Protek 506 resistance measurement confusion

[W1BCC]

Protek 506 - used, but new to me.  Nice rubber case and leads.

My Fluke 175 says a 10k resistor is 10k.

Using same leads, the 506 says 11.8k.  Shorting = 1.8k

Applied a thorough squint to the manual.  No calibration or reset options noted.  Even swapped out the fuses,

What happened?

Thanks,

--Brad W1BCC

[retiredcaps]

I suggest checking the input protection starting with the MOVs and PTCs.  A good MOV should measure 0L ohm using Fluke 175.  A good PTC should measure between 500 ohm and 1500 ohm (an estimate on my part).  Both can be done in circuit.

[srb1954]

Protek 506 - used, but new to me.  Nice rubber case and leads.

My Fluke 175 says a 10k resistor is 10k.

Using same leads, the 506 says 11.8k.  Shorting = 1.8k

Applied a thorough squint to the manual.  No calibration or reset options noted.  Even swapped out the fuses,

What happened?

Thanks,

--Brad W1BCC

Does the meter give correct readings on the volts and current ranges?

Check the voltage drop across the meter when measuring current. Does it comply with the burden voltage specified for the meter?

Try a different set of test leads.

Check and clean the input jacks.

[W1BCC]

Yes, tried swapping leads.  Also a little DeoxIt. 

Appears to measures resistance accurately, just with an additional 1.7k.

Otherwise, it seems to function properly.

Thanks for all the suggestions,

--Brad  W1BCC