Over on the Antique Radio Forum, there's a conversation about VTVMs with a vacuum tube diode in the RF probe. Here's one of my favorites: the Sylvania Polymeter 302.
Sylvania Polymeter 302
There are a few more VTVM's with active RF probes in my collection.
General Radio 1806-A
Precision EV-20
Hewlett Packard HP 410B
Hewlett Packard HP 410C
(to do: complete this table)
Input capacitance
| Meter | RF probe input capacitance |
|---|---|
| Sylvania Polymeter 302 | 3.3 pF |