[ARC5] OT: Hally Instability.

[Arden Allen]

> I'm not doubting anyone who says their Hallys were stable.
I do know in 40+ years of hamming, I've handled dozens
of them and never seen a single one from the "ham"
market line that didn't show mechanical instablilty
and "wibble-wobbles" above about 12 MC.
Is it possible this was some sort of aging-related
design flaw that a few were spared?
Has anyone ever done a through investigation
to find the root of it?  Coils mounted on a long
band switch that will transmit shocks like a
tuning fork always seemed a candidate to me.
Most likely there are multiple causes.

Dave, let's not mix apples with pineapples among all the fruits and nuts on 
the subject of "stability".  It's not like computers where it's logic and 
reason v/s insanity requiring institutionalization.  There are several kinds 
of stability we must consider.  One should really be referred to as 
temperature induced frequency drift.  Another is the old "amplifier that 
oscillates and oscillator that will only amplify" conundrum.  A third is the 
one I think you are referring to, mechanical or microphonic frequency and/or 
amplitude modulation.  Yet another one varying power supply and/or AGC 
voltage Miller capacitance frequency pulling.  And the last one I choose to 
put into the basket is the effects crud and corrosion.

Consumer grade ham radios, particularly the lesser models of the esteemed 
manufacturers of olde that we love so much, were built from parts that were 
originally designed to address the rapidly growing and highly competitive 
market for AM broadcast receivers.  Anything built to operate at higher 
frequencies suffered from the adaptations to those AM band radio parts. 
Full advantage was taken of the installed manufacturing capabilities instead 
of utilizing parts designed to address the performance requirements of 
higher frequency operation.  It was all strictly due to the economic demands 
of manufacturing for the consumer market.  We all know this having been 
inside the bowels of cost is no concern military radios designed to fulfill 
the needs of military operations.  But it seems I'm preaching to the choir 
so I'll leave it at that.

Charlie, in his sleep, is kicking at my feet and it tickles!  He's always 
available to help with my e-mailing.  =:-)

Arden Allen
KB6NAX

He who is cruel to animals becomes
hard also in his dealings with men.
We can judge the heart of a man by
his treatment of animals.
—Immanuel Kant