Title: Weird Ranger Problem Post by: W3UTD on February 14, 2010, 11:23:09 AM Finally got the rig on the air, and found something strange quite by accident. When I grabbed the mike (D104) I accidentally tapped the head against a shelf, and I heard started some sort of buzz from the right side near the 1614's. I can also hear it coming from the mic element, and the meter (in Mod position) pegs at 140
If I rotate the Audio control back to zero, then up again, it goes away and resting Modulation is back to about 60. I can talk and whistle etc with no problem, but a tap or a loud clap and off it goes again. And it happens in both VFO and crystal positions. I've looked for grounds or shorts back through the mic wiring but nothing yet. Any ideas? Title: Re: Weird Ranger Problem Post by: WQ9E on February 14, 2010, 11:45:36 AM Sounds like instability somewhere in the audio chain. Is the Ranger stock or has the audio been modified? Is this happening into a dummy load or only when connected to the antenna?
Title: Re: Weird Ranger Problem Post by: W3UTD on February 14, 2010, 01:41:42 PM It happens on both antenna and dummy load.
To the best of my knowledge, it is stock, but most of the larger electrolytic caps had been replaced. The only things I can think of, audio related, that are different from a bone stock ranger are: C52 (500pf) replaced with .02uf C53 (200pf) was gone when I got the rig, but I didn't put it back C59A/B (15uf ea.) replaced with 22uf each C50B (10uf) was a straight replacement, but C50A (also 10uf, which should parallel C54) was not there, so I did put it back. Maybe there was a mod that removed C50A at some point? Title: Re: Weird Ranger Problem Post by: WQ9E on February 14, 2010, 02:44:45 PM It looks like the following was done to your rig: http://www.amwindow.org/tech/htm/ranger.htm
Somebody who has done the mod is going to need to chime in because mine are both stock so I am not sure how the modified circuit behaves. Title: Re: Weird Ranger Problem Post by: W3UTD on February 14, 2010, 04:24:19 PM Rodger, you're "da man" again. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
I backed out my replacement of C50A, then did what the warning suggested "0.005 across the driver transformer with a 0.001" Bingo! |