Note
73, Dec 1971, p. 16.
73, Aug 1972. p. 100.
73, Feb 1973, p. 124.
Provides 46 kHz of coverage in the Novice bands on 80 and 40 meters.
The ad does not explain how the device works, but "pulling" a crystal to a slightly different frequency is a common trick using a variable capacitor. This is how a "trimmer" works.
In its ad, the company published a letter from the FCC assuring that the NVX-1 complied with rules dictating crystal control for Novice class license holders.
Frequency coverage: 3702–3748 kHz, 7152–7198 kHz
The NVX-2, released in August 1972, was the same device but covered frequency ranges usable by General class (and higher) license, and permited the use of FT-243 crystals you might already have laying around.
Provides 50 kHz on any two frequency segments from 5–9 MHz "depending on the crystal."
Uses crystals that are half of the frequency desired output–4 MHz for 8 MHz output, for example.
Both units:
Output: 30 volts RMS
Requires 250–300 VDC, and 6.3 volds AC or DC.