[R-390] R-390 Antenna Relay Chatter

[Jim Whartenby]

BarryI would think so, the buzzing is most likely the antenna coil winding vibrating at 120 cycles.  You must have good hearing!
Out of curiosity, what is the AC voltage into the bridge rectifier and the DC voltage output from the new rectifier?  I am assuming that you are using a DVM?  I wonder how your reading will compare with the meters listed in the preliminary manual?
The TS-297 is a AC-DC voltmeter with 1k ohms / voltThe TS-352 a VOM is 1k ohms / volt AC and is either 1k ohms / volt or 20k ohms / volt DC, switch selectableThe TS-505 a VTVM is 20 megohms / volt on most of the DC voltage ranges
I'm sure that since the impedance of this power supply is pretty low the DVM and the three meters above should agree closely but higher impedance circuits should show vastly different readings due to circuit loading.
Regards,Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

-----Original Message-----
From: Barry <n4buq at knology.net>
To: R-390 Mailing List <r-390 at mailman.qth.net>
Sent: Fri, Oct 21, 2022 1:32 pm
Subject: Re: [R-390] R-390 Antenna Relay Chatter

After replacing the selenium rectifier with a full-wave silicon bridge, the antenna relay is no longer chattering.  Truthfully, I'm not certain the chattering was the old rectifier and was, more likely, a failing FL101; however, now that I can power up around FL101, the antenna relay still gives off a distinct buzzing sound.  Since it's being fed a rippled 120Hz DC, is that expected?

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "n4buq" <n4buq at knology.net>
> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Friday, October 7, 2022 11:59:10 AM
> Subject: 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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