"Steve Kavanagh" wrote in message
om...
A year or so ago I was working on a microwave local oscillator (at
about 2.5 GHz) multiplied up from a crystal oscillator near 40 MHz.
The output was found to jump in frequency by tens or hundreds of Hz
many times as the LO chain was warming up. I was able to reduce this
jumping by replacing all the dipped silver mica capacitors [...snip]

The capacitors used in both cases are from unknown sources and were
probably manufactured in the early 1980's.
Has anyone else experienced this behaviour ?
Steve (VE3SMA)

Steve,
Although I didn't figure it out at the time, my Knight-Kit Space Spanner
circa 1960 had terrible microphonics - very noisy. I cleaned the entire
chassis & rewired it to no avail. Today I suspect a mica cap, the old
square type, since I heard of same thing this some time ago.

Space Spanner.. O'Man, I could only afford the Ocean Hopper.. Man, them
were the days!

Joel AG4QC

"Steve Nosko" wrote in message
...

Steve,
Although I didn't figure it out at the time, my Knight-Kit Space
Spanner
circa 1960 had terrible microphonics - very noisy. I cleaned the entire
chassis & rewired it to no avail. Today I suspect a mica cap, the old
square type, since I heard of same thing this some time ago.

"Joel" wrote in message
...
That "Steve Nosko" wrote in message
...

Steve,
Although I didn't figure it out at the time, my Knight-Kit Space
Spanner
circa 1960 had terrible microphonics - very noisy. I cleaned the entire
chassis & rewired it to no avail. Today I suspect a mica cap, the old
square type, since I heard of same thing this some time ago.


Space Spanner.. O'Man, I could only afford the Ocean Hopper.. Man, them
were the days!

Joel AG4QC


Yea! AND, get this, I think I took plates off, or bent some, of the
bandspread cap to reduce its range and calibrated it for 40 M. Every
Saturday morning I'd listen to the same group on SSB talking about their
Collins rigs and inverted Vees.
Wish I still had it and the Knight-Kit crystal set. Had it hooked up to
a loud speaker in my room (course I was in Wood Dale, IL., not too far from
the WBBM and WGN AM transmitters...)
73
--
Steve N, K,9;d, c. i My email has no u's.

"Joel" wrote in message
...
That "Steve Nosko" wrote in message
...

Steve,
Although I didn't figure it out at the time, my Knight-Kit Space
Spanner
circa 1960 had terrible microphonics - very noisy. I cleaned the entire
chassis & rewired it to no avail. Today I suspect a mica cap, the old
square type, since I heard of same thing this some time ago.


Space Spanner.. O'Man, I could only afford the Ocean Hopper.. Man, them
were the days!

Joel AG4QC


Yea! AND, get this, I think I took plates off, or bent some, of the
bandspread cap to reduce its range and calibrated it for 40 M. Every
Saturday morning I'd listen to the same group on SSB talking about their
Collins rigs and inverted Vees.
Wish I still had it and the Knight-Kit crystal set. Had it hooked up to
a loud speaker in my room (course I was in Wood Dale, IL., not too far from
the WBBM and WGN AM transmitters...)
73
--
Steve N, K,9;d, c. i My email has no u's.

Space Spanner.. O'Man, I could only afford the Ocean Hopper.. Man, them
were the days!

Joel AG4QC

"Steve Nosko" wrote in message
...

Steve,
Although I didn't figure it out at the time, my Knight-Kit Space
Spanner
circa 1960 had terrible microphonics - very noisy. I cleaned the entire
chassis & rewired it to no avail. Today I suspect a mica cap, the old
square type, since I heard of same thing this some time ago.