Cobra 200GTL DX tuning problem

[FatFreddy]

Hello everyone. I recently bought a Cobra 200GTL DX, I know all the stories but It was a good price and it is so shiney I couldn't resist. So far I love it, it pulls the stations in and I am getting good reports but I find it impossible to tune between the channels on side band. If I stay to the fives it is great, but if someone wants to QSY to a zero I can't get to them. Has anyone else had this problem, or any advice for me.

[Animal]

Whaaaaaaaaaaaat? You bought a Cobra 200??? It's like a 9v battery & your tongue - you know you shouldn't but you still have to go ahead & try it anyway!

There's a couple of ways of overcoming this problem - all of which involve a trip to the Rig Doctor unless you're handy with the circuit diagram & a soldering iron !!!

It's got something to do with needing more inductance in series with the varactor (or varicap) by adding a RF choke coil or increasing the constant dc source to the clarifier control by replacing the resistor with one of a lower value.

If you've also got that 'chirpy' or 'warble' sound on the SSB modulation then you may also have poor dc voltage regulation of the clarifier circuit.

Good luck!

[FatFreddy]

Thanks for the reply Animal. I went into this with my eyes open, but I hadn't heard about the zeros problem. Apart from that it is working great, I have had lots of good dx contacts this week, and with my Cobra M75 power mike local stations who know me have said the audio sounds good. Your explanations sounds plausible, but way beyond my abilities, remember I bought it because it is shiny

I am waiting for a reply from Cobra Worxshopz. Anyone else here who has or has had one?

[chazwozza]

Early 200s had the problem of only having a 3kc shift is why u cant get zero later on it was improved to 7kc so shifts all the way down

[FatFreddy]

Hi chazwozza, thanks for the reply. This is a revision 2 model, the clarifier swings about 6.2kc either way, so it should get there no problem. According to the frequency counter I can get there easily, but I get nowhere near.

Cheers...Jim