[R-390] Mystery Component

Mon Oct 14 02:45:38 EDT 2024

Jacques-
the only place it was found it was in some document listing it as 470 
ohms ( a friend in Docs found it by accident looking for something else 
for me) , all the units I examined were 470 ohms. ( both physically and 
visually), I wish i had the proof....but alas the document(s) could not 
leave the facility.
I have no idea why, I just took it as verified with so many units with 
470  ohm, I move on.....
I do not know why it was not properly documented.
now that is the mystery! We have access to more info today.....so sleuth 
away...
I quit looking as I had other things more important on my plate...btw 
this was ~25 maybe more yrs ago.
Renée

On 10/13/24 8:45 PM, Jacques Fortin wrote:
> Wow, hold it !
> Renée, R554 is 2.2k ohms in the part list !
> Why do you state it have to be 470 ohms ?
> There is a published modification order for that ??
>
> 73, Jacques, VE2JFE in Montreal
>
> -----Message d'origine-----
> De : r-390-bounces at mailman.qth.net <r-390-bounces at mailman.qth.net> De la part de Renee K6FSB
> Envoyé : 13 octobre 2024 23:13
> À : Barry <n4buq at knology.net>; R390A List <R-390 at mailman.qth.net>
> Objet : Re: [R-390] Mystery Component
>
> this should settle the mystery  470 Ohm 1W ..I however do not know why the schematics show 2.2K unless a different tube was used ie 6ba6 or 6au6.. at some point in the past Renée
>
> On 10/13/24 7:57 PM, Renee K6FSB wrote:
>> oh R553 is 47K 1/2W all the way at the bottom...umm top?  hard to see
>> - next to chassis and  connected to G2 then to B+ Renée
>>
>> On 10/13/24 7:48 PM, Renee K6FSB wrote:
>>> it is a 1 W resistor.....old style molded.....most likely what was in
>>> stock......
>>> I just pulled my 390 deck....all the pictures I saw it appeared to be
>>> brown..however I could be wrong! the 6 decks I measured was ~500 ohms
>>> I just lifted mine yep looks maybe ORAnge or Brown...more brown...1w
>>> Thanks for making me look again Real hard.....to verify The meter I
>>> am using says 0.474K . if it was 47K or 470K the AGC would not work
>>> at all, I still think Brown especially for a 6JB6...that makes sense
>>> anything else no.
>>> i have been following you and AGC issues and no matter your agc is
>>> not working so put in a 470 Ohm 1W make sure Z503 is good and not
>>> open fried.
>>> 500K is pretty much open for that application.
>>> plate voltage would be way too low if R is too high and no AGC action.
>>> Renée
>>>
>>>
>>> On 10/13/24 6:46 PM, Barry wrote:
>>>> I measures just a bit over 500k.  I'm pretty sure it's yellow,
>>>> violet, orange.  I just don't get why it's a molded style like that.
>>>> There doesn't, though, appear to be a 2.2k between it and Z503.
>>>>
>>>> Thanks,
>>>> Barry - N4BUQ
>>>>
>>>> --------------------------------------------------------------------
>>>> ----
>>>>
>>>>      *From: *"Renee K6FSB" <k6fsb.1 at gmail.com>
>>>>      *To: *"Barry" <n4buq at knology.net>
>>>>      *Sent: *Sunday, October 13, 2024 7:46:12 PM
>>>>      *Subject: *Re: [R-390] Mystery Component
>>>>
>>>>      looking close at the picture (btw your picture is in the AGC
>>>>      area) it IS a 470 ohm resistor and IS R554. one side to B+ the
>>>>      other side to Z503...just like mine.....I did a lot of research
>>>>      looking at IF decks and the R554 is 470 for R390....for the A it
>>>>      is 2.2K
>>>>      put a meter across it....and in My schematics shows 2.2K which
>>>>      is incorrect.. all the units I have seen it is 470 Ohms per
>>>>      chassis visuals about 25 units...
>>>>      Note R390 IF Schematics are wrong shows 2.2K....btw mine
>>>>      measures 474 Ohms
>>>>      you are over thinking this it is fine. just an older style
>>>>      molded R,  Yel Vi Brn 10%
>>>>      Renée
>>>>
>>>>      On 10/13/24 4:50 PM, Barry wrote:
>>>>
>>>>          Hmm.  I could see it could be a 47k (last stripe being
>>>>          orange but it's kind of hard to see much of the stripe to
>>>>          tell for sure).  If so, then its likely R553; however, if
>>>>          that's the case, then R554 seems to be missing (or I just
>>>>          can't see it).
>>>>
>>>>          Thanks,
>>>>          Barry - N4BUQ
>>>>
>>>>              That is a 470 Ohm resistor same as in the AGC B+ circuit.
>>>>              Renée
>>>>
>>>>              On 10/13/24 3:14 PM, Barry wrote:
>>>>
>>>>                  Maybe not really a “mystery” but I can’t identify the dark brown cylinder with one yellow and two brown(?) stripes in the AGC time-constant compartment in my R-490/URR. A 410-ohm resistor?
>>>>
>>>>                  If those are actually violet stripes then I’m even more confused.  Anyone know?
>>>>
>>>>
>>>>                  Thanks,
>>>>                  Barry
>>>>
>>>>
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>>>>
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