Power Resistor Characterization

[mawyatt]

Need to characterize some power resistors for higher speed applications than the usual audio frequency range. The Dale RH-10 10 Watt chassis mount type power resistors are what we've selected, and have served us well in the past; stable, rugged and reliable.

Normally to characterize these we would use some quality Kelvin Clips with our DMMs or LCR meters, however we need to check the resistor behavior up to ~1MHz and some cases ~5MHz. The Kelvin Clips we have aren't specified above 100KHz, which leaves the usual approach with a custom fixture (calibration), and maybe even for VNA use.

Then remembered {don't laugh, this is getting harder and harder  } some time ago we purchased some B&K fixtures (TL89F1 and TL89K1*) for our bench LCR meters, one of which has additional "adapter inserts" for leaded components V & H orientation.

Turns out these adapter inserts (TL89F1) have just enough spacing to allow the Dale RH-10 Power resistors to be inserted as shown. This fixture can be "zero/short calibrated" with the standard metal short for the normal leaded fixture use if the short is flipped over and inserted with the curved end which provides an excellent "zero/short" over the full range of our IM3536 (8MHz).

Now what was heading to be a PITA turns out to be a simple easy, accurate and repeatable measurement

* The B&K TL89K1 is the Kelvin Clips for BNC use with LCR meters and is a rebrand of the Tonghui TH26011CS, the TL89F1 is a fixture for leaded components (adapters for Horizontal or Vertical lead insertion) for direct mount to the LCR meter and from unknown OEM.

Best,

[exmadscientist]

Nice 

As a tangent, around here we had some trouble with poor construction on those Dale aluminum housing chassis resistors. The cores were falling out  We could have tried to fix them up, either unit by unit or with Vishay Dale (who have obviously been tampering with the ancient, proven design....) but we did the lazy thing and bought another brand. TE HSC parts are really nice! Not that we needed MHz out of them....

[mawyatt]

That's sad to know that Vishay has messed up these Dale resistors. We never had issues with them in the past, now concerned for use in newer designs!!

Thanks for note

Best,