Cobra 142 GTL Mods
radar...@webtv.net
and peaked at cb shop. I want to add talkback and install a mod kit
myself. If you know how please let me know.Also what I want to do is
modify the clarifier and add extra frequencies. I have the mods for
these but it says CT3-USB, L20-LSB and L19-AM may have to be adjusted.
Can I do these adjustments? Another thing what does a 10 kc jumpswitch
do? Thanks for any help you provide.
Mike Yetsko
you
have a schematic for your 142, I'd LOVE to get a copy!! I'm trying to
restore a McKinley that someone was into and buggered up in the
attempt to 'improve' it.
As to the 10khz switch, remember that CB is 40 channels, but in the
space
for 45. The 10KHz switch not only lets you get at those 'extra'
channels
(which are supposed to be for remote control, but it turns out some
low power FM voice is there too as well) and to go beyond channel
40 (the freebanders). Both of which are very illegal. It's technically
an
easy mod since the PLL uses 'numbers' to figure out the channel.
I don't know the actual numbers offhand, but it's SORTA like CB channels
1-2-3-4-5-6 using the numbers of 1-2-3-5-6-7 in the PLL. Notice that
the
PLL skipped '4'? Well, that's one of the 'skipped' channels. And CB
There are holes between 3-4, 7-8, 11-12, 15-16, and 19-20. And the
channels aren't all in order, there USED to be two channels between
22 and 23, but now in frequency order the channels go like this:
21-22-24-25-23-26-27.
As to the other 'big' mod, that's the clarifier. That mod comes in two
flavors. On CB sets the TX is locked and the RX shifts with the
clarifier.
This is actually best when two people talk, but what about three? The
clarifier is easy to 'unlock' so that it shifts both TX and RX, and when
correctly adjusted, the RX and TX will track exactly with each other.
The other flavor is a 'slider'. This is just extending the range of the
clarifier so that instead of going up and down maybe 1000 cycles, it
goes 2000 or even as much as 4000hz. But the problems here are
twofold. One is that the clarifier knob is now so touchy as to make it
almost totally worthless for mobile use. But that can be solved by
replacing the regular potentiometer with a multi-turn unit. The other
is
that it still is touchy, and most rigs modified this way sound like...
well,
they sound like shit on the air, but you'll never convince these '*"
operators that their rigs aren't the best thing since sliced bread.
Especialy since they probably paid some guy $50 to do something
that a hacker can do in 5 minutes with NO parts cost. And most of those
5 minutes are taking the radio apart and putting it back together!
If you do anything with the clarifier, the reference voltage must be
CLEAN AND STABLE!! I can't stress that enough. Unfortunately most
of the idiots who mod the sets don't understand that at all.
The adjustments you mention should be possible for a home hobiest
to do (although illegal) if you have the right tools. On the RS uPD858
rigs the spec is to set the internal reference frequencies to 20Hz for
the three crystals in the main PLL section and then to 5hz for the two
secondary crystals. If you have equipment that can ACCURATELY
get you there, well, then you theoretically could do it.
As to the chassis in the Cobra 142? I don't know, I'm still trying to
find
a schematic (I've been told it's the same as the McKinley if you have
the 142GTL that uses the 8719 PLL).
Mike
<radar...@webtv.net> wrote in message
news:10933-38...@newsd-612.iap.bryant.webtv.net...
ManX
A or rc chanesl and chanel 41.