first light: my SP168 actually works!

[Laserman532]

So is there a relatively painless way to measure the current going to this SP168 tube so I can determine how healthy it is? Ie, I want to know what it is drawing at say, 500mW output, 1 watt output, etc. I am unsure if my 3 phase converter can take it much above 2 watts or so without the generated leg drooping excessively (but maybe it would be ok since it is a switcher afterall).

Ideally, someone who knows a lot about this biophysics switcher can say, oh, just put a multimeter here and volts reading times x = tube current. (dreaming here).

I have a scanned, reduced size schematic that I can sort of make out represents some sort of power supply but other than that it is mostly too small to read anything. I think there should be some test points in the supply for monitoring current, or maybe there is a shunt in series with the tube I can measure across..

you can use a clamp on amp meter on the around the red wire of the anode and that measurment is quasi accurate. The correct way is to place a known shunt device in series with the anode wire and measure the voltage across it.

If you can measure 30 amps and keep it running at 30 amps, with the field control at maximum you should measure from one leg of the cathode to the anode 237 to 243 vdc.

[LesioQ]

Hey Skyko,
Don't play with it for too long or You may abandon Your idea of living on a boat soon
Piotr.K

[mixedgas]

watch the cathode amps on those inverter thingies, would not WANT to sag that cathode before you sell it :-)

or just tow it behind in the dingy. Steal one of the droping,submergable sealed pod lifeboats off a oil platform to protect the lasers, and tow it as the dingy. I always wanted to ride in one of those and their 70 foot fall off the platform.

AFAIK, the biophysic POS is light feedback only, no current mode.



Steve

[Skyko]

the one thing I have been able to read on the too small schematic is that the biophysics supply has a switch for light or current mode. I do think however that this is meant more for a service tech to use than the end user and I have no documentation on what it may do, so am avoiding trying it. I didn't realize switching power supplies could cause cathode sag, but no damage there yet since I have not taken things higher. Probably best to put the whole thing in the hands of an owner with a better supply anyway. At least I have knowledge that the tube is gas intact and not at high pressure (starts right up) so it was worth the effort to wire up the biophysics unit.

Do you realize the drag a dinghy causes on a sailboat? You never tow anything when you are blue water sailing, except maybe a sea anchor if conditions get horrible

[GooeyGus]

I think your PSU is fine, but Steve was talking about the phase converter causing the cathode voltage to sag (if it cant keep up)

[Xytrell]

But the PSU should supply the correct current if the voltage from the phase converter is 208V or more.

[mixedgas]

But the PSU should supply the correct current if the voltage from the phase converter is 208V or more.

Not unless you have a unlimited supply line, and in that case you already have 3P.

The first thing to go is the cathode tranny voltage regulation as you load your pole pig. My best friend has a ronk rotary converter , that we have used here, and a guy I buy parts from has the home made 3P motor with cap bank version. In both cases, with a amp clamp and a voltmeter across the cathode, cathode power falls off as you load the pole pig/building wiring. You want that cathode at 1130 'C , not 700-800 where it will sag.

Interestingly enough, the biophysic switcher should be rewireable for single phase, but the biophysic switcher is regarded as marginal in the industry.

For the record, we were running up to 4.7 watts in my garage, a model 5 would be fine as its designed for single phase, but a 168 is a strain on single, and we were running I90MRAs in my garage, resulting in a pole pig that had to be glowing inside. tubes that have 240V of drop @ 30 amps are pushing it in a basement.

Steve

[mixedgas]

Do you realize the drag a dinghy causes on a sailboat? You never tow anything when you are blue water sailing, except maybe a sea anchor if conditions get horrible [/quote]


my intent would be to get off shore, cruise well out of cell phone range, find a leeward cove, drop anchor, and stop some where and sit, with something 21, female, and blond on my lap! I understand off the pacific coast that may not be wise, well at least the anchored part! I do own a copy of Chapman's Piloting, Seamanship, and Small Boat... but since a blue eyed chick with great legs talked me out of the academy I haven't read it much. Pitty, I'd have loved haze grey and under way, even if meant being just a CPO.

May you have
Fair Winds and Following Seas, And Inmarsat Internet for PL!

Steve

[GooeyGus]

Interestingly enough, the biophysic switcher should be rewireable for single phase, but the biophysic switcher is regarded as marginal in the industry.

hey Steve,
Could you elaborate on this? Would it be better to run this laser on the biophysic power supply or with a 265 PSU? The 265 we are going to hook this laser to has not been confirmed to be working as of yet. It looks like it's in good shape and everything but is there anything we should be careful of while starting up this head on my 265 for the first time? Thanks!!

Jason

[Laserman532]

might I interject here. If you have run the head on the medical electronics and it worked you have nothing to loose by fireing up the 265. Here is what will or could happen, nothing happens (cathode glows but no start...diagnose electronic problem), it works fine (current control & magnet control functions) open many beers, or something blows up (one way to find out if the supply functions). open many beers.

The head or the tube can not be hurt because it is functional right now, the worst case scenario is that the PS blows up and it is electronics which can be repaired.

If the tube starts goes max current, no problem just turn it off
If the tube dosnt start, try replacing the 741 op amp on the current control card.


I would first hook laser head up to ps and measure to see if anything goes to ground, anode, cathode leads both sides of the magnet that is about all there is.

my guess is you will have to figure out the interlock ckt and if you can not see anything blown up in the ps it should fire right up.

You guys got my phone number, you can call me after you get her hooked up and water ready to go. Relax, it SHOULD be just fine