[R-390] R-390 Antenna Relay Chatter

[Barry]

Hi Les, 

That advice appears to pertain to an R390A. This is an R390. Do you think that would make any difference? 

BTW, I was using STANDBY primarily for warmup. 

Thanks, 
Barry - N4BUQ 

> From: "Les Locklear" <leslocklear at hotmail.com>
> To: "David Wise" <d44617665 at hotmail.com>, "n4buq" <n4buq at knology.net>, "R-390
> Mailing List" <r-390 at mailman.qth.net>
> Sent: Friday, October 7, 2022 12:33:17 PM
> Subject: Re: R-390 Antenna Relay Chatter

> From the "Archives"

> DO NOT use the "STANDBY" position on the FUNCTION switch. The now unloaded
> stages will cause the various voltages in the receiver to rise upwards perhaps
> beyond the tolerances of some critical components. This is caused by the
> multiplicity error in our sometimes 120v+ line voltage v/s the 115v in use when
> the 390A was designed and built. Since it is normal for the "LOCAL GAIN"
> control to not completely mute the audio when turned down fully, it is natural
> to consider putting the receiver in "STANDBY." Remember, DON'T. Instead, turn
> the audio down and also back off the RF GAIN control to about 11 o'clock and
> the residual audio will disappear and no damage will be done to the receiver.

> Les Locklear

> From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> on behalf of
> David Wise <d44617665 at hotmail.com>
> Sent: Friday, October 7, 2022 12:12 PM
> To: Barry <n4buq at knology.net>; R-390 Mailing List <r-390 at mailman.qth.net>
> Subject: Re: [R-390] R-390 Antenna Relay Chatter
> Should not chatter. #1 suspect is CR801; selenium rectifiers have a notorious
> habit of increasing forward resistance as they age. Convert to silicon plus a
> resistor in series to mimic the natural forward resistance of new selenium. (I
> don't know what that value should be.) This is what Tektronix did with their
> oscilloscopes; for every selenium-powered model, they created a silicon
> retrofit kit. One of my scopes has one.

> Or you can add a reservoir capacitor, starting small and increasing until the
> chatter is reliably gone at low mains voltage. I am using 100uF. Upside is
> potentially reduced hum. Downside is that CR801 will continue to deteriorate,
> so eventually the problem will recur.

> HTH,
> Dave Wise
> SWL (inactive)
> ________________________________
> From: r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> on behalf of
> Barry <n4buq at knology.net>
> Sent: Friday, October 7, 2022 9:59 AM
> To: R-390 Mailing List <r-390 at mailman.qth.net>
> Subject: [R-390] R-390 Antenna Relay Chatter

> When in STANDBY, the antenna relay in my R-390 produces a bit of chatter. Is
> this normal? I see where that relay is fed, unfiltered, from CR801 which, from
> the pictures in the manual, appear to be a stack of selenium diodes and I'm
> wondering if that rectifier stack might be a problem. Anyone know what to
> expect from that relay in STANDBY and, perhaps, what I'm seeing might be
> normal?

> Thanks,
> Barry - N4BUQ
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