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Title: Help with Ranger audio.... Post by: kx9dk on December 20, 2005, 05:18:45 PM Recently aquired an early Ranger (version without bias and keyer tubes). Unit was pretty well hacked up. Looked like someone tried to modify audio section and then gave up. The driver transformer was missing and numerous wires disconnected.
I solid stated the power supplies and used a Ranger modification circuit I found on the AMWindow site as a guide to get the audio section rebuilt. http://www.amwindow.org/tech/htm/rangmod.htm I got the RF section working, but having trouble with the audio. Can anyone tell me from the images below where I might be having problems? The images start with an unmodulated carrier then audio gain increases up to about mid rotation of gain control. (http://www.davidkoch.info/miscpages/dave/acarrier1.jpg) Carrier (http://www.davidkoch.info/miscpages/dave/amod1.jpg) AM1 (http://www.davidkoch.info/miscpages/dave/amod2.jpg) AM2 (http://www.davidkoch.info/miscpages/dave/amod3.jpg) AM3 Looking forward to getting back on AM Thanks, Dave KX9DK Title: Re: Help with Ranger audio.... Post by: Steve - WB3HUZ on December 20, 2005, 06:41:26 PM There's some serious cross-over distortion on there. What is the modulating frequency?
Title: Re: Help with Ranger audio.... Post by: WA1HZK on December 20, 2005, 08:49:33 PM Take a look here:
http://amfone.net/ECSound/HZKRANGER.html However you do this start at the input with a 1000 cycle tone. Nice clean sine wave. Check each stage from the mic. input back until you find the section that is screwing up. Seek & Destroy! Keith Title: Re: Help with Ranger audio.... Post by: kx9dk on December 21, 2005, 10:07:55 AM Thanks for the replies. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
It's been 40 years since I last used AM and need a little refresher training. the patterns above came from the 1575 tone generated in a SM-220 station monitor. I plan to use a D-104 once I get the audio working. Thanks KX9DK Dave |