[NLRS] Thoughts on VHF-UHF beacon hardware.

[Doug Reed]

Yup, the older synth rigs were fairly sloppy, but 20PPM was high
accuracy for FM base stations 15 years ago and the mobile rigs were
50PPM. They started using better refs when digital voice, especially
narrow-band voice, became important. The same with ham rigs. In the
last 10 years, they all got better, as did the available refs.

The fact that the old synthesized rigs are not commercial legal
doesn't lesson their value for hams. All those synth rigs less than 15
years old have been a god-send for FM users and repeaters. The issue
with the old crystal rigs is simply the cost of crystals to move them
to "my" frequency. I've been told that a set of "comped and rocked"
channel elements from ICM is over $125 EACH and you need a pair. That
is one reason I am interested in using new synth chips like the
SI5351A/B as a crystal replacement. You can look at all the cheap
computer crystals and such, but you'll seldom find one that gives you
the exact frequency you need for a useful transmitter. But those cheap
generic crystals have been useful for hams, such as building the
filters used in the Minima and PSK-80 Warbler designs.

The older crystal radios usually had good front-end filtering. And
yes, they were usually 2 to 4 MHz wide at 2M. But for the "wideband"
synthesized radios they went to a bandpass filter and up-converted to
solve the image problem. So those rigs tended to be 20-30MHz wide at
2M. That is definitely one of the reasons I still like the old radios
like Mitrek, Micor, Mastr2, and even Motrac, for their helical
front-ends. Pretty much every mobile newer than Delta-S or Syntor-X
have 20MHz wide front-ends so they will work equally well across the
whole band. They are still a little better than similar ham rigs, but
not that much. The high-end commercial FM repeater stations still use
tuned helical front-ends.

For your solar project, look on Ebay for "solar mppt charge
controllers". They have a DC-DC converter on the input and they
auto-adjust to draw maximum power from the panels for charging the
batteries. And they have low-battery monitoring so if the battery
falls below 11.5(?) volts, it will turn off the load. And the battery
has to rise above 12.2 volts to indicate charging before the load will
turn on again. What I'm not sure is if the charger is "quiet" enough
for a RF receive site.

I bought a $10 controller rated for 30 amp load just to play with. The
10 amp and 20 amp models were slightly cheaper. For $30 you can get a
fancier unit with LCD display of voltage and status. Or you can spend
$300 if you want that much build quality. There are a couple places
that sell low-battery cut-outs, but the MPPT controllers with built-in
load shedding are simpler and by far the cheapest......

Good luck with your projects.
73, Doug Reed, N0NAS.