Cobra 19XS weak modulation

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Outback
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Joined: Tuesday 6th Mar 2007, 23:18
Location: Hampstead, N.B. Canada

Cobra 19XS weak modulation

Post by Outback »

Hi men........

First off i ain't a Rocket Scientist when it comes to radios but i've been in CB for 40 years, secondly there ain't no such thing as a CB shop left within 200 miles of where i live, so i need a little advise from you guys.....(probably a whole lot :)

Amongst a box of CB stuff i got the other day (from a nice little old lady) was a little Cobra 19XS with a DIN pin Diesel power mic..........

I cleaned the rig up and put it on the air, receives good, shows 4 watts power on my Radio Shack meter but even with the power mic the modulation is low, shows only 60% (i cleaned the mic contacts and put a new battery in it)

I looked over a number of websites with Cobra mods but mostly it is foreign to me.........

i did download the schematics and parts list

Can anyone suggest in simple terms what i have to cut or adjust to get the modulation up..........

Just wanted to add, aside from truckers who run Stateside (i live in Eastern Canada) there hasn't been a modern radio around these parts for years, in fact there are very few CB guys at all....frustrating when you have to go for a drive just to talk back home to your wife on mobile :)

I have a old Uniden Grant SSB around here but it decided not to key up, that was fun when the DX was running and i could do ground contacts in the evenings with some guys 50-60 miles away.........

So back to that Cobra, any ideas guys?

Thanks
regards;
Dave from Canada
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Outback
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Joined: Tuesday 6th Mar 2007, 23:18
Location: Hampstead, N.B. Canada

Post by Outback »

Rick;

Thank you very much for your PM...I replied to you.

Thanks for your offer of help but i understand....

All the best tomorrow mate!

So this Cobra modulation question is still up in the air

No pun intended...... :lol:
regards;
Dave from Canada
Romstar
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Joined: Thursday 22nd Mar 2007, 18:49
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Post by Romstar »

Outback,

I have the Cobra 19XS Service manual and schematic I would be happy to e-mail to you.

In the mean time, you should try and adjust RV201. This is a variable resistor coming off transformer T201.

The AMC defeat is C253. You should jumper this ONLY if necessary.

Let me know.
Romstar
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