[R-390] R-390 (non-A) Sudden and New Issue

[Alex Hopper]

Hi folks,

Good news!  I started swapping tubes last night and when I got to the 2nd
mixer tube in the RF module the receiver sprang back to life.  Replacing
the new tube with the same old tube caused the radio to crackle and pop
constantly.

Glad I figured it out, but I have never had a tube fail in such an
“audible” way.

-Alex

Alex Hopper <ahopper0216 at gmail.com> schrieb am Do. 26. Feb. 2026 um 18:00:

> I have attached a video with audio here for reference.
> -Alex
>
> Alex Hopper <ahopper0216 at gmail.com> schrieb am Do. 26. Feb. 2026 um 16:20:
>
>> Could a blown line filter create this constant static popping and zapping
>> noises?
>>
>> I will go back through the records of the restoration to see if this unit
>> was rebuilt.
>> -Alex
>>
>> On Thu, Feb 26, 2026 at 4:18 PM Barry <n4buq at knology.net> wrote:
>>
>>> The line input filter is a small, sealed metal box just in front of the
>>> power connection in the back of the radio.  I rebuilt mine due to a burnout
>>> condition which was not a "fun" project.
>>>
>>> 73,
>>> Barry - N4BUQ
>>>
>>> > Hi Jordan,
>>> >
>>> > This restoration was performed by someone other than me.  Which filter
>>> are
>>> > you referring to on the schematic?
>>> >
>>> > Thank you
>>> > -Alex
>>> >
>>> > On Thu, Feb 26, 2026 at 3:56 PM Jordan Arndt <Outposter30 at shaw.ca>
>>> wrote:
>>> >
>>> >> Out of curiosity, was the AC input filter rebuilt or replaced when it
>>> was
>>> >> restored..?
>>> >>
>>> >> 73...Jordan VE6ZT
>>> >>
>>> >>
>>> >>
>>> >> ----- Original Message -----
>>> >> From: "Alex Hopper" <ahopper0216 at gmail.com>
>>> >> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
>>> >> Sent: Thursday, February 26, 2026 11:46 AM
>>> >> Subject: [R-390] R-390 (non-A) Sudden and New Issue
>>> >>
>>> >>
>>> >> > Hi Folks,
>>> >> >
>>> >> > I have an R-390/URR (non-A model) that was restored by someone last
>>> year
>>> >> -
>>> >> > the individual who restored this set is quite competent and did good
>>> >> work.
>>> >> >
>>> >> > Over the last few days I have noticed 'popping' and 'cracking'
>>> coming
>>> >> from
>>> >> > the set.  Sounds like what you would hear if there was a lightning
>>> strike
>>> >> > nearby, or if there was an internal component that aws arcing.
>>> >> >
>>> >> > As a result the radio does not receive on any bands at the moment.
>>> I
>>> >> took
>>> >> > it out of its cabinet and checked/replugged all the connectors
>>> between
>>> >> > modules.  I fired it up and it worked perfectly normal.  I turned
>>> it off,
>>> >> > put it back in the cabinet and...same issue!  I removed it again
>>> and the
>>> >> > issue persists.
>>> >> >
>>> >> > I don't even know where to start with this, and I am upset that my
>>> >> beloved
>>> >> > R-390 seems to be dead in the water.
>>> >> >
>>> >> > any suggestions or thoughts?
>>> >> >
>>> >> > Thanks,
>>> >> > -Alex
>>> >> > ______________________________________________________________
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>>