Discussion:
time-nuts Digest, Vol 157, Issue 11
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Joseph Gwinn
2017-08-07 18:51:32 UTC
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Message: 2
Date: Sun, 6 Aug 2017 15:56:33 -0500
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt question
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Thanks everyone. This has given me a lot of things to check as I
further investigate over the next few evenings. I'll let you know
what I find.
Chris
On Aug 5, 2017, at 3:07 PM, Charles Steinmetz
I’d say it would be an MMIC amp similar to this device [Avago MGA-87563]
If a chip similar to the Avago part Arthur referenced is what is
installed, which seems plausible, the 0.749v on the RF input (Pin 3)
is a fault and is caused by an external source of voltage (3.417v)
imposed on the RF output (Pin 6) through the internal feedback
resistor to Pin 3, attenuated by the gate resistor.
Avago says this particular chip needs to have 0vDC at Pins 3 and 6,
so if the connected parts would impose any DC voltage on those pins,
external blocking capacitors must be used on Pins 3 and 6. You
might check to see if there are blocking caps (at least at Pin 6),
and if they are good. (Alternatively, the internal output capacitor
from Pin 6 back to the output FET source may be bad.)
Of course, don't expect a bad external cap to be the only other
problem -- if it is bad, the 6-pin amp may well be bad, as well as
whatever is connected to the other side of the cap.
Best regards,
Charles
<Avago_MGA-87563_equiv_circ.png>
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Message: 4
Date: Mon, 7 Aug 2017 10:57:10 -0400
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Machining some aluminum help!
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I don't want to start a flame war here but I tend to take the
recommendations in Machinery's Handbook as the basis for process
decisions.
for the last 75 years Machinery's Handbook recommend Kerosene as a
tapping fluid for Aluminum even for forming taps
I'm not finding this. I'm looking at the 27th edition (2004), and on
page 1147 they talk of tapping (by cutting) aluminum with various heavy
oils or greases, and not kerosene. On page 1939, on cold-forming of
threads, they say that one should use a good lubricating oil, versus a
cutting fluid.

Is there somewhere else I should look?
Btw if anyone here has a machinists tool box that odd rectangular
drawer is for your copy of Machinery's Handbook
http://new.industrialpress.com/machinery-s-handbook-30th-edition-toolbox.html
WD40 should not be used in any machining operation
WD-40 is largely kerosene, with a bit of oil. It is widely used for
machining aluminum, such a drilling with a hand drill, but not much as
a circulating cutting fluid.
it was initially created for the USAF to remove water (WATER
DISPLACER formula 40) from missile parts which had gotten wet and to
leave behind a dry lubricant to prevent corrosion and force out water
via capillary action
Thats why it works on seized fasteners the capillary action gets the
lube into the corrosion cells allowing fasteners to move
All true. WD-40 is also good for softening self-stick labels that have
become hard and brittle.

Joe Gwinn
Content by Scott
Typos by Siri
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Message: 2
Date: Sat, 29 Jul 2017 20:57:56 -0400
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Machining some aluminum help!
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Kerosine is a better tap lube for Aluminum as it is more persistent
and less flammable
NO. Kerosene is *not* a good lubricant for _forming_ taps.
Kerosene (WD-40) and alcohol are good lubricants for _cutting_.
For _forming_, one needs something very viscous, something that
lubricates at very high pressures, at the yield strength of the
material being formed.
Joe Gwinn
Content by Scott
Typos by Siri
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Message: 7
Date: Fri, 28 Jul 2017 14:11:09 -0700
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Machining some aluminum help!
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On Fri, 28 Jul 2017 12:46:30 -0700
After mounting the tap in the drill
press and putting a dab of Crisco on the tap I was able to tap each
hole to a depth of 7/16" as fast as I could turn the handwheel!
Cool!
I suggest you get some real cutting fluid. The threads will be
smoother.
I second that. What I use is a lubricant wax made by Lenox, the saw
maker. It's intended for metal-cutting band saws, but works just
splendid for form taps. There are many equivalents.
By the way, when drilling aluminum, use denatured alcohol as the
cutting fluid. This will prevent aluminum gumming up the cutting edge
of the drill.
And, as others have mentioned, one does not use the same size drill for
forming taps as for cutting taps. The diameter accuracy required can
only be achieved by using the correct number (versus fractional) drill
bit size. Do not use Chinese drill bits - steel not good enough. US,
Japan, Germany et al are OK.
Joe Gwinn
RGDS
GARY
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Message: 5
Date: Mon, 7 Aug 2017 11:35:34 -0400
Subject: Re: [time-nuts] Machining some aluminum help!
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For _forming_, one needs something very viscous, something that
lubricates at very high pressures, at the yield strength of the
material being formed.
I've had excellent results with STP oil treatment, by itself or with
added Tungsten disulfide. I frequently tap under power at 20-150 rpm,
using Tapmatic self-reversing tapping heads.
I've heard of the STP approach - it's all high-pressure lubricant, to
make a clanky old engine sound young long enough for the sale to go
through. I was once offered an old SAAB for sale by owner. The
giveaway was when I checked the oil with a dipstick - the oil dripping
off the dipstick, left a long trail in the wind, like a spider trailing
a silk line. I passed on this find offer.

Another traditional high-pressure lubricant is Castor Oil - used when
pressing steel things together.

Joe Gwinn
End of time-nuts Digest, Vol 157, Issue 11
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