Re: R4C Sherwood audio mod questions
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Rob, can you send me a link for your presentation? Thanks, Bill N0CU
Hi Paul,
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I was reviewing my 2012 Hamvention Drake Forum presentation and came across a picture of the AMP-4 in my R-4C.? The inverting input has a 220 uF capacitor installed.?
There may well be some AMP-4s with 330 uF capacitors for the inverting input.
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The bulk of the attached Drake presentation deals with drastically reducing the line-related sidebands on the R-4C PTO.? I know you and I found this solution
independently about the same time, likely in 2011.? R-4C owners may find this attached document interesting.?
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It is tedious to rotate the R-4C power transformer 90 degrees, but it really makes a difference.? A hole punch makes the job mechanically easy even if there
is a good bit of work removing and reinstalling the wires.
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We will likely never know why Drake mounted the transformer properly in the R-4, R-4A and R-4B, but mounted it incorrectly in the R-4C.
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73, Rob, NC0B
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From: [email protected] [mailto:[email protected]]
On Behalf Of Paul Christensen via
Sent: Saturday, January 04, 2025 6:52 AM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C Sherwood audio mod questions
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On Sat, Jan 4, 2025 at 05:19 AM, Floyd - K8AC wrote:
>The text specifies the inverting input capacitor as 200 uF while the schematic shows it as 330 uF.
The computed -3 dB high-pass turnover frequency is 123 Hz for 330 uF, and 204 Hz for 200 uF.? Pick either one based on personal roll-off preference.
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