Max carrier until the variable burns up?

[groundwire]

As far as these custom made amps go, what is the maximum carrier from the radio you can cut down with the variable on the amp before it burns up? My radio has a 5w carrier and i want to use the variable on the driver amp to set my level so the big amp is happy. Fyi, 5w is as low as my rig goes on am.

 

[Handy Andy]

Texas Stars (For example) use 100Ω ~ 250Ω 2W rheostats (carbon comp)

But use a resistor "pad" section to offer some means to lessen - at the same time parallel the resistors used to absorb that power from the radio ACROSS the input (fixed side) of that variable.

Then on that output TO THE INPUT ferrites - place a 68pF to 470pF (as a) shunt and offer a place to "tune" the input of the amps' SWR "condition" (Impedance)

You may have to do up a "hybrid" of Texas Star "Modulator V" and Killer Bee Dial-a-Watt (using parts from both to make your custom) for your custom.

 

[groundwire]

Im not building one. I just wanna find out if i can put 5w carrier into the 2x2879 hg driver and use the variable on it to turn it down without burning up the pot

 

[AudioShockwav]

It depends on how much the variable can handle and as Andy was posting about, if there is any padding added to bleed off input across it.

73
Jeff

 

[groundwire]

Ok gotcha. I dont know if it does or not, im not amp circuit savy. Thanks for the input guys, appreciate it

 

[Shadetree Mechanic]

What radio are you using? If you are getting the amp from a local shop, they might be able to turn the carrier down inside the radio so it goes lower.

 

[Handy Andy]

I realize that the thread may need a visual on the schematic side to show what I'm referring to...

The "blue wire" is the live RF arriving from the Relay - that the switch will bypass when the Dial-A-Watt is OFF - when pressed in (ON) the short is bypassed and allows the Variable Pot and R4 to work together in PARALLEL to reduce the amount of RF power that has to pass thru the variable.

Just put a resistor of a low enough value to get you thru your "range" across on the input to the Variable (R4) - you use another low-value resistor to attenuate the whole mess before it arrives to the variable - you may need a cap placed from the live line - across to ground somewhere between the attenuator resistor and the variable and R4 combo - to help with SWR balance.

 

[AudioShockwav]

I brought this thread back from the dead because it has useful info in it.

73
Jeff