K5DH wrote:

Yes, you're right. Coils usually don't just come untuned.
However, other components in the circuit will change value
with age, often necessitating an alignment. This is even
more true with tube-type gear, where the heat takes a big
toll on components over the years.

So, I'm "Another Goldenscrewdriver tech", am I?

I am a professional electronic technician with 23 years'
experience with a major aerospace company, and an Extra
Class ham with 26 years in the hobby (a REAL Extra, not
a modern era "gimme" Extra). I've been building, fixing,
and restoring gear for all of those years. Because I'm
restoring a vintage CB radio rather than a piece of ham
gear, you assume that I know nothing and am just dorking
around with it? What are your qualifications? Are you
justified in making such observations about others?

Thanks for all of your insightful "help".

73,
Dean K5DH

In article ,
says...

Mots of the time coils just don't come untuned, why do you need to turm
them.
Another Goldenscrewdriver tech.




Dean -- I don't think it was meant that way, but it was a good
observation. I've am a retired Journeyman Technician, spent 26
years in the Navy all in electronics, was a Tech for Sony for 15,
years, a ham since 58 and have been building, repairing and whatnot
electronicswise most of my life -- and I should have thought to mention
that they seldom change as well. I've been caught in the 'Golden
Screwdriver' situation myself and just laughed it off.

Irv VE6BP
--
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Beating it with diet and exercise!
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58"/43"(!)/44" (already lower too!)
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Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Givem hell, Dean!



On the coils, I've found that heating the coil form (heat gun is best
but solder iron if done carefully ) will sometimes melt the wax on the
coil form allowing the slug to turn.

If not available, I have on occasion drilled a hole in the PC board
bottom of the coil; sometimes getting access for the tool through the
other end of the coil will make the difference.

If you do crack the coil, I assume you know its pretty much worthless
for reliability and proper tuning after that. Worse case, try to dig up
some used coils from other gear and just drill out the old core and
install a new one.

Good luck


Ed WB6SAT

"Ed G." wrote:

Givem hell, Dean!

On the coils, I've found that heating the coil form (heat gun is best
but solder iron if done carefully ) will sometimes melt the wax on the
coil form allowing the slug to turn.

If not available, I have on occasion drilled a hole in the PC board
bottom of the coil; sometimes getting access for the tool through the
other end of the coil will make the difference.

If you do crack the coil, I assume you know its pretty much worthless
for reliability and proper tuning after that. Worse case, try to dig up
some used coils from other gear and just drill out the old core and
install a new one.

Good luck

Ed WB6SAT

I have put an old Allen wrench into a stuck slug and heated it with a
large soldering iron, then carefully remove the slug by turning the
Allen wrench with a pair of pliers while the slug was warm enough to
melt the wax.

One other thing, some coils are sealed with "Printer's Ink", a water
based ink that chips easily. We used it on all the coils in the PRC-77
radios built by CE.

You have to be careful drilling holes in circuit boards. I have
worked on a lot of RF boards with traces run under coils that will be
destroyed with a drill bit.
--


Michael A. Terrell
Central Florida

I have put an old Allen wrench into a stuck slug and heated it
with a
large soldering iron, then carefully remove the slug by turning the
Allen wrench with a pair of pliers while the slug was warm enough to
melt the wax.


That's a good way of transferring the heat. But care must be taken
not to tork the allen wrench too much. I've broken far too many slugs
with those inflexible steel tools.


One other thing, some coils are sealed with "Printer's Ink", a
water
based ink that chips easily. We used it on all the coils in the
PRC-77 radios built by CE.

Thanks for that reminder. Forgot about some water soluble sealers.


You have to be careful drilling holes in circuit boards. I have
worked on a lot of RF boards with traces run under coils that will be
destroyed with a drill bit.

That's a given, that care must be taken where you drill. I've never
damaged a trace yet, though I've opted not to drill some. Of course if
the board has internal traces (sandwich) forget it!!


Ed

"Ed G." wrote:

I have put an old Allen wrench into a stuck slug and heated it
with a
large soldering iron, then carefully remove the slug by turning the
Allen wrench with a pair of pliers while the slug was warm enough to
melt the wax.


That's a good way of transferring the heat. But care must be taken
not to tork the allen wrench too much. I've broken far too many slugs
with those inflexible steel tools.

One other thing, some coils are sealed with "Printer's Ink", a
water
based ink that chips easily. We used it on all the coils in the
PRC-77 radios built by CE.

Thanks for that reminder. Forgot about some water soluble sealers.


You have to be careful drilling holes in circuit boards. I have
worked on a lot of RF boards with traces run under coils that will be
destroyed with a drill bit.

That's a given, that care must be taken where you drill. I've never
damaged a trace yet, though I've opted not to drill some. Of course if
the board has internal traces (sandwich) forget it!!

Ed

The last boards I worked on were 16 layer. About the only place you
could drill was through a bad via the connected the top and bottom
layers. At up to $8000 per board, they were rather fussy about extra
holes in new boards.
--


Michael A. Terrell
Central Florida