Glad it was helpful. This forum was extremely helpful to me from the start, so I hoped I could pay that back somehow.
I just recently ordered the Kensington K38021US from Amazon.
The unit I got came with documentation whose type size is so small I had trouble reading it even with my glasses on. :-/ So I might have missed some info in it -- but I
think they omitted info about the initial charging time! It took less time than I thought to charge the Kensington to full capacity, but on the advice of their support line I left it on the charger a full four hours.
Do you know the best USB pass through for the Yeti 501 that will work with the Kensington? Where do you suggest I buy one from?
I've bought 510 passthroughs from two vendors: Electronicstix and Widows Bead Work. Prices were comparable, as I recall. Widows Bead Work includes shipping in all prices. The passthroughs from both places appear identical to me. Both vendors were very attentive in e-mail and quick to ship. The passthroughs I got from both places have manual activation buttons and both have an additional battery in an in-line battery box (you've probably seen those in the illustrations).
I've heard people say that you have to charge that additional battery before the passthrough can be used. Maybe the battery supplied with the ones I got already had some charge. I was able to start using the passthroughs right away (via powered USB hub rather than by connection to the computer). That in-line battery does work for power in a pinch when the passthrough is off the USB connection, though I don't know how long the charge holds.