[Heathkit] Signal on 28.635 MHz

[Gregory W. Moore]

GE, All.

Jim, you are 100 Percent right on the colorburst harmonic. Today's TV's 
are very poorly shielded compared to what
used to be around.  Zeniths are some of the worst offenders. Not the 
good old Made in USA models, but the modern imports.
The one in my living room at this moment has an extremely disturbing 
tendency to brute force overload on anything over about
35W out on just about any frequency you can imagine, and this is on CH4, 
downstream from the ubiquitous digital cable converter. (Yes, I could go 
straight baseband, but since I only have one input, that is used for 
DVD--hi-- 
 In addition, do you remember there used to be a lot of circuitry around 
for station clocks that synched to colorburst?.  They used a tuner to 
tune the local VHF station, and
synched with their colorburst freq.  This always was pretty accurate, as 
all the VTR/VCR's output colorburst regardless of
the signal was black and white or color, if a signal was black/white, 
there simply wasn't any chromanance info.  This was
especially true of Betacam, which pretty much was the gold standard of 
broadcasting/ENG along with, of course, 1". It even was used back in the 
halcyon days of 2" tape (love that magnetic developer when "editing"")

I do believe I have a digital clock somewhere in ye olde junque boxe 
which I built  on nights while standing Engineering for
a major channel which shall remain nameless to protect the guilty.  The 
unit was quite accurate for it's time, and I may bring it back, seeing 
as how the NIST synch clock I now have is being wiped by 60 Hz 
interference, which I am working to locate
When one lives in a row house, and that works out to about 80-90 poor 
service connections, as well as a remote reading meter system, of which 
I still am trying to get the dope, and a neighbor who has something (I 
believe it's either a doorbell transformer, a furnace transformer, a 
florescent ballast, which is radiating like a small pulsar, and they are 
NEVER home, it's rough.)

Being retired disabled helps, I have all the time in the world to ferret 
out these pesky problems... I will, however, go with the colorburst 
signal.  Modern sets, being all of the throwaway type, are some of the 
worst offenders for short range transmission I have seen.  I'm trying to 
remember what else used a colorburst xtal that used to be 
around....darn, I am wondering if these remote reading electric meters 
might not use cheap 3.58 burst xtals as a timebase, to save bucks. It's 
not like they have to have a lot of memory, or be fast, or even that 
complex....I would make book that the guiding parameters were A. Cheap  
B. Cheap
C. Fail on High Reading D. Cheap.

73 de Greg "GW" Moore WA3IVX/NNN0BVN


Jim Shorney wrote:

>Glen,
>
>IMO, you're probably looking at a TV colorburst harmonic. Colorburst
>crystals are used as the master oscillator in a surprising number of
>devices. The 8th harmonic of 3.579545 MHz is 28.63636 MHz. If your
>signal is real close to that frequency and doesn't vary, it may be
>coming from a TV set or VCR. If it wanders around a bit, it is coming
>from something else that uses a colorburst crystal.
>
>73
>
>Jim
>
>
>
>On Mon, 3 Jan 2005 14:45:11 -0800 (PST), Glen Zook wrote:
>
>  
>
>>Last night I was checking a local's SSB signal on the
>>10 meter band.  After we got through I started tuning
>>around the band and ran across a steady carrier
>>located approximately at 28.635 MHz.  Although there
>>are numerous computer "spurs" around that frequency
>>this particular signal is very different from the
>>"normal" computer spurs.
>>
>>Anyway, I haven't put my 10 meter mobile in the car
>>and gone looking for the source of the signal. 
>>However, I am looking for suggestions as to just what
>>this might be.  Frankly, over the years I have run
>>into all sorts of signal sources.  But, none as
>>"clean" as this particular source.
>>    
>>
>
>
>  
>


-- 

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