Dead Key on the Realistic TRC-458 wont go below 3.5 watts?

[mr_fx]

For some reason I just can't get the dead key on my TRC-458 to go down below 3.5 watts

I would like to see around 1/2 - 1.5 watts DK

this was a very easy mod on my Cobra 29's

ideas?

 

[Robb]

I think it is VR8; but I'm not sure.
Someone else may know.
Wait for the 'for sure' answer . . .

 

[mr_fx]

I think it is VR8; but I'm not sure.
Someone else may know.
Wait for the 'for sure' answer . . .

cranked all the way down on VR8 is around 3.5-4 watts :sad:

 

[9C1Driver]

Maybe the pot is bad. On any SSB radio AM dead key is a snap with a VR pot turn compared to trying to set it on a Cobra 25/29.

 

[unit_399]

]Maybe the pot is bad.[/B] On any SSB radio AM dead key is a snap with a VR pot turn compared to trying to set it on a Cobra 25/29.

I agree with 9C1 ... Sounds like VR8 is defective.

 

[mr_fx]

I was thinking that it was a bad VR8 too... changed it out still no dice...

I am going to adjust L37

 

[Robb]

The tuning cans/coils on any radio for the RF output stage are impedance matching. In other words, that is the wrong move. You might get the power down; but all you have accomplished is to throw the impedance/balance off.

The best way to lower the dead key is to put a VR in the pre-driver stage. I cannot recall exactly which v.resistor value is added at what point in that circuit is my problem ATM. "sp5it" - a forum member knows exactly thow it is done, as I cannot recall the exact procedure.

But adjusting the tuning coils for less output is surely the wrong way to do it . . .

 

[unit_399]

MR FX-

Is the mike gain pot (VR6) turned down all the way ?? Since the 458 doesn't have a front panel mike gain control, you have to turn VR6 down all the way when setting the dead key.

- 399

 

[mr_fx]

TRC-458 Variable RF output and Broadbanding mod's

 

[kc8adu]

could be a leaky am regulator.

 

[psycho]

Just to be on the lighter side FX, do you own any radios that work OK? :laugh:

 

[mr_fx]

Just to be on the lighter side FX, do you own any radios that work OK? :laugh:

lol, atm several... I just don;t talk about them as much... this TRC-458 is working great now... BTW :tongue:

 

[slprydk]

I have had that problem after upgrading the AM power regulator, you can change D26 (5v zener) to a 3v or 3.3v zener, you may even be able to get away with it a little lower. But dont just chop it out or jump it, its there for a reason.

Jim