After doing contract RF designs for 3 of the major avionics companies and two of the major land mobile radio manufactures for the past 31 years I can say that the comment about planned obsolescence is untrue and the real culprit is lack of support from the semiconductor manufacturers mainly because they have changed their business models away from supplying parts for a general broad range of RF market designers to a more select 5g and now 6 G cellular market where the majority of the money is at.
An example of just one RF area that has dried up:
Several years ago Texas Instruments acquired National semiconductor and several other smaller niche RF device manufacturers and withing a year TI obsoleted the entire national semiconductor line of what was known as the LMX line of Phase locked loop synthesizers which was used in thousands of frequency synthesizers in thousands of radios manufactured by big names such as Garmin, Bendix King, Wulfsberg Electronics, Technisonics Industries, Motorola, Harris, Ma/com Communications and numerous other transceiver manufacturers not just avionics and this resulted in these manufacturers scrambling to find replacement parts that Texas Instruments obsoleted during their buyouts without giving any advanced notice to us poor sucker RF designers tasked with keeping these old 20 year plus radios running.
Unfortunately after several years of purchasing replacement parts from what suppliers had a dwindling supply of OEM devices available, just several years ago the RF design market was hit with the second big change where even second and third source OEM replacement parts are no longer available and as a result the next choice made to keep the repair market running was to either redesign the product entirely or to design in what is called a daughter board where an entire no longer obtainable simple low density Integrated circuit is replaced with a circuit board made up of discrete components but this only applies to low density small no longer obtainable Integrated circuits and such.
Now we have hit the point in time where even if it were possible to re-engineering these daughter boards it is now no longer possible because even these discrete components used to make a daughter boards now no longer are being produced by the semiconductor house, IE even the replacement, replacement parts are no longer available.
Put the blame squarely on changing markets and where the big money is at people and this puts the blame squarely on 5g and soon to be 6G cell companies and satellite cellular industries because the discrete semiconductor parts manufacturers discovered that producing parts for small run niche markets such as avionics, ham radio equipment, public safety and fire radio manufacturers is no longer viable and the big money is now in 5G, 6G and soon to be satellite cellular markets.
The only recourse these days for us non cellular radio designers is to now move to an entirely new redesign methodology where we are now faced with using parts that are intended and marketed to the cellular equipment designers and as a result I myself am now stuck with not just designing new radios but also with having do the job that was once done by these same semiconductors manufacturers extracting data that was once readily provided for a wide RF market but is now only done for the cellular guys
As a result, even basic Rf design of non cellular products is of course not an easy Rf design task anymore and certainly it is no longer possible to keep these 15 year old or longer radio repairs running if their are no parts being produced by these merging semiconductor manufacturers.
Fortunately for me after 31 years I’m leaving the Rf design field in a year or two and I will no longer need to worry about second and third hand running in circles just trying to source parts that are not being produced anymore and have not been produced for 15 years or more but I really do feel sorry for the new engineer who replaces me and is tasked with spending 75% of her or his design career trying to source no longer produced components just to keep a piece of equipment alive for another 20 or 25 years.