[Adam Stouffer]

I have a Western Electric KS-5727-L1 tester which is basically a
re-badged Hickok 536. The meter has 3 numbered scales, 0-3000, 0-6000,
and 0-15,000. When the chart says to use the english dial and a minimum
reading is say 2700 what scale should be used?

Now a side question, doing the calibration procedures all the voltages
appear normal and the dials are very close to spec. Why do certain tubes
read good but extremely off the scale? As in the needle is bouncing on
the right. Is there something in particular to look for?


Adam

[JP]

On Sun, 31 Aug 2008 10:31:23 +0200, François Yves Le Gal
wrote:

On Sat, 30 Aug 2008 17:47:29 GMT, Adam Stouffer
wrote:

I have a Western Electric KS-5727-L1 tester which is basically a
re-badged Hickok 536.

Itself a 533 with an added line voltage meter.

When the chart says to use the english dial and a minimum
reading is say 2700 what scale should be used?

The English scale is the Replace/Good scale. A reading above 2 700 on the
top 0 - 3 000 Gm scale means that the tube is at the top of the Good range,
a totally meaningless reading (except for eBay sellers of questionable
tubes).

Tubes should be measured at realistic voltages for emission *and*
transconductance : a pumped tube still shows nominal transconductance with
very little emission!

Now a side question, doing the calibration procedures all the voltages
appear normal and the dials are very close to spec. Why do certain tubes
read good but extremely off the scale? As in the needle is bouncing on
the right. Is there something in particular to look for?

The tester should be fully checked, preferably by a qualified techie. What
WE describes as a calibration is only a basic alignment procedure. A full
calibration requires the use of bogey (reference) tubes - but don't worry,
most Hickoks can't be properly calibrated: they are either precise for small
signal tubes or for power bottles, not both...

Send it to Kennedy for cal...

[BretLudwig]

AFAIK the WE Hickoks had an independent oscillator to test directly heated
tubes more accurately. As far as bogey tubes goes, I think the preferred
procedure today is to use a FET based calibration module.

All vintage tube testers should only be used with a precision AC source
if more than casual results are desired.

--
Message posted using http://www.talkaboutaudio.com/group/rec.audio.tubes/
More information at http://www.talkaboutaudio.com/faq.html

[Adam Stouffer]

JP wrote:

Send it to Kennedy for cal...

Sounds like the way to go. Going to put a few things on ebay first to
bring up my paypal account.


Adam

[Adam Stouffer]

BretLudwig wrote:
AFAIK the WE Hickoks had an independent oscillator to test directly heated
tubes more accurately. As far as bogey tubes goes, I think the preferred
procedure today is to use a FET based calibration module.

I saw that idea mentioned on a tube tester site but it was called a "gm
emulator". Nobody really has any info on how its made. A DN2540 FET and
probably a handful of parts? Hey why aren't I selling these?



All vintage tube testers should only be used with a precision AC source
if more than casual results are desired.

The tester in question has a line voltage meter and rheostat for
adjustments, plus the AC in my apt is usually 120 exactly.


Adam

[JP]

On Mon, 01 Sep 2008 15:31:07 GMT, Adam Stouffer
wrote:

gm
emulator
http://www.diyaudio.com/forums/showthread/t-95834.html

[[email protected]]

On Sep 1, 2:11 pm, François Yves Le Gal wrote:
On Mon, 01 Sep 2008 15:31:07 GMT, Adam Stouffer
wrote:

I saw that idea mentioned on a tube tester site but it was called a "gm
emulator".

Silicon can't replace bogey tubes when it comes to calibrating a tester for
current and emissions.

Quite wrong. The precision is much better. And, there are no more
bogey tubes left. Any tube older than 25 years or so has had SOME
gassing making them useless for metrology even if they work fine in
practical circuits.

There are tests that silicon can't easily emulate such as multiple
gain curve plots done on pentagrid converter/oscillators and pentodes
used with varying screen grid signals, which some radar circuits used.
Regular testers do not make these tests.

The Hickok transconductance tube tester is a simple concept that can
be easily duplicated by the hobbyist. What you are buying with a tube
tester is the multiple sockets, configurations and heater voltages
which take a lot of complication.