LND 723
JM: have assortment of bare tubes. Notably, my Ludlum 15 also has one as the alpha probe
"all end-window LND probes are known to violently vaporize themselves into oblivion if overvolted(including spikes)"
Contents
Specifications
- Recommended anode resistor (meg ohm): 1
- Maximum starting voltage (volts): 800
- Recommended operating voltage (volts): 900
- Operating voltage range (volts): 850
- Maximum plateau slope (%/100 volts): 10
- Minimum dead time (micro sec): 150
- Gamma sensitivity Co60 (cps/mr/hr): 40
- Tube capacitance (pf): 3
- Weight (grams): 150
- Maximum background shielded 50mm Pb + 3mm Al (cpm): 50
Socket
| # | Size | Function | Note |
|---|---|---|---|
| 1 | L | N/C | |
| 2 | S | V+ | 1M resistor to center |
| 3 | S | N/C | |
| 4 | L | Ground |
Units
| Case vendor | Case model | Tube vendor | Tube model | Works? | |
|---|---|---|---|---|---|
| XETEX | LND | 723 86-36 | No | Outgassed before I got it | |
| XETEX | LND | 723 86-36 | Yes? | looks okay but untested | |
| LND | 723 88-13 | No | M15 original tube. Outgassed during calibration | ||
| TGM | No | accidentally popped | |||
| TGM? | Yes | into M15? |
LND unit
Sample label:
LND, INC. 723 MADE IN USA 86-36
Ludlum 44-7 unit
From Ludlum M15 system
Original socket badly corroded. Repaired socket with cleaning + solder dip. However, ultimately the tube also had to be replaced
1M resistor in series on center + pin
Original tube degradation:
- Worked after cleaning
- Shipped to Ludlum for service
- Ludlum reported the tube wasn't reporting correctly
- Shipped back to me
- Tube unresponsive. Vacuum window noted no longer taught
XETEX unit
These have some sort of support electronics, leading to a 4 wire CMC connector instead of a typical coaxial connector
Sample data plate:
MADE IN USA SERIAL NO. 020969 XETEX, INC. Mountain View, CA
Other unit is S/N 020967
TGM unit
Looks identical to my 723 88-13, so assuming its LND
Data plate:
TGM DETECTORS INC. 34 Bear Hill Road WALTHAM, MA 02154 N210 S/N 3585
