Hi list, 1) I bought a Hanna PWT, model HI 98308. As an electronics engineer, of course I had to take it apart to see the "guts". Very nice instrument! I am surprised they don't cost more.
A previous post by someone indicated his PWT could be calibrated with a precision resistor. for his model, 100K Ohm = 10 uS and 1 Meg = 1 uS. But with mine, 100K indicated 16.2uS. Obviously, there must be some difference in the electronics and/or electrode geometry between mine and his. Can someone tell me what value of calibration resistor the HI 98308 needs to read 10.0 uS? Or for a given reference resistance, what my PWT meter should read? 2) My distilled water reads 1.0 uS. Source is a neighbor's commercial steam distillation unit. Is that about as good as one could hope for without a lot of additional effort or expense? 3) When measuring CS with a PWT, how does one keep the electrode chamber from gradually getting silver in it which will affect the readings? Seems like the only easy way to clean it is to swish it around in some distilled water, or maybe use a water pik to squirt DW into the little electrode openings. Thanks, Steve Young
