kept short - contrary to popular belief, damage *will* occur with a low iron temperature applied for a long period of time. Also use a small diameter solder so you can control the amount and watch as the thru-hole is heated, it will wick a bit of solder into the hole when it receives adequate heat, but too much applied solder will mask that process and can hide a bad solder joint. 73, Don W3FPR ___ 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
