Cobra 148GTL on 10 Meters?

[Ken Collier]

Does anyone have any experience modifying a Cobra 148 GTL CB radio for
10M ham use? I know it can be done, and I am looking for complete
instructions, including parts needed and sources for the parts. Can
anyone offer any help in this matter? Please e-mail <ko...@netsol.net>.

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[Michael Peters]

Ken Collier wrote:
>
> Does anyone have any experience modifying a Cobra 148 GTL CB radio for
> 10M ham use? I know it can be done, and I am looking for complete
> instructions, including parts needed and sources for the parts. Can
> anyone offer any help in this matter? Please e-mail <ko...@netsol.net>.

One idea may be to change the 11.3258 mhz xtal used to produce
the 34 mhz mixer fo. In the 142gtl the same xtal is 11.1125 mhz
and the divider input codes are shifted. If you would compare the
N codes and the mixer frequencies you may be able to figure out
what the frequency of the new xtal should be.

Michael
KB2UMJ

[William G. Nadzam]

All you need do is change the 11.3258 Mhz Mixer crystal to a higher freq.
For every 0.150 Mhz increase in freq of this Crystal you will get a
450Khz increase in operating freq.

Today this unit uses a MB8719 PLL. This PLL is running in the middle of
its operating range. Even with this crystal at 11.3258 Mhz the upper limit
of the operating area is 28.235Mhz and as low as 26.335 in 10 Khz steps.
To do this you would need to provide an external method of changing the control
lines to the PLL chip. Since the channel selector switch does not allow a
direct control over the PLL divider lines you can provide extrenal control
lines for the PLL that will allow you to get a larger range. Other factors
will get involved as well. Like the Last Xmitter mixer, and the VCO range,
but if you can live with a 450 Khz spread in the 10 meter band then just get
a crystal in the 11.5 ~ 12.0 Mhz range and retune the Mixer coil.

Ken Collier (ko...@netsol.net) wrote:
: Does anyone have any experience modifying a Cobra 148 GTL CB radio for
: 10M ham use? I know it can be done, and I am looking for complete
: instructions, including parts needed and sources for the parts. Can
: anyone offer any help in this matter? Please e-mail <ko...@netsol.net>.

: -------------------==== Posted via Deja News ====-----------------------

: http://www.dejanews.com/ Search, Read, Post to Usenet

--
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Name: Bill Nadzam "K8WN"
E-mail: Bill Nadzam <nad...@bills2way.com>
http://www.bills2way.com
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