[NLRS] DEM 1296 transverter as a signal source

[Gerald]

On Sun, 2005-12-18 at 18:04 -0600, John (JK) Kalenowsky, K9JK wrote:
> 
> Jon and NLRSers,
> 
> Further to Jerry's comments...DEMI also sells a "WSS1152"
> (with various suffix letters) that is based on a 192.005 MHz
> Crystal OR may be specified with the same 192.000 MHz
> Crystal that is used for their 1296 Transverters but the "key"
> is that it produces a signal at 1152 MHz (or plus a little at
> 1152.03 MHz with 6x the 192.005 MHz Crystal and, of
> course, plus/minus actual crystal operating frequency tolerance)
> and the harmonics work out quite conveniently to be around
> the weak signal operating frequencies.
> 
> HMMM...it's almost like someone was looking at that when
> those weak signal operating frequency points were chosen...
> but I'm sure it is JUST coincidence ;-) ;-) ;-).

Not one iota of coincidence. It was PLANNED that way along with 144, 432
and 1296 being harmonics of 144 MHz. Going back further the bands were
1.75, 3.5, 7, 14, 28, 56, and 112 MHz. That was before I was born. There
were the odd bands of 27 and 400 to 401. That 400 to 401 was calculated
to be the resonant frequency of a common copper reflector used in a
popular electrical radiant heater. The computation was erroneous but
that set that band for a while. The frequency was so high for tubes of
the era that it didn't get much use.

For sure amateur microwave operation was based on creating harmonics of
handy frequencies like 1152 back in a time before the microwave spectrum
was assigned.
> 
> UN-fortunately, I believe the actual frequency ranges
> allocated to amateurs at 47 GHz and above are "close" but
> not "in band" compatible with multiplications of 1152 MHz,
> although folks who have equipment functioning up in those
> frequency ranges are probably happy to get whatever they
> can get.

The tradition of harmonic bands has been neglected in the politics of
microwave band allocations of late. There may have been considerations
made for the propagation through water absorption bands. We may have
gotten the short end of the selection leaving better spectra to
commercial interests.
> 
> Happy Holidays to everyone!
> 
> 73, JK

-- 
73, Jerry, K0CQ
Dr. Gerald N. Johnson, electrical engineer
All content copyright, Dr. Gerald N. Johnson