[R-390] R-390 Antenna Relay Chatter

Fri Oct 7 16:20:13 EDT 2022

I don't think the B+ will soar in an R-390 because the B+ is regulated. Not
so in the "A" model. That is where I think this issue originated.

The antenna relay is only energized in STBY, BRK IN or CAL. As soon as the
FUNCTION switch is turned to STBY, the B+ comes up.
The B+ will increase only if the regulator circuit develops a problem and
regulation is lost. (R-390)

All of my equipment "sees" ~117VAC due to my BIG bucking transformer.

Regards,
Don WC4G

On Fri, Oct 7, 2022 at 3:40 PM Jordan Arndt <Outposter30 at shaw.ca> wrote:

> I stopped using "Stand By" on all my tube gear because the manner in which
> it is usually implemented allows the B+ voltages to soar, often beyond the
> rated voltages of caps and any other components exposed to the unloaded B+
> voltage.
>
> I also add a CL-90 thermistor in the AC line on all the tube gear I'd like
> to keep running. It drops the input AC by a few volts and provides an
> automatic soft-start. Just make sure there is some air circulation around
> the thermistor and that it's not too close to wiring and other heat
> sensitive parts, because they do give quite a bit of heat.
>
> The 390 and 390A antenna relay circuit is pretty much the same, aside from
> the voltage IIRC, so the rectifier issues are also pretty much the same.
>
> It sounds to me like your rectifier is in the process of failing. What
> happens when you use the Break In circuit...?  Does it chatter when
> operating in Break In mode also..?
>
> 73...Jordan VE6ZT
>
> ----- Original Message -----
> From: "Barry" <n4buq at knology.net>
> To: "Les Locklear" <leslocklear at hotmail.com>
> Cc: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Friday, October 07, 2022 1:08 PM
> Subject: Re: [R-390] R-390 Antenna Relay Chatter
>
>
> > 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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