A "mousie tail" is only a preferred name when it's used as a counterpoise against a "rubber duckie" antenna ;-)
i could have said 'rat tail', which is the name (a powered unit) they are marketed under, but i don't like rats. mousie is cuter.
Back in the '60s and '70s, Lafayette Radio's larger CB handhelds such as the Dyna-Com series incorporated "Range Boost Technology". Their cabinets were made of metal, allowing capacitive coupling to the user's body which formed a counterpoise, which increased range. Or so they claimed.
If you want a mouse tail for your FT817, for instance 20 M it has to be 16 ft long, for 80 M it has to be 125 ft long
Have you tried to put an actual rubber duck on the BNC or SMA of your HT? It's about as useful as the "rubber duck" antenna that comes in the box with the radio. That's my story and I'm sticking to it!
I tried it ( the counterpoise ) recently and it does not help. A better antenna replacement for the duck however does work quite a bit better.
The rubber duck supplied for the 817 is made to be used as is with the radio adding a wire to a bigger radio such as the 817 with more metal is surely going make knowing the length needed difficult and may not make a difference using the mfj 1899 or single band versions they do require a counterpoise and is easy to work out length I use a diamond scrh77 with a sma to bnc adaptor on my 817 works much better than rubber duck but I’m sure it’s tuned for a regular sized ht?? People correct me on this statement?
i finally came to the same conclusion. so much for vhf/uhf. i HAVE been told, however, to use a counterpoise with radio-mounted portable hf antennas, and drag it behind you when in the field. that is in a pause mode- field day is coming and i'm working on that.