Losing power (maybe)

[fred ungewitter]

Over the last months, it seems that I have to slow the travel speed in order to get cuts at a power level higher than in the past. Of course, the first thought is mirrors and lens cleaning. They weren't dirty, but got a cleaning anyway.

I finally found my DooHickey and began to test.

Previously (not on Stargate SG-1), I had determined that 65 percent power was sufficient to stay under the predetermined 28 ma current limit for my real 60 watt tube.

I used the one-to-one method Russ provides, about 40 seconds or so of zapping the black lollipop. It makes for easier math, although I generated a spreadsheet to keep track of things.

In summary, the laser appears to fire as low as 10 percent, although the previous testing wouldn't go lower than 12. The current draw bounces around single digits to around 30 percent power, at which point the current is 3.5 ma. That's 30 percent "commanded" power, which the DooHickey reads as 23.8 watts. Thirty percent of 60 is 18, which would indicate that I'm getting more power than expected.

Traveling up the scale, at the previously limited 65 percent commanded power, drawing close to 28 ma, but not over, the laser now generates a DooHickey calculated power of 59.6 watts, effectively providing 100 percent of capacity. Unfortunately, at this 65 percent level, the meter reads only 13.5 ma

As I type this, I'm wondering if the power is being absorbed somewhere in the middle, but the 13.5 ma level on the meter is confusing.

My next step will be to confirm that I have a good alignment, although the output is consistent with a clean line on the laser.

I'm probably going to use the DooHickey in intermediate locations, to see if I'm losing power between mirrors that I shouldn't be losing.

If I find that's the case, I'll suspect the meter is inaccurate AND there's a problem in the middle.

Does any of this indicate a failing tube? Any other suggestions are welcomed with open arms and an open mind.

[Pete Cyr]

1. If you dohicky is measuring power equal of slightly greater than the power you programmed in the later - that normal
2. If you dohicky and programmed power match and the ma meter is reading WAY low as compared to what it was originally - I would say your ma meter is wacked -out of cal and or failing OR there could be a high resistance connection in the ma meter circuit

3. So if the dohicky and the programmed power match (or are very close) can you cut or burn old file and achieve the same results.

4. If you are using the dohicky correctly ...believe it

[fred ungewitter]

Your suggestions are sensible and appreciated.

My concern is that it is taking higher power level settings and slower speeds than that required months ago.

Based on your suggestion 2, perhaps I have a poorly working meter as well as a failing component causing loss of output power?

[Pete Cyr]

You may be correct.
More power and slower speed are good indicators.
Check your mirrors clean and verify your laser alignment

[fred ungewitter]

My alignment test was fruitful. I discovered that the locking nuts on two of my mirrors, #3 and #2 were loose. In the process of correcting this, I have a tighter alignment than ever achieved. As a result, my speed has doubled from the previously poor performance, but not quite as high as I recall.

I have a replacement ammeter arriving in the next day or two, which may also shed some light on the subject.

[Pete Cyr]

Do you have any OLD files you can run today to evaluate performance vice working from memory?
Sound like you may be making progress...