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

[Barry]

As they say, it's always the tubes. Glad you found it! 

Barry - N4BUQ 

> 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 < [ mailto:ahopper0216 at gmail.com | 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 < [ mailto:ahopper0216 at gmail.com | 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 < [ mailto:n4buq at knology.net |
>>> 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 < [ mailto:Outposter30 at shaw.ca |
>>>> > 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" < [ mailto:ahopper0216 at gmail.com | ahopper0216 at gmail.com ] >
>>>>>> To: "R-390 Mailing List" < [ mailto:r-390 at mailman.qth.net |
>>>> >> 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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