TDI questions: Battery and Frequency

[dr_maddog]

I use a big box TDI (circa 2009) that has had the noise reduction modifications completed on it (op amp replacement). I have a large collection of notes on the TDI but had a couple of questions that I haven't seen addressed.

Battery:

In an effort to gain a little more depth I am looking into increasing the battery voltage vs using the stock TDI LiON batteries. I am thinking to use RAVpower powerbank that has selectable voltage output (16V/19V/20V) - 23000maH (allegedly).

Any risk in doing so? As I understand it the TDI draws power directly from the source without voltage regulation. I think my biggest issue would be noise or ripple of the supply.

Another idea I had was to simply use a good brand of LiON drill batteries (DeWalt or Hitachi). I suspect those would have a cleaner output but I am not 100% sure if the protection circuit resides in each battery or back in the tool/drill itself.

Frequency:

Anybenefit to replacing the frequency pot with a multiturn pot? or Adding a fine turn pot?


Thanks!!

[Carl-NC]

Only the TX drive runs directly off the battery, regulators power other circuits. The original TDI had some parts that were rated around 16V as I recall, so I wouldn't go above the standard 14.4V. When I designed the TDI-SL I upgraded all the power parts to run higher than 20V, though I can't recall exactly how high.

The freq adjust pot is digitized by the micro's ADC and therefore is a digital adjustment. I think it has 64 settings. A multi-turn won't make it any better.

[Geo]

One time i supplied the TDI with 26V dor 15...20 minutes inside my lab.
What i saw...
1. Don't remember exactly but the current consumation was about 30% more
2. Many components came hot and
3. very small difference at depth (about one inch for a 25mm coin) at air test.


My conclusion was to keep it as it was by the factory...

[dr_maddog]

Thanks so much for the replies Carl and Geo. I appreciate the info. You both saved me a lot of time and potentially damaging my TDI.

I plan to stick with the stock batteries/voltage. That is also good to know about the frequency pot. Always assumed it was analog but that means the digital representation works well!