"Eric Greenwell" wrote in message ...
On 10/3/2012 1:42 PM, wrote:
Our club just purchased an ASK13 with a RST 542 installed. Unit is
working great and we just need to add appropriate TX and RX crystals
for 122.9 and 122.975. Jim at RST Engineering has been zero help.
When I call him he just rants that "Jan Crystals" has the specs and
wants me to only correspond via email with him. Of course he does
nothing via email except denegrade me for not asking the right
quesions of "Jans Crystals". "Jans" is more than willing to
fabricate the proper crystals but they need to know 1) Pf Load 2)
Ohms 3) Tolerance. Can anyone on this forum supply me with the
above info? I would greatly appreciate it as I have reached a
complete dead end with Mr. Jim of RST.

Is this radio still legal?

Lane,

Typically this type of a units have a frequency tripler circuit. If that is
the case the crystal is cut at 1/3 the output frequency. To find out check
frequency of the 122.8 crystal to see is 40.933. If it is, the tolerance is
only 0.001%. (10 parts per million.) If it is a 122.8 crystal the tolerance
is 0.003%

It has been too long since my electronics classes (50+ years) for me to be
able to derive the Pf Load and Ohms from the schematic diagram.
http://www.rst-engr.com/rst/support/RST-542.pdf

I'm sorry that I can't be more helpful.

Eric,

The simple answer to your question is "No". As of Jan 1, 1997 aircraft
radios must be type certified. The frequency accuracy to meet the 25 Khz
channel spacing is 0.003%. Commercially built radios such as the Genave
Alpha series are no longer legal. The RST-542 and Genave are similar in
design. Radios built today have a sticker indicating that they are FCC
certified.

Wayne