Jacques,
I will wait and install the newcapacitor and give this a try. I will also keep
the old unit if it isneeded. I will look to see how the performance curves
look for the new and old capacitors.
Measuring down to 10nA is not acurrent capability (no pun intended). From the
information you areproviding, it sounds like the "older style mica caps within
the IFtransformers that are not the newer Micamold style should be replaced
with theMicamold style or a new high Q mica cap. I will review each of the
internal components to assess what type ofcapacitor is located within each
unit. I extend a thank you for sharing thisrather interesting information, as
it helps advance my understanding of care forthis receiver. This RF sub
chassis is from TeledyneSystems Corporation, serial 7099 within a receiver by
Imperial Electronics, Serial2901.
73John N3JKE
On Friday, June 28, 2024, 4:07:34 PM EDT, Barry <[email protected]> wrote:
I just opened the Y2K-R3 document and on page 6-47, Figure 6-21 shows a
picture of C327 which appears to be a ceramic disc. Is that a mistake in the
Y2K documentation? Apologies if this has already been discussed but I found it
odd in light of all this recent conversation regarding C327.
Thanks,
Barry - N4BUQ
> John, unless that you are equipped to test the Micamold cap with 300Vdc
> applied
> (their manufacturing voltage rating) to confirm that they have less than 10nA
> of leakage, wait for the new manufacture 1kV one.
>
> I believe that the recommendation to change C327 was made because of the
> trouble
> involved with the RF deck removal to change any of the parts within.
> Since then, many original mica caps inside the IF transformers were reported
> to
> fail (the thunderstorm noise problem).
> But here also, they will not ALL exhibit failures, as this is just a
> probability.
> Failure of the early type "postage stamp" mica caps is essentially due to
> their
> long-term casing permeability.
> Some mica caps were made to never fail, like the Corning Glass Works (CGW)
> ones
> that have a glass encapsulation.
> But as with any electronic equipment ever made, all depended on the cost vs
> reliability criteria.
>
> 73, Jacques, VE2JFE in Montreal
>
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