"Do Litlle Jr." wrote:

"Michael A. Terrell" wrote in message

Not in transmitters and commercial radios.

True, however, if one compares an old Collins auto-mechanical
transmitter / receiver (the one with brass gears) from end WWII era,
with the latest designs than you have to admit that alignment / tuning
has also changed dramatically. Now with all crystal controlled PLL
frequency synthesizes, pre-tuned ceramic/crystal devices and cavity
resonators, the need for realignment / tuning has really been
minimized, specially in the IF sections.

A lot of old equipment is still in daily use, in some fields. I have
worked on transmitters up to 130 KW Visual and 65 KW aural. You don't
replace these every year or two.

I worked on the production line for an $80,000 (US) telemetry
receiver (RCB2000)and there were still a lot of adjustments to be made
even though it had a dual DSP front end, massive FIR filtering, digital
signal combining and 12 microprocessors. I had a set of ceramic
alignment tools that cost a couple hundred dollars issued by the test
department. The replacement tips were around $45 and would shatter if
dropped to the floor the wrong way.

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Michael A. Terrell
Central Florida