[R-390] R-390 Antenna Relay Chatter

Fri Oct 7 16:20:22 EDT 2022

Thanks, Les.  I'm currently "soft-starting" it with an autotransformer and setting it to 115VAC for final run voltage.  I plan to add the thermistor and possibly a bucking circuit as well.

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "Les Locklear" <leslocklear at hotmail.com>
> To: "Jordan Arndt" <Outposter30 at shaw.ca>, "n4buq" <n4buq at knology.net>
> Cc: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Friday, October 7, 2022 3:13:04 PM
> Subject: Re: [R-390] R-390 Antenna Relay Chatter

> Like Jordan said...the voltages are pretty much the same. I would just replace
> it. The few pieces of tube gear I own all have a thermistor and
> am using a bucking transformer to provide 115 Volts AC.
> 
> Les
> 
> 
> ----- Original Message -----
> From: Jordan Arndt <Outposter30 at shaw.ca>
> To: Barry <n4buq at knology.net>, Les Locklear <leslocklear at hotmail.com>
> Cc: R-390 Mailing List <r-390 at mailman.qth.net>
> Sent: 10/7/2022 2:39:55 PM
> Subject: Re: [R-390] R-390 Antenna Relay Chatter
> ________________________________________________________________________________
> 
> 
> 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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