cobra 200 gtl slide range

[dt307]

might get one of theese in with an issue thats common

its a v2 that you cant get to the zeros but display says you can lol

looked at the schematic and seen hows it done

yes i could play with the voltages or install the missing d321

but the circuit looks to be ok and it should slide ok unless the crystal 10.240 is the limiting factor

any one sorted out one of these before ?? thanks

[cb4ever104]

I think they're cr@p . Sorry . Couldn't help myself .

What's the story with D321 . Why is it missing ?

[dt307]

its showing as nc not connected sammy

im sure i can get it going where its ment to just thought i ask before i did any leg work

2000.jpg

[dt307]

i know i can mod it to get it to slide to the zeros correctly its just bizarre the radio will sit with the coarse at 12 oclock and be on say 27.555.00 turn it left and the display will show 27.550.00 but the tx and rx will be on 27.553.00 or 27.558.00 when display shows 27.560 when the coarse is cranked to the right.

[cb4ever104]

To be honest I know nothing about them Chris . Does the counter get it's reference signal directly from the VCO ? I'll maybe download the schematic and have a look myself .

[dt307]

looks like to be cpu controlled cant see any kind of reference from the vco
i may be wrong but the 10.240 reference for the pll is whats getting pulled by the clarifier
there is feedback from the pll to the cpu it might just compare that and set the displayed frequency.
prob talking through my ass and no nothing about them either m8 or want to...just trying to help a guy out

[dt307]

no wonder no one wants to work on these radios

imo they are utter crap

she goes to a zero now no probs

[cb4ever104]

no wonder no one wants to work on these radios

imo they are utter crap

she goes to a zero now no probs

Told you !

So , what did you do to it anyway ?

[radio pete]

as a 10m Radio they are fine but once moded to 11m the display goes out of sink the the OSC it's a CPU isue

[dt307]

as a 10m Radio they are fine but once moded to 11m the display goes out of sink the the OSC it's a CPU isue

i was thinking to get the display to read better by messing with the feedback to the cpu but not gonna bother.

it was the 10.240 xtal that was the limiting factor
tryed one from a uniden and was worse
one from an old cybernet worked a treat and got the display to read correct on a zero but is 1kc off on a 5
the owner said he dont care what the frequency shows as long as it does a zero

[dt307]

update on this bit of tat...
installed a fake mosfet pppppfffffff smoke lol..moving along its mine now.
mosfet in and working damage repaired.
put the frequency back to standard no zeros
audio was raspy distorted and just crap....got a friend to try his exactly the same
looked into them the main pa bias 2sc2290 is set by a resistor and not a vr and its @0.6v this is too low and running in close to class c no wonder it sounds pants on ssb (got that chips frying sound when breathing)
after trolling through about 10 different pa designs for these transistors confirms the resistor value is too high.
added one more resistor in parallel just one i had here and got the voltage up to 0.73v.
result is night and day nice clear audio.
upgraded the power reg as the original was toast due to the mosfet.
just need to sort the frequency drift out as its like raft in the rapids