Cobra 29 High Power mod with 2sc1969 transistor

[Chris Millas]

I installed an authentic 2sc1969 final in my 29 and left the stock driver. It produces about 20-23 watts.and has been running this way for years. I personally prefer the 1969 over any other final for a 29. It works well and sounds good if the radio is tuned correctly.

 

[Mr.715]

Ok back to another question that was raised here earlier maybe 3 pages back has anyone tried the new 2030+ or the hg1969+ I'm here there is one of those out now as well from hg.

I've been playing with the new HG2312s inside of the 29 chassis. Leaving all other components in the radio with the expection of changing a couple caps. C71 and the 1000uF south nearest audio transformer to a 3300uF (16-25v) after a tune with clean waveform we see it produce 28-34s peak depending on the radio. Each will slightly vary. Of course if it's a newer 29 chassis we need to remember to remove a turn off the coil of L14.

But I hope to repost a thread shortly after some further experimentation is done. And we have a complete guide for installation.

 

[Chris Millas]

I've been playing with the new HG2312s inside of the 29 chassis. Leaving all other components in the radio with the expection of changing a couple caps. C71 and the 1000uF south nearest audio transformer to a 3300uF (16-25v) after a tune with clean waveform we see it produce 28-34s peak depending on the radio. Each will slightly vary. Of course if it's a newer 29 chassis we need to remember to remove a turn off the coil of L14.

But I hope to repost a thread shortly after some further experimentation is done. And we have a complete guide for installation.

Mr.715,
Have you had a chance to do further testing with the HG 2312's in regard to the cobra 29?

 

[MKwrench]

Mr.715,
Have you had a chance to do further testing with the HG 2312's in regard to the cobra 29?

I used one (HG2312) in a pinch to repair a side mic. 29 LTD a while back, then monkeyed around with some trial and error stuff. It seems to make easy power the way it is. A clean 23pep without tweaks. These are from my notes some add a little more oomph, or help keep things sharp and clean:
It liked a 1957 driver with a 1ohm for R58, 330p or more (total) at C62, and a 22p across R55, the 22ohm bias resistor is fine. I used a 47uf at C71 (any smaller causes a bounce that I didn't like) changing C73 higher widens the voice frequencies that "pump up" the limiter, it needs experimented with if its needed, otherwise its fine as is. I have a 2.2 in one (very wide banded) radio. Beefed up the power filter caps at the inlet and audio chip/Transformer (C42 can help hold up the whole Radio). Keep the limiter (don't do the D11 or potentiometer mods), leave R48 alone too, but instead swap R67 (33ohm) for a 10ohm. The C67 and C38 changes are gold, but can cause a "bassy" voice output that doesn't sound good on some receivers, removing C69 seemed to add some highs to balance it out, but something should be there to keep TR18s "clicks" out of the mic line. Using 2SC1845 for TR17 is another thing to experiment with, for clear audio.
Lots of this stuff applies to more than the "high power mod". I just thought it would be cool to share for those of us who like to tinker and experiment with our radios.
To me the 2312 seems broader and the 1969 seems peakier, (if that makes sense).

 

[Harley3315]

I used one (HG2312) in a pinch to repair a side mic. 29 LTD a while back, then monkeyed around with some trial and error stuff. It seems to make easy power the way it is. A clean 23pep without tweaks. These are from my notes some add a little more oomph, or help keep things sharp and clean:
It liked a 1957 driver with a 1ohm for R58, 330p or more (total) at C62, and a 22p across R55, the 22ohm bias resistor is fine. I used a 47uf at C71 (any smaller causes a bounce that I didn't like) changing C73 higher widens the voice frequencies that "pump up" the limiter, it needs experimented with if its needed, otherwise its fine as is. I have a 2.2 in one (very wide banded) radio. Beefed up the power filter caps at the inlet and audio chip/Transformer (C42 can help hold up the whole Radio). Keep the limiter (don't do the D11 or potentiometer mods), leave R48 alone too, but instead swap R67 (33ohm) for a 10ohm. The C67 and C38 changes are gold, but can cause a "bassy" voice output that doesn't sound good on some receivers, removing C69 seemed to add some highs to balance it out, but something should be there to keep TR18s "clicks" out of the mic line. Using 2SC1845 for TR17 is another thing to experiment with, for clear audio.
Lots of this stuff applies to more than the "high power mod". I just thought it would be cool to share for those of us who like to tinker and experiment with our radios.
To me the 2312 seems broader and the 1969 seems peakier, (if that makes sense).

 

[Harley3315]

Seems to me it saw earlier nomadd mentioned using 2166 as the driver which means we could likely use the 2078 we swapped out for the fet. Now that said we would also want to swap in a larger predriver I've alread done this in the past. Although 1973 is hard to find now. Some of this is likely how drail gets crazy watts out of his radios. Ive also seen a mod where a relay is installed fed by the d11 traces is I remember right to provide voltage to the gate only on key up.