radio dead key mod help

[unit_399]

The other 'option' is to put a 1k pot in temporarily long enough to set it at the desired dead key setting and then measure the resistance of that pot. Then use a switch and a fixed resistor (with the same/close resistance to you prior adjusted pot reading) to switch between your 1 watt dead key back to the standard 4 watt dead key.
That will work too . . .

The AM power pot in this radio (VR14) is 5K ohm.

 

[Robb]

The AM power pot in this radio (VR14) is 5K ohm.

Correct. But as sp5it pointed out in this thread, the best way to do this mod is at the pre-driver transistor. Which requires a 1k pot. I thought that is what we are talking about here - BTW. So Morse, I would review this thread and be clear about what you are doing before you do the work - of course!

 

[unit_399]

Correct. But as sp5it pointed out in this thread, the best way to do this mod is at the pre-driver transistor. Which requires a 1k pot. I thought that is what we are talking about here - BTW. So Morse, I would review this thread and be clear about what you are doing before you do the work - of course!

Robb-

You're right... I stand corrected... But, I don't understand why sp5it thinks it is better to adjust the final output at the preddriver stage. Now you have 2 adjustment points: the predriver and VR14. If adjusting at the predriver is better, why didn't the original circuit designer do it that way ???? I'm not saying sp5it is wrong, I just need him to explain why it is better to do it his way.

- 399

 

[Se7en]

Adjusting the pre driver to me is not something i would like to do.
i would rather run the 1k pot in series with VR14.... i have noticed, if i adjust VR14 max dk is 12w all the way down is do be determined ( as in my meter wont respond must be too low).
when running an external pot in series with VR14 will this mess with the pep at all? lets say for example im driving my amp at 2w = 90w and decide to go with 5w dk = 125w , my pep will still be max i assume no matter where the dk is set at?

 

[Robb]

Robb-

You're right... I stand corrected... But, I don't understand why sp5it thinks it is better to adjust the final output at the preddriver stage. Now you have 2 adjustment points: the predriver and VR14. If adjusting at the predriver is better, why didn't the original circuit designer do it that way ???? I'm not saying sp5it is wrong, I just need him to explain why it is better to do it his way.

- 399

You can set the variable at the pre-driver stage to zero resistance and then the VR 14 can be used to adjust the high dead key watts. I imagine there is less current at the pre-driver stage so it won't heat up the pot being used. That's a guess.

 

[unit_399]

Morse-

The easiest way to control the deadkey of your rig is to remove VR14 and replace it with a 5K ohm pot that you install whereever it is most convenient for you. People will recommend that you do a lot of circuit modifications that they claim is better, but going the easiest route is usually the best. Unfortunately, in this forum, people spend more time thinking about what they want to say next, and less about the question you are asking.. 73s

- 399

 

[Robb]

Morse-

The easiest way to control the deadkey of your rig is to remove VR14 and replace it with a 5K ohm pot that you install whereever it is most convenient for you. People will recommend that you do a lot of circuit modifications that they claim is better, but going the easiest route is usually the best. Unfortunately, in this forum, people spend more time thinking about what they want to say next, and less about the question you are asking.. 73s

- 399

lol Ya caught me!

 

[Se7en]

Morse-

The easiest way to control the deadkey of your rig is to remove VR14 and replace it with a 5K ohm pot that you install whereever it is most convenient for you. People will recommend that you do a lot of circuit modifications that they claim is better, but going the easiest route is usually the best. Unfortunately, in this forum, people spend more time thinking about what they want to say next, and less about the question you are asking.. 73s

- 399

thank you unit 399 well said and it answered what i asked.
one more question. when removing VR14 where does each leg on the pot solder to on the three spots on the mother board?

 

[Se7en]

VR14 removed pot put in place outside of radio. dk is now from almost 0w to 8w. used a 5k pot as mentioned. works good now i can hit the amp a little harder if needed