... from a person with quarter century In QC department - there's special kind of "aggressive" washes specifically designed to penetrate coating and provide acceptable electrically ground connection.
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-----Original Message-----
From:
[email protected] <
[email protected]> On Behalf Of Bob Wolbert, K6XX
Sent: Monday, July 18, 2022 13:46
To:
[email protected]Subject: Re: [yccc-so2r] RFI Into Mic Line
Paul, Dennis,
Thank you for replying.
For background, I just received and built this (old stock) kit. "Run 4"
is a quote from Dennis's email of 24 Oct 2011 warning about a floating ground on the audio amp that required a shorting jumper to connect them that affects the fourth run of PC boards. A printout of this message was included with the kit. Nothing to do with a K4... radio was mentioned to explain why multiple mic preamps were available.
While I scraped the tenacious powder coat off the ground stud, I missed the part about scraping paint where the board mounts. My mistake!
An ohmmeter shows no continuity between the various connector shields themselves, or between them and chassis. I will run a shorting wire to all of these as well as scrape away more paint. I calculate that about 0.01uF is a good starting point for a bypass capacitor across MIC and MIC GND.
I appreciate your assistance!
In the "No Good Deed Goes Unpunished" department: a comment to any of you crazy enough to consider a similar future product. From direct personal experience, it is unwise to pay chassis fabricators to powder coat the interior of RF-system boxes. While much more attractive and 'professional looking', the paint really gets in the way, even as overspray. In fact, it _is_ wise to pay them to mask the interior of the box where grounded connectors mount, even when the insides are not painted. Now, off my soapbox and on to cleaning up my new SO2R box!
73 de Bob, K6XX
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73 de Bob, K6XX
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73 de Bob, K6XX
