I've been gathering up and organizing parts for my DMTD project, and
also am revisiting my differential frequency counter that will go with
it. I had started the counter project years ago, and had most of the big
stuff mounted and ready to start building. This was to be a cascade of
frequency multipliers a la the old Tracor (527, I think) frequency-phase
meters, but using microwave frequencies for higher multiplication
factors. Each stage was to take 10 MHz in, and make 1 GHz out, so 100x
the frequency deviation against the reference channel.
While looking for project stuff, I rediscovered a bunch of 4.7-5.2 GHz
PLOs I had, and my notes from way back, where I considered them as
alternates to the 1 GHz ones. I decided to finally resolve which setup
to use, and rigged up a quickie 500x frequency multiplier. I found that
these 5 GHz PLOs are remarkably stable, and actually seem to prefer a
reference in the 10-20 MHz range, whereas the 1 GHz ones were apparently
made for a higher range, and were not as good in this respect, with 10 MHz.
The more I look at these 5 GHz PLOs, the more I like them. They are
built for 24 VDC, but I've been running them at 20, and they seem fine.
They are beasts on power output - around +18 to 20 dBm, I'm guessing.
Imagine what they would do at full supply voltage. They are of the power
oscillator/SRD multiplier/BPF variety, so the oscillator direct-drives
the SRD. Imagine the RF VA level in the 1250 MHz cavity required, to tap
off only a little bit of power to multiply four times, and deliver +20
dBm. I think this high power also helps with the stability, since
there's plenty available to grab a little for the PLL sampler.
I have about a dozen of these puppies, with about seven tested OK so
far, and the rest with problems that need fixing. I only need three to
make a two-stage multiplier up to 500 x 500x, so have plenty of spares.
Since I'm moving everything up from the original plan, I need to use 5
GHz mixers. I have a bunch of MC24P and MC36P SMA mixers that I know are
around the right range - most came from the same junked microwave gear
as the PLOs. I've used these in a number of projects over the years,
guessing that the part number may indicate the frequency range, as with
many other RF parts. I have typically used the MC24P in 2-4 GHz
applications, and the MC36P for 3-6 GHz, or even wider, and they have
usually worked just fine.
In this application, I'd like to optimize drive power, and know the real
specs, to get the best possible S/N ratio. I vaguely recall that I had
once found the data sheet for one or both, many years ago, but can't
find them any more, or online. There are lots of them for sale out
there, so they must have been very common, but apparently there are no
data sheets or cross references that I could find.
These units are marked Magnum Microwave brand, now owned by API
Technologies. Their website denies that these exist, so I guess the
parts and data are long gone. Looking at the one thing I could find
there seemingly even slightly related, is their MC3XMS-3, which is in
the 5-6 GHz range. The "MS-3" is the micro-strip package form, and a "6"
in the X position means +13 dBm LO. If the same codes apply to the old
parts, and if the P suffix means SMA connectorized, then MC36P might be
a 6 GHz class, level 13 mixer, which could be about right. Or not.
For reference, here's that datasheet:
http://67.225.133.110/~gbpprorg/mil/xband/MC3XMS-3_-14.pdf
Anyway, I'd like to find an actual datasheet for each of these mixers,
especially right now, for the MC36P. I'd like to drive them as high as
possible, but not risk damage. These PLOs have plenty enough juice to
blow them out, if I get carried away or make a mistake, or don't know
the mixer specs and guess wrongly. In my present experiments, I've been
running about +10 dBm into both the LO and RF ports, so +13 altogether,
which seems safe, and has been working nicely.
If anyone has any info on these parts, I'd sure appreciate it. An old
Magnum Microwave catalog from the 1980s would probably have it.
Ed
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