Nuvistor type 8058 + New tube tester


Ashton Brown <ashton@...>
 

-- for any purists amongst us, or for anyone with 500+ Tek scopes {er, Stan?}
at below noted site:
http://www.tubesontheweb.com/matic.htm

I had imagined.. such a thing, especially given the rarity / cost of a 570 -- which may not do so well on internal leakage and similar measurements [?] Still, I suppose one would want to verify the gadget with a 570 before trusting computer s/ware numbers � l� GIGO.

Still.. it uses Doze. Maybe a dejunked 98SE-lite with no other tasks --
could manage this, if it's rebooted at least daily.
(I can verify that, "98-lite", at http://www.litepc.com/ - can reliably perform for years, if not stressed by installs/deinstalls and the usual fluff that soon craps up the Registry. Indeed, behind a proper firewall: it's almost a real OS! if you never ask it to walk AND chew gum.)

Nice that someone is still Thinking...


Ashton

Ashley40@AOL.com wrote:

Hi,
Here is another possible source.....They still aint
cheep....: http://www.tubesontheweb.com/TU11.HTM

Ms Ashley Hall
W7DUZ
Cornelius, Oregon

========Original Message======== Subj: [TekScopes] Sylvania Nuvistor type 8058 Date: 11/30/2004 2:18:27 AM Pacific Standard Time From: vk4tzl@bigpond.net.au To: TekScopes@yahoogroups.com Sent from the Internet (Details)


Craig Sawyers <c.sawyers@...>
 

http://www.tubesontheweb.com/matic.htm
Ugh. That parasitic box of relays (211 of them, he boasts) is the worst
nightmare. The "deluxe" version boasts connectors between it and the tube
tester (as opposed to hard wiring) and a painted box! There is no way on
earth that this nasty unit would pass an electrical safety test (where for
instance is the double insulation necessary with the voltages used?), and
woe betide him when the first user zaps themselves.

A far better unit, that you plug into your scope to turn it into a curve
tracer is here http://www.hagtech.com/vacutrace.html . A real 570 on the
cheap, made by what would appear to be a fairly respectible company.

Craig


jim_beacon2000
 

I had considered building something like this, as an expansion of the card operated high speed valve tester idea - you plug in the tube, select the type from a database and hit return! then it comes back with the condition / set of curves.

The computer bit is relativly easy, and the power supplies aren't too difficult, but the electrode switching matrix would have to be built of relays, and the cost was prohibitive, so it has been consigned to the shelf, until I find a lot of suitable relays at a very low price.

Jim.

----- Original Message -----
From: Craig Sawyers
To: Tekscopes
Sent: Tuesday, November 30, 2004 11:39 AM
Subject: RE: [TekScopes] Nuvistor type 8058 + New tube tester


> http://www.tubesontheweb.com/matic.htm

Ugh. That parasitic box of relays (211 of them, he boasts) is the worst
nightmare. The "deluxe" version boasts connectors between it and the tube
tester (as opposed to hard wiring) and a painted box! There is no way on
earth that this nasty unit would pass an electrical safety test (where for
instance is the double insulation necessary with the voltages used?), and
woe betide him when the first user zaps themselves.

A far better unit, that you plug into your scope to turn it into a curve
tracer is here http://www.hagtech.com/vacutrace.html . A real 570 on the
cheap, made by what would appear to be a fairly respectible company.

Craig


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Craig Sawyers <c.sawyers@...>
 

The computer bit is relativly easy, and the power supplies aren't
too difficult, but the electrode switching matrix would have to
be built of relays, and the cost was prohibitive, so it has been
consigned to the shelf, until I find a lot of suitable relays at
a very low price.
There was a unit in the early '90s called the Sofia. This worked with a DOS
program and a serial port. The tube was wired with a patch board, very like
the 570, so no relay matrix was needed. It used switched mode supplies to
generate the DC, then DAC controlled FETs to carry out the sweep and grid
steps. It really was all-singing all-dancing - you could do pentode
characterisation in pentode, triode and ultralinear modes, do tube matching
etc etc. Anode voltage to 700V, current to 500mA IIRC. Tubes came from an
extensive database, and safe operating area for the sweep was automatically
defined from plate dissipation and maximum voltages and currents.

Unfortunately they only sold 80 of them in three years, and discontinued
manufacture. I tried to buy the design from them, but we failed to
negotiate a sensible price (they wanted a huge sum up-front), so there was
no business case. Plus it needed a Windoze interface in this day and age,
and many of the chips were going obsolete (like a particular codec that was
used), so there was also a significant redevelopment exercise with a long
time to market.

Craig


Albert LaFrance <lafrance@...>
 

----- Original Message -----
From: "Craig Sawyers" <c.sawyers@tech-enterprise.com>
To: "Tekscopes" <TekScopes@yahoogroups.com>
Sent: Tuesday, November 30, 2004 6:39 AM
Subject: RE: [TekScopes] Nuvistor type 8058 + New tube tester


http://www.tubesontheweb.com/matic.htm
Ugh. That parasitic box of relays (211 of them, he boasts) is the worst
nightmare. The "deluxe" version boasts connectors between it and the tube
tester (as opposed to hard wiring) and a painted box! There is no way on
earth that this nasty unit would pass an electrical safety test (where for
instance is the double insulation necessary with the voltages used?), and
woe betide him when the first user zaps themselves.
Well said. What a hideous design - especially the "basic" version! It's
not portable, it undoubtledly has safety deficiencies as you note, it's
incredibly ugly, and worst of all it requires mutilating a classic piece of
vintage test equipment.

Albert


stefan_trethan
 

On Tue, 30 Nov 2004 19:26:24 -0500, Albert LaFrance <lafrance@att.net> wrote:




http://www.tubesontheweb.com/matic.htm
Ugh. That parasitic box of relays (211 of them, he boasts) is the worst
nightmare. The "deluxe" version boasts connectors between it and the tube
tester (as opposed to hard wiring) and a painted box! There is no way on
earth that this nasty unit would pass an electrical safety test (where for
instance is the double insulation necessary with the voltages used?), and
woe betide him when the first user zaps themselves.
Well said. What a hideous design - especially the "basic" version! It's
not portable, it undoubtledly has safety deficiencies as you note, it's
incredibly ugly, and worst of all it requires mutilating a classic piece of
vintage test equipment.

Albert
I don't think you get double insulation with most lab gear - you could simply pull any
4mm plug and hurt yourself. Compared to some commercial gear of the tube-age this unit seems safe ;-).
It's not bad looking IMO, for a metal case. What do you want? embroidery?
I don't really understand you guys, first there is the talk about making a similar thing and when
someone has done it you complain about the looks of it. If it needs converting a old piece of kit -
better than the scrapyard i'd say.
not understanding the complaints at all....

ST


Craig Sawyers <c.sawyers@...>
 

I don't think you get double insulation with most lab gear
Nowadays you *have* to - electrical safety regulations absolutely require
it.

- you could
simply pull any
4mm plug and hurt yourself.
Again, not now. Any chassis connector that has more than 50V on it has to
be shrouded, and impossible to get easy finger access. The same with any
cable plug that engages with it.

Compared to some commercial gear of the
tube-age this unit seems safe ;-).
Agreed - but it *not* a piece of tube age gear. It is a new piece of
equipment grafted onto a piece of tube-age gear. In fact, if he is selling
the two pieces as a unit (which he offers to do), it is aguable that current
safety regulations apply to the *whole unit* including the modified tube
tester itself.

It's not bad looking IMO, for a metal case. What do you want? embroidery?
No - but it must be possible to do better than a galvanised steel bucket.
It is entirely possible to use a cheap utilitarian aluminium chassis from
Hammond, and then spray it with black crackle finish paint (used in classis
car restoration work), or even Tek blue.

I don't really understand you guys, first there is the talk about
making a
similar thing
And here's the point. This guy probably lashed the original one of these
together for his own use - hence the appearance. If you look at the rest of
his site, his main business is selling tubes, so this assertion hangs
together. Then he thought "hey - maybe this thing will sell!". So what you
are getting is a chewing gum and string garage special - not a item of
professionally engineered measurement equipment. That is compared with the
Vacutrace or now-defunct Sofia, both of which were designed by companies who
make their living from designing and selling professional electronic
equipment.

Of course many of us could design and make something similar, and we'd
probably be perfectly happy with a chewing-gum and string garage special
appearance for our own occasional use. But I wouldn't want to pay good
money to buy somone elses bodge job.

better than the scrapyard i'd say.
not understanding the complaints at all....
The days of tube testers going into the landfill are loooong gone. Have you
seen how much they sell for on eBay?

Craig


stefan_trethan
 

On Wed, 1 Dec 2004 08:31:46 -0000, Craig Sawyers <c.sawyers@tech-enterprise.com> wrote:

I don't think you get double insulation with most lab gear
Nowadays you *have* to - electrical safety regulations absolutely require
it.

Well, then the regulations are unrealistic.
You can't use the gear if you can't access the voltage.
OK, 4mm plugs have those plastic sleeves now (though i don't know many who use them).
But as soon as you look at the other end, of say test leads, you have blank tips which are
meant to touch blank parts of a _exposed_ circuit.
So you can still easily kill yourself if you like.

The day a EE is no longer in danger of electric shock will be the day when he can no longer repair anything - it will be the world of throw-away glued together gear.
Safety regulations are nice, but as EE you end up in situatios where you are not protected by them, and need to use your brains to keep safe.
A easy solution for the tube tester would be a insulating hose over the cable bundle, and grounding the
metal box (which it probably is). Should the sockets be a problem the solution would be a plastic
cover with a safety switch to cover the tubes when energized (note: many people would end up
cheating that safety switch 'cause they are to lazy to operate the cover).

ST


Craig Sawyers <c.sawyers@...>
 

Well, then the regulations are unrealistic.
You can't use the gear if you can't access the voltage.
OK, 4mm plugs have those plastic sleeves now (though i don't know
many who
use them).
But as soon as you look at the other end, of say test leads, you have
blank tips which are
meant to touch blank parts of a _exposed_ circuit.
So you can still easily kill yourself if you like.
I for one wouldn't like to poke around with an exposed tip at (say) 500V DC,
and find it difficult to imagine under what circumstances one would wish to.
My Datron and Fluke voltage calibrators go up to 1100V with 50mA - easily
enough to initiate a visit to the Pearly Gates. And if I am using that sort
of output, I connect it up hardwired, switch on the output, and have at
least one hand in my pocket. A tube tester is just about as lethal - say
500V with a totally brain zapping 500mA available.

I have worked with pulsed carbon dioxide lasers, which use (typically) a
100nF doorknob capacitor bank charged to 20kV - and that sort of voltage and
energy storage demands serious respect; one wrong move and you are in the
queue for fitting to a wooden box.

The day a EE is no longer in danger of electric shock will be the
day when
he can no longer repair anything - it will be the world of throw-away
glued together gear.
Well, take a look at modern test gear, or domestic products. Tamper proof
screws, snap together or glued up cases, board replacement servicing. And
in test gear shrouded sockets on the outputs or inputs. Even audio gear has
to have shrouded binding posts, since a power amplifier can easily generate
100V p-p (and as I know from experience, you can get a decent finger-tingle
from an audio amp output). Sound reinforcement amps can produce 250V p-p
(1kW into 8 ohms), which is quite uncomfortable and demands good connectors.
Preferred now are "Speakon" connectors - which are sort of low cost, high
current shrouded coax type. Note "shrouded".

Safety regulations are nice, but as EE you end up in situatios where you
are not protected by them, and need to use your brains to keep safe.
Absolutely. And when servicing something, that is doubly important. We
have all learnt the rules though uncomfortable experience here, and even
then the odd fright still happens. I think the safety regulations are there
to make products fool- or incaution- proof under normal use; but of course
nothing can be damned-idiot proof.

A easy solution for the tube tester would be a insulating hose over the
cable bundle
Yes - but there is no evidence of this in the pictures.

and grounding the
metal box (which it probably is).
And I will bet that it doesn't meet with regulations. A protective earth
connection has to be green/yellow, has to be able to take a full circuit
current without burning out in the event of a fault condition (13A in the
UK), be terminated with a crimped lug that meets pull-test specifications,
and be screwed to the chassis with the correct sequence of lockwashers, nuts
and locknuts (I'd have to look it up to remember which).

Should the sockets be a problem the
solution would be a plastic
cover with a safety switch to cover the tubes when energized (note: many
people would end up
cheating that safety switch 'cause they are to lazy to operate the cover).
You make my point: there is no evidence in the pictures of any awareness of
safety. No sheathed cable bundle, no cover over the tube sockets etc etc.
For an example of how to do this properly, take a look at the test fixtures
that go on the front of a 576 and 577 Tek curve tracer - including an
interlocked lid.

Craig


robin.birch@...
 

Hi,
This is a fine example of where putting the necessary thought in the
development process pays dividends. Electronic Engineers, well any
engineer in fact, who is involved in development, or sevicing/repair will
be exposed to dangerous voltages, circumstances, mechanisms and so on. If
the piece of kit is designed, from the start, to be worked on in a safe way
then it is a whole lot easier to do without killing yourself or blowing the
piece of equipment up.

We have a family of machines that we are trying to get brought up to
reasonable safety standards from the maintenance point of view and it is
proving to be very very complicated as they werent't originally designed
with any of this in mind.

The same applies to test gear. I have built many bits of one-off test gear
for my own use. They won't be to the safety regs but they won't be that
far away from them as I put the necessary thought in when I design it up
and I like risking my own life far less than risking others. It is also
driven by professional pride.

Taking the point that people will defeat safety devices when they find them
irksome (covers and so on). This just means that whoever designed the
thing in the first place didn't think how the kit would be used. Most of
the reasons for interlocks can be done away with with some thought.

I wouldn't buy a pice of home brew test gear that could be dangerous, and
valve testers fall slap bang into this category, unless I was happy that I
would be ripping it to bits and redoing it from scratch.

Cheers

Robin

Principal Engineer - Collections and Deliveries
UK Mails Engineering

Technology Centre, Wheatstone Road, Dorcan, SWINDON, SN5 5XX

Postline: 5404 3275, STD Phone: 01793 483275, Fax: 01793 494891, Mobex:
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Michael Bender <Michael.Bender@...>
 

Craig Sawyers wrote:
Well, then the regulations are unrealistic.
You can't use the gear if you can't access the voltage.
I for one wouldn't like to poke around with an exposed tip at (say) 500V DC,
and find it difficult to imagine under what circumstances one would wish to.
This is a very strange conversation for me. I learned electronics from my Grandfather back in the 60's and we routinely probed around in power-up TV sets and other gear. He always emphasized safety (one hand in pocket, no conductive path to ground through your feet, discharge caps after powering off, etc...) and he died of old age. I've known many HAMs that are very safety conscious and yet also measure equipment that is powered up using sensible safety precautions.

Well, take a look at modern test gear, or domestic products. Tamper proof
screws, snap together or glued up cases, board replacement servicing.
I think that is more due to lawyers and economics of manufacturing and servicing than because we have rows upon rows of dead technicians and engineers clogging our cemeteries.

A easy solution for the tube tester would be a insulating hose over the
cable bundle [...]
I don't know, a tube tester is a specialized piece of equipment that is meant to be used by trained operators who I would expect would have more safety sense than members of the general public.

An analogy - scalpels and anesthesia apparatus can both be deadly when used by untrained persons, but, like tube testers and high-voltage power supplies and other tools of *our* trade, we are ostensibly trained in the proper and safe operation of our tools.

This reminds me of the movement in the UK a decade or so ago to provide front and side crash pads and other safety gear on motorcycles so that the rider would be protected in the event of an accident - at some point there is so much safety gear that the whole point of engaging the activity is lost.

mike


Craig Sawyers <c.sawyers@...>
 

I don't know, a tube tester is a specialized piece of equipment that is
meant to be used by trained operators who I would expect would have more
safety sense than members of the general public.
You need to read back through the thead to see where this discussion came
from - a really nasty tube-tester add-on.

Craig


Michael Bender <Michael.Bender@...>
 

Craig Sawyers wrote:
I don't know, a tube tester is a specialized piece of equipment that is
meant to be used by trained operators who I would expect would have more
safety sense than members of the general public.
You need to read back through the thead to see where this discussion came
from - a really nasty tube-tester add-on.
I have been following the thread and had a look at the web site - grey metal homemade box and all! Sure, it doesn't look like something that you can buy from Tek or Agilent, but it looks a lot like the gear that I and many others have made over the years at home. This add-on is clearly not for the mass-market, so I'm not sure why everyone is making such a big fuss over it.

I still make coffee by pouring boiling water over coffee grounds :-).

mike

--
----------------------------------------------------------------------------
Michael Bender E-Mail: Michael.Bender@sun.com
Sun Microsystems, Inc. Tel: 831-401-9510
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Menlo Park, Ca. 94025
Mailstop: UMPK14-260 MD: VPN/IMAP

Never give up! Never surrender!

----------------------------------------------------------------------------


Craig Sawyers <c.sawyers@...>
 

Sure, it doesn't look like something that
you can buy
from Tek or Agilent, but it looks a lot like the gear that I and
many others
have made over the years at home. This add-on is clearly not for the
mass-market, so I'm not sure why everyone is making such a big
fuss over it.
That is exactly the point, though. We all make stuff for our own use that
looks a whole lot like that electric death bucket, and worse - but there is
a world of difference between that, and providing a piece of kit you
designed for sale and commercial gain. It matters not one jot the size of
the market - you legally can't sell a single unit that does not meet safety
standards. End of story, really.

Craig


Michael Bender <Michael.Bender@...>
 

Craig Sawyers wrote:
Sure, it doesn't look like something that
you can buy
from Tek or Agilent, but it looks a lot like the gear that I and
many others
have made over the years at home. This add-on is clearly not for the
mass-market, so I'm not sure why everyone is making such a big
fuss over it.
That is exactly the point, though. We all make stuff for our own use that
looks a whole lot like that electric death bucket, and worse - but there is
a world of difference between that, and providing a piece of kit you
designed for sale and commercial gain. It matters not one jot the size of
the market - you legally can't sell a single unit that does not meet safety
standards. End of story, really.
I think we're straying from the topic of Tek scopes, Craig, and I'm waiting for you to post some bit of electronics trivia in response to one of yours or my posts on the electronic death trap :-).

Anyway, to beat this dead horse a bit more (and apologizes to the list in advance) - is it really illegal to sell something that doesn't meet safety standards? I can understand that it might not be a good idea in the event that your device kills someone and you get taken to court, but I've seen people selling lots of electronic gizmos over the years that are clearly homemade and clearly don't have a UL/CSA/CE/TUV/etc... certification sticker on them.

mike

--
----------------------------------------------------------------------------
Michael Bender E-Mail: Michael.Bender@sun.com
Sun Microsystems, Inc. Tel: 831-401-9510
14 Network Circle Tel: x.31807
Menlo Park, Ca. 94025
Mailstop: UMPK14-260 MD: VPN/IMAP

Never give up! Never surrender!

----------------------------------------------------------------------------


Craig Sawyers <c.sawyers@...>
 

I'm waiting
for you to post some bit of electronics trivia in response to one
of yours
or my posts on the electronic death trap :-).
<Grin!>

============================================================================
=============================================
INSTRUCTION SHEET
TYPE 874-FBL BIAS INSERTION UNIT



Figure l. Type 874-FBL Bias Insertion Unit.

SPECIFICATIONS
Current Rating: 2.5 A.
Voltage Rating: 400 V.
VSWR: Typically, Less than 1.25 from 300 MHz to 5 GHz.
Insertion Loss: Typically, Less than 0.4 dB from 300 MHz to 3 GHz, Less than
0.8 dB from 3 GHz to 5 GHz.
Dimensions: 4 3/8 by 3 7/8 in (ll5, 99 mm).
Weight: 6 1/2 oz (185 g).
U.S. Patent No. 2,548,457.

DESCRIPTION
The Type 874-FBL Bias Insertion Unit is a dc bias and isolation unit used to
bias devices installed in coaxial-1ine systems. It is particularly useful tn
measuring the immittance of semiconductor devices with a slotted line It is
fitted with locking GR874 connectors at both rf ports and 3 /4 -inch spaced
binding posts of the GR938 type at the dc input. See Figure l.

PRINCIPLES OF OPERATION
In the schematic diagram, Figure 2 , the inductor L2 and the capacitor C3
are designed to introduce the minimum discontinuity in the 50-ohm system
between the coaxial connectors at each end. Capacitor C3 dc isolates the
biasing system from devices connected to coaxial terminals "A", usually
signal generators or attenuators. The low-pass filter, L1/Cl/C2 prevents the
radio-frequency signals present in the coaxial line from passing out the
bias terminals. This filter has a cutoff frequency of about 1 MHz.

APPLICATIONS
Figure 2. Schimatic diagram for Type 874-FBL.
C1 = 3900 pF
C2 = 3000 pF
C3 = 4700 pF
L1 = 4.7 uH
L2 = 0.3 uH

The principal application of the Type 874-FBL Bias Insertion Unit is in the
biasing of semiconductor devices, in particular , in impedance measurements
in the frequency range 300 MHz to 5 GHz. Other applications include
construction of diode- or transistor- amplifier circuits in the coaxial
configuration and low, and high-frequency combining circuits.

SEMICONDUCTOR IMMITTANCE MEASUREMENTS WITH SLOTTED LINE OR DIRECTIONAL
COUPLER
The Type 874-FBL is usually installed at the generator end of an
immittance-measuring instrument, so that the small but observable
discontinuities of the bias unit are not introduced in the "unknown"
circuit. A typical configuration for two-terminal unknowns is shown in
Figure 3. For transistor biasing, another Bias Insertion Unit is employed at
the transistor as shown in Figure 4.

Figure 3. Use of the Type 874-FBL for immittance measurements on a
two-terminal unknown.

The require termination is:
l. A Type 874-W50BL, if scattering coefficients (reflection and transmission
coefficients), normalized to 50 ohms, are being measured.
2. A Type 874-D20L sliding short circuit, if y or z parameters are being
measured. In this case, an ideal open or short circuit is-required at the
transistor terminals. Because the finite loss in the Type 874-FBL is
aggravated if a voltage maximum appears at the choke within the unit, it is
sometimes necessary to use a line-stretcher (Type 874-LK10L) between the
Bias Insertion Unit and the transistor jig. This ensures that the open
circuit is of sufficiently high impedance and that the short circuit is of
sufficiently low impedance. The Type 874-LK10L and the Type 874-D20L are
adjusted together to obtain the final terminating impedance at the required
reference plane, while at the same time obtaining the highest VSWR. The
transistor test jigs recommended are the Types 1607-P41, -42, -43, -44
Transistor Mounts. These mounts are accessories for the Type 1607 Transfer
Function and Immittance Bridge that permit its use in measurements of
transistor parameters at frequencies up to 1.5 GHz. They accept over 30
commonly used transistor packages. These, and the Type 1607-P40 termination
kit, permit transistor measurements up to about 5 GHz, when used with
instruments such as the Type 900-LB Precision Slotted Line. Specific
procedures are given in the instruction sheets furnished with the mounts.

Figure 4. Type 874-FBL units used in measurements with a transistor mount.


Figure 5. Use of the Type 874-FBL with 1602-B UHF Admittance Meter.

WITH THE TYPE 1602 UHF ADMITTANCE METER
The Type 1602 is operated with the DET and GEN connections interchanged. The
conductance and susceptance standards are dc blocked with General Radio Type
874-KL Coaxial Coupling Capacitor units. The Type 874-FBL is connected to
the terminals labeled GEN at the rear of the instrument, as shown in Figure
5, but is actually in the detector circuit.

WITH AMPLIFIER OR OSCILLATOR CIRCUITS.
Experimental coaxial circuits involving semiconductor elements may be made
up with other GR874 components, with the Type 874-FBL employed for applying
bias to the elements.* The bias system in this case does not interact
significantly with the rf circuits. A typical configuration is shown in
Figure 6.

Figure 6. Typical coaxial test set-up in GR874 components that utilizes the
Type 874-FBL for rf transistor measurements.
TUNERS: Type 874-D20L adjustable stub in a Type 874-TL Tee
MOUNT: Types 1607-P1O1, -P102, -P111, -P401, -P41, -P42, -P43, or -P44

COMBINER
When combining a high radio -frequency signal and, say, an audio signal,
some isolation can be achieved with the Type 874-FBL because of the 4700-pF
blocking capacitor. A typical connection is shown in Figure 7. The reactance
of the 4700-pF capacitor is about 3500 ohms at 10 kHz.

Figure 7. Connection of the Type 874-FBL to permit combination of audio and
rf signals.

The complete line of GR874 coaxial air line elements and patch cords permit
easy assembly of coaxial systems utilizing the Type 874-FBL.

*Gelnovatch, V. and Hambleton, G. E., "l Gc Transistor Amplifier Stage Using
Linvill Technique", Proceedings of the IEEE, Vol. 52, No. lO, October 1964,
p. 1262.


GENERAL RADIO COMPANY
WEST CQNCORD, MASSACHUSETTS 01781
BOSTON $B!& (B NEW YORK $B!& (B PHILADELPHIA $B!& (B WASHINGTON, D.C.
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ORLANDO $B!& (B CLEVELAND $B!& (B TORONTO $B!& (B MONTREAL
Form 0874-0131-A April,1966
Printed in USA


John Miles <jmiles@...>
 

What a hideous design - especially the "basic"
version! It's
not portable, it undoubtledly has safety deficiencies as you note, it's
incredibly ugly, and worst of all it requires mutilating a
classic piece
of
vintage test equipment.

That's a pretty neat hack, actually. He claims it does not permanently
damage the Cardmatic (which I seriously doubt lives up to contemporary UL or
CE safety standards even without a large metal box wired to it).

Personally, I'd be tempted to build a self-contained unit with its own bank
of sockets using high-voltage IGBTs or a similar technology to do the
switching, but for his purposes and those of his customers it sounds like he
has arrived at a good working solution.

Maybe someday Ralph Nader's successors will manage to bubble-wrap the world,
perhaps with help from some of the others in this thread. I hope I've
already electrocuted myself by then.

-- john KE5FX


Denton, Adam (Exchange)
 

--- In TekScopes@yahoogroups.com, "Craig Sawyers" <c.sawyers@t...>
wrote:
=============================================
INSTRUCTION SHEET
TYPE 874-FBL BIAS INSERTION UNIT
Lengthy non-sequitor replies like this I find really annoying, far
more so than "off topic" threads. Why not remain silent if you've
nothing to add?

JMHO.

Adam


Michael Bender <Michael.Bender@...>
 

I was going through some old e-mail and I found this thread
from the TekScopes group concerning the Frankenstein automatic
tube tester that someone had built and posted to EBay. The
part of this thread that is interesting to me are Craig's
statements concerning electrical safety. I believe that
you are from the UK, right Craig? I happened to pick up a
UK electronics mag at Fry's last month (EPE I think) and
in all the DIY projects in the magazine that have a mains
power supply, there are lots of dire warnings about not
building the mains supply unless you know what you are
doing, earthing everything in sight, etc... almost to the
point of paranoia - kind of like the Aunt in "A Series
Of Unfortunate Events" :-). I don't see this in US publications,
and I'm wondering if this obsessions with electrical
safety is some sort of UK thing?

For example, from this thread:

Craig Sawyers wrote:
I don't think you get double insulation with most lab gear [...]
Nowadays you *have* to - electrical safety regulations absolutely
require it.

Compared to some commercial gear of the tube-age this unit
seems safe ;-).
Agreed - but it *not* a piece of tube age gear. It is a new piece of
equipment grafted onto a piece of tube-age gear. In fact, if he is selling
the two pieces as a unit (which he offers to do), it is aguable that current
safety regulations apply to the *whole unit* including the modified tube
tester itself.
I'm not saying that there is anything wrong with electrical
safety - I completely agree that if you don't know what you're
doing you probably don't want to be building even simple mains
supplies or poking around inside old Tek scopes, but I'm
interested in the cultural reasons behind what seems like an
overly obsessive approach to electrical safety in the UK?

mike


Craig Sawyers <c.sawyers@...>
 

I believe that
you are from the UK, right Craig? I happened to pick up a
UK electronics mag at Fry's last month (EPE I think) and
in all the DIY projects in the magazine that have a mains
power supply, there are lots of dire warnings about not
building the mains supply unless you know what you are
doing, earthing everything in sight, etc... almost to the
point of paranoia - kind of like the Aunt in "A Series
Of Unfortunate Events" :-). I don't see this in US publications,
and I'm wondering if this obsessions with electrical
safety is some sort of UK thing?
Well, it certainly isn't just a UK thing. For example have a look at
http://www.eh.doe.gov/techstds/standard/hdbk1092/hdbk1092.pdf

The key electrical safety approval body in the US however is UL
(Underwriters Laboratory) http://www.ul.com/ , to whom electrical equipment
has to be submitted for testing to determine whether it meets regulatory
requirements (although I seem to believe that there are UL approved test
labs elsewhere in the US). The problem with UL is that a copy of each
standard costs $450! So it is expensive to find out.

The requirements of UL are just as tough as the requirements in the UK and
elsewhere (I have had to have gear go through UL approvals in the past).
The difficulty that manufacturers of electronic equipment for sale
internationally have is that they have to simultaneously meet approval in
many territories - and the standards, although similar, are most certainly
not identical.

Regarding home-brew magazines, I am a little surprised that US mags seems to
be less diligent about warnings than similar UK ones - particularly given
the litigious nature of the US.

Craig