Re: #uBiTx CW RF power out #ubitx

Jerry Gaffke


Pretty much all reports of blown TDA2822's have been with the "WX" branded clones,
they can blow catastrophically if fed 12v.  Even the WX parts seem to work fine
if the board is modded to add a voltage regulator so they only see 5 or 6 volts instead of 12 volts.

I have not heard of trouble with the FCI branded TDA2822's, even at voltages over 12v.
Though they will get hot if they are asked to deliver too much power to the load.

Do you have the volume turned way up?
Does your chip still get hot if your turn the volume control all the way down?
If the chip gets hot at moderate volumes, but is not hot when the volume control all the way down,
perhaps you simply have a defective speaker, try switching speakers.

Could be that there are ultrasonic tones coming from the receiver that the TDA2822
is dealing with that you can't hear, causing the chip to overheat.

Could be that there are ultrasonic oscillations at the TDA2822 for some reason,
though there have been no reports of that in the forum.

Those last two possible faults could best be seen with an oscilloscope,
though it wouldn't have to be a very good one. 
Here's one that's not very good
but should be adequate for looking at audio issues and is very cheap:
Better yet, ask around at a ham club, see if somebody with a scope
will look at it with you.

Jerry, KE7ER

On Fri, Apr 13, 2018 at 06:06 pm, Alan -MMØWXT wrote:
I have an FCI/FOI TDA in my ubitx batch 2. It is very hot indeed after rig on for an there an over voltage issue to the chip?

Join to automatically receive all group messages.