On Sun, 12 Jan 2020 19:40:23 -0500, Phil Hobbs
wrote:

I'm guessing these spikes are the result of unwanted transient
voltage spikes present on the DC VCO control voltage which sweeps the
RF output frequency from 4Mhz through to 1.3Ghz.

If there's a forest of them, spaced at equal intervals, they could be
coming from a periodic time-domain source.

There *are* equally-spaced spikes at the lower end of the spectrum, up
to about 100Mhz, but thereafter they assume a far more random
appearance - although they are NOT random as they reappear at the same
place on the spectrum and at the same amplitude with each sweep. Plus
there *is*lower-level truly random noise around 500-600Mhz - so looks
like 3 different and unrelated faults to fix!! I do love my vintage
test gear, but I often spend more time fixing it than using it!

Yeah, I'm fonder of analog scopes than JL is, but my beautiful Tek 2467
hasn't been used in quite awhile, whereas I use the 1180x, TDS 694C and
TDS 784As most days that I'm in the lab. For manual driving, the 2467
has the best triggering of the lot, but it's very hard to beat a DSO for
general use.

I only have one DSO out of 13 scopes in all: the Tek 2232. It's
nothing special; it was okay in its day I guess, but I'm sure John's
cheapo Chinese Rigol could **** all over it in a head-to-head
"test-off" lol.
--

No deal? No problem! :-D