The wavemeter was used more or less from the very beginning of radio communications in the Royal Navy right through to the 1950's when crystals became the norm. Its job was to provide a means to accurately tune transmitters to the required operating frequency or to tune into an incoming signal so that it could be measured and thereafter, applied to a receiver.  It was really big business and the equipment used was as big as many of our transmitters and receivers today. Anorak certainly would be a fitting word to use for anybody enthusing about how an FSA or a quartz crystal works today to achieve the accuracies required by modern technology, but wavemeters were something else demanding real skills from the users, and of course, special training courses either ashore or in-situ. What follows is a contents list from OU6313 [OU means Official Use, a series of books coming between Confidential Books {CB's} and {BR's} meaning Books of Reference] the Handbook of Signalling Equipment [other than V/S] fitted in H.M. Ships and Naval Shore W/T Station in 1938 - just before the start of WW2. It follows the same pattern of every other book of the same period on the subject of Radio Communications. These are titles and not clickable boxes; it goes:-

Reports Suffix Letters to Transmitter Sets Transmitting Sets Receiving Outfits D/F Outfits Wavemeter Outfits
Aerial Outfits Aerial Exchange Outfits Battery Outfits A.C. Supply Outfits Wa/T Outfits Wavemeters and Oscillators

Wavemeters and Wavemeter Outifts are high on the list as major units, reflected in the following file WAVEMETERS ETC 1938.pdf
Now lets put some 'meat on the bone', and use as an example a ship we are all only too familiar with, HMS HOOD. Click here to see Hood's entry from OU6313 -  use the PDF zoom tool and the scroll-bars for a good view of the data  hood comms fit 1938.pdf.  The first column on the left shows the ships name, followed by 220 to denote she was a DC ships generating 220V and then the year of her start construction. Now look right to the eighth column, the one that starts EA.  This tells us that she had an aerial exchange outfit EA [more of that later]; from the above PDF file wavemeters etc, her wavemeter and oscillator set was pattern 1492B with a G7 [5 to 25 MHz] and a G8 [1.5 to 6 MHz], note, both obsolescent but not obsolete! Her wavemeter outfit was GB. Using outfit letters GB we can see that she has a G56 Wavemeter and a G33 Oscillator.

I will be mentioning all the wavemeters and oscillators fitted in the Fleet so many years ago but just in passing. Additionally, I thought I would give you a detailed understanding of the kit fitted in the Hood so at the end of the day, you will understand the manner in which she achieved frequency determination.

First to the Pattern 1492B and the G7 and G8 outfits. This first PDF shows you a picture of Pattern 1492B and has an explanation text within the file Wavemeter patt 1492B.pdf.  Next to the G7 and G8 outfits G7 AND G8.pdf.  Finally to G33 OSCILLATOR G33.pdf and G56 WAVEMETER G56.pdf

Other ships before, during and after WW2 would have had the same or similar fits, and all would have been doing what the dear old Hood did to set watch on the correct frequency.  Easy for us, but for them, they had to work at it.  Hood's callsign was GECV and I can imagine her tapping out a string of V's followed by that magnificent callsign then the ending sign AR.

These were the very last wavemeters in the Fleet THE LAST OF THE WAVEMETERS in the Fleet.pdf  plus this file showing the picture [and details] of the GN Wavemeter GN PICTURE.pdf

A wavemeter of 1906 vintage 1906 TYPE WAVEMETER.pdf