[R-390] Mystery Component

[Jacques Fortin]

Hi Barry,

Eeer... Is that "470 ohms" resistor connected at the same post than the 56K in the picture ??
Where the other end of it is going ?
And if your R560 measures 68K, change it !
It will affect the Carrier Meter calibration and the AGC time constant in "slow" mode.

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 Barry Scott
Envoyé : 13 octobre 2024 23:03
À : Jacques Fortin <jacques.f at videotron.ca>
Cc : R-390 Mailing List <r-390 at mailman.qth.net>
Objet : Re: [R-390] Mystery Component

I'd originally started looking at R560.  It's about 68k in mine.  Not really sure how critical that is and I think at most it might have some effect on the AGC time constant.

I'm pretty sure now, though, that the "mystery" component is a 470 ohm resistor.  Another list member sent a picture of a couple of his IF modules and one is clearly 470 ohms.  That last band is brown instead of orange.  Mine is checking a bit over 500 so probably good enough as-is.  Odd, though, that they used one of the "older" style resistors there.  That's what threw me off more than anything.

Thanks,
Barry - N4BUQ

On Sun, Oct 13, 2024 at 8:41 PM Jacques Fortin <jacques.f at videotron.ca> wrote:
>
> Barry,
> That "mystery" component is R553.
> From your picture, a 1W, 47K ohms, 10% IRC brand resistor (maybe not the original one, but who knows ??).
> It connects the 180V supply to the screen grid of V509.
> R560 (56K ohms) can be seen in the same picture.
>
> 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 Barry Envoyé : 13 octobre 2024 18:15 À : R-390 Mailing List 
> <r-390 at mailman.qth.net> Objet : [R-390] Mystery Component
>
> 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?
>
>
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