Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I don't have much money at all. I'm looking for something very basic and cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

You can get a cheap DVM for a couple of bucks at Harbor Freight.

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.

"Cydrome Leader" wrote in message
...
tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.





Good point. However you will pay an accuracy premium on the DC and Ohm
ranges. Most VTVMs will only give 3% FS vs 1% with even the cheap DVMs.

"tm" wrote in message
...

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old service
data gave alignment and measurement instuctions referencing a VTVM.

However, by the time you add in an RF probe (missing from most VTVM's you
see on eBay) on a good working VTVM, you could probably buy a decent working
100mHz 'scope instead.

Back in the day, a VTVM was way cheaper - most people had no hope of buying
a 100 meg 'scope.

MarkZ .

On Mar 22, 8:58*pm, "Mark Zacharias"
wrote:
"tm" wrote in message

...



wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old service
data gave alignment and measurement instuctions referencing a VTVM.

However, by the time you add in an RF probe (missing from most VTVM's you
see on eBay) on a good working VTVM, you could probably buy a decent working
100mHz 'scope instead.

Back in the day, a VTVM was way cheaper - most people had no hope of buying
a 100 meg 'scope.

MarkZ .

The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. Certainly
much higher than the old Simpson multimeters.

" wrote in message
...
On Mar 22, 8:58 pm, "Mark Zacharias"
wrote:
"tm" wrote in message

...



wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old
service
data gave alignment and measurement instuctions referencing a VTVM.

However, by the time you add in an RF probe (missing from most VTVM's you
see on eBay) on a good working VTVM, you could probably buy a decent
working
100mHz 'scope instead.

Back in the day, a VTVM was way cheaper - most people had no hope of
buying
a 100 meg 'scope.

MarkZ .

The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. Certainly
much higher than the old Simpson multimeters.

+++++++++++++++++++++++++++++++

Now, the 100 meg scope would be my choice for working on the old tube
radios.
Should be able to pick up a good analog 100 meg scope for (way)under $100.

A good Tek 475 will do 250 megs. Just set up a search on ebay and wait.

Regards,
tm

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap.

**See:

http://www.ebay.com.au/itm/Knight-Va...em19da20 e8cf

Wot a tool.


.... Phil

On 3/22/2013 3:28 PM, Cydrome Leader wrote:
tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.




I worked on tube type radios for many years and never needed
a VTVM. A normal multimeter worked just fine.

Bill

"Bill Gill" wrote in message
...
On 3/22/2013 3:28 PM, Cydrome Leader wrote:
tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.




I worked on tube type radios for many years and never needed
a VTVM. A normal multimeter worked just fine.


Same here. That plus a good scope (2465B). Meets 90% of the needs. A useful
tool that helps save time is a good ESR meter to do a fast check of the
filter caps.

On Fri, 22 Mar 2013, Mark Zacharias wrote:

"tm" wrote in message
...

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old service
data gave alignment and measurement instuctions referencing a VTVM.

That was mixed. One minute it would be a high impedance point, like the
agc bus in a receiver, and the schematic would warn about using a VTVM.
But in other cases, the schematic would indicate that the the measurements
were made with a Simpsons 260 VOM. The high impedance point needed the
high impedance meter, but the VOM points expected the load of the VOM, so
using a VTVM meant the readings would be high. I thought the schematics
with the VOM measrued voltages were because the serviceman was more likely
to have VOM, so might as well list what they'd see.

VTVM weren't so great at RF. Generally you needed an external RF
detector. Yes, the 410B has a wonderful RF probe, but that's ane
exception. The average VTVM had an "AC probe" but had the diode in the
case, so there was that long cable to it, not making it suitable for RF,
even if the diode was okay for it.

The same with DMMs, lousy for RF if for no other reason than the diode
isn't at the probe. One could build an RF probe, plug it into the DC jack
on the DMM, that used to happen a lot and it makes no difference whether
the meter is a VTVM, a DMM or a VOM (except for the loading of the last).

The problem with DMMs is that the readout is digital. Not good for
peaking or watching treands. Once upon a time, decades ago, one company
had a DMM with a small analog meter for peaking purposes, but that never
was a trend. Instead, the best we get is a bargraph on an LCD readout, but
the one I have is so slow that it's not useful for peaking.

One might as well dig out a decent size meter (or even a tuning meter off
an old stereo) add a jfet input op-amp, and build a relative DC meter for
peaking. Don't fuss about calibration, the DMM is for absolute voltage.
You don't even need an stepped attenuator with precision resistors, just a
few divider resistors or even a high value pot. Since it's all relative,
you just need something to ensure the input doesn't deflect the meter too
much. And then use it when you need to peak.

As for finding a VTVM, a couple of years ago I was walking along a street
I'd not been on for a long time, lots car traffic though less foot
traffic. I look down, there's a cardboard box on the sidewalk, and inside
is an RCA Voltohmyst VTVM. Seems intact, I've never gotten around to
plugging it in. That was all, no other neat stuff no other garbage, and
no obvious store where it might have come from.

It becomes all a more interesting story since I probably was the only one
walking along there who'd recognize what it was and bring it home. If I'd
not gone that way for some extraordinary reason, the meter would have gone
to the garbage dump.

Michael

tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?


The 1 Meg resistor in the probe for DC measurements in the RF
sections. It prevents detuning by isolating the cable capacitance from
the circuit you're testing.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

"Michael A. Terrell" wrote in message
m...

tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?


The 1 Meg resistor in the probe for DC measurements in the RF
sections. It prevents detuning by isolating the cable capacitance from
the circuit you're testing.


--


Yes, that is why I sometimes wrap a resistor on the tip of the probe to make
the measurement.
Of course with a scope probe, that's not a problem.

Still, there is much one can do with a Harbor freight $10 DMM.

I wonder, if you could only have one instrument, what would you choose? If
cost were the main consideration?

"Michael Black" wrote in message
news:alpine.LNX.2.02.1303240024000.10296@darkstar. example.org...
On Fri, 22 Mar 2013, Mark Zacharias wrote:

"tm" wrote in message
...

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I don't have much money at all. I'm looking for something very basic
and cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old
service data gave alignment and measurement instuctions referencing a
VTVM.

That was mixed. One minute it would be a high impedance point, like the
agc bus in a receiver, and the schematic would warn about using a VTVM.
But in other cases, the schematic would indicate that the the measurements
were made with a Simpsons 260 VOM. The high impedance point needed the
high impedance meter, but the VOM points expected the load of the VOM, so
using a VTVM meant the readings would be high. I thought the schematics
with the VOM measrued voltages were because the serviceman was more likely
to have VOM, so might as well list what they'd see.

VTVM weren't so great at RF. Generally you needed an external RF
detector. Yes, the 410B has a wonderful RF probe, but that's ane
exception. The average VTVM had an "AC probe" but had the diode in the
case, so there was that long cable to it, not making it suitable for RF,
even if the diode was okay for it.

The same with DMMs, lousy for RF if for no other reason than the diode
isn't at the probe. One could build an RF probe, plug it into the DC jack
on the DMM, that used to happen a lot and it makes no difference whether
the meter is a VTVM, a DMM or a VOM (except for the loading of the last).

The problem with DMMs is that the readout is digital. Not good for
peaking or watching treands. Once upon a time, decades ago, one company
had a DMM with a small analog meter for peaking purposes, but that never
was a trend. Instead, the best we get is a bargraph on an LCD readout, but
the one I have is so slow that it's not useful for peaking.

One might as well dig out a decent size meter (or even a tuning meter off
an old stereo) add a jfet input op-amp, and build a relative DC meter for
peaking. Don't fuss about calibration, the DMM is for absolute voltage.
You don't even need an stepped attenuator with precision resistors, just a
few divider resistors or even a high value pot. Since it's all relative,
you just need something to ensure the input doesn't deflect the meter too
much. And then use it when you need to peak.

As for finding a VTVM, a couple of years ago I was walking along a street
I'd not been on for a long time, lots car traffic though less foot
traffic. I look down, there's a cardboard box on the sidewalk, and inside
is an RCA Voltohmyst VTVM. Seems intact, I've never gotten around to
plugging it in. That was all, no other neat stuff no other garbage, and
no obvious store where it might have come from.

It becomes all a more interesting story since I probably was the only one
walking along there who'd recognize what it was and bring it home. If I'd
not gone that way for some extraordinary reason, the meter would have gone
to the garbage dump.

Michael


The voice of experience! Thanks!

Mark Z.

If you could only have one instrument, what would you choose?

Easy. One of those super-whammy digital LCD scopes that can measure just about
everything.


If cost were the main consideration?

A budget model of one of those.

William Sommerwerck wrote:

If you could only have one instrument, what would you choose?


Easy. One of those super-whammy digital LCD scopes that can measure just
about everything.


If cost were the main consideration?


A budget model of one of those.





Yeah

A Hantek DSO 8060

Jamie

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.

Would you explain please? Is the FET input impedance so much higher that it
loads less than even a high-quality DMM?

Thanks.

On 03/22/2013 09:43 PM, wrote:
snip
The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. Certainly
much higher than the old Simpson multimeters.

The "Simpson multimeters" were generally VOMs rather than VTVMs, no?)

On 3/24/2013 8:45 PM, cjt wrote:
On 03/22/2013 09:43 PM, wrote:
snip
The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. Certainly
much higher than the old Simpson multimeters.

The "Simpson multimeters" were generally VOMs rather than VTVMs, no?)

I think those were the most common. In my lab I have one Simpson VOM
and two Simpson VTVMs.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

Mike Cook wrote:

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.


Would you explain please? Is the FET input impedance so much higher that it
loads less than even a high-quality DMM?

Thanks.


My Fluke 289 will measure correctly with the 40k probe doing
AC or DC. So won't a couple of older flukes I have.

THe only problem with AC and a HV-probe is you need to keep
the frequency down, otherwise, the small amount of cap present
on the input of the meter is going to attenuate it some.

It's very possible cheap meters on AC mode may not behave correctly
with a HV-PROBE and show great losses in readings.

I also have a scope meter that works very well with the HV-probe.
I just need to remember to scale the input properly.

Jamie

On Mar 24, 9:27*pm, Phil Hobbs
wrote:
On 3/24/2013 8:45 PM, cjt wrote:

On 03/22/2013 09:43 PM, wrote:
snip
The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. *Certainly
much higher than the old Simpson multimeters.

The "Simpson multimeters" were generally VOMs rather than VTVMs, no?)

I think those were the most common. *In my lab I have one Simpson VOM
and two Simpson VTVMs.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot nethttp://electrooptical.net

But there is another factor here that no one has considered. The OP
may be used to working with an old tube type VTVM of the kind he no
longer has and would be very comfortable with a similar replacement. I
still have and use my RCA Senior Voltohmyst that I built in 1962. And
it still keeps good time. Lenny

tm wrote:

"Michael A. Terrell" wrote in message
m...

tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?


The 1 Meg resistor in the probe for DC measurements in the RF
sections. It prevents detuning by isolating the cable capacitance from
the circuit you're testing.


--


Yes, that is why I sometimes wrap a resistor on the tip of the probe to make
the measurement.
Of course with a scope probe, that's not a problem.

Still, there is much one can do with a Harbor freight $10 DMM.

I wonder, if you could only have one instrument, what would you choose? If
cost were the main consideration?


My first new piece of test equipment was a VTVM, because I was
working on equipment where a 10% change in voltage was the norm. All
the other equipment was given to me as junk, and some had missing
parts. I learned to repair scopes, capacitor bridges and signal
generators with a borrowed VTVM and a tube data book.


Later in my electronics career, I needed four 4.5 digit meters on my
bench because all voltages had to be within 1 mV in circuits powered
with +/- 12 or 15 volt supplies.

I currently have four Fluke 8050 meters, four of the cheap H.F.
meters, two Fluke 8000, the original Dick Smith ESR meter, a couple
Tektronix scopes. (453B, 324, three 130D waveform monitors and a 1720
vectorscope.) I also have a military scope made by Magnavox. I have odd
equipment like a Microdyne C band signal generator to repair & align the
old commercial grade C band equipment, and some microwave link test
equipment. I still have a couple VTVMs, a bunch of HP signal
generators, and three or four Precision E200 AM signal generators. I
have designed & built test fixtures for projects as well. I have two
Cushman service monitors, and a Calibrator. I have an old Polorad
Spectrum analyzer that works from 10 MHz to 400 GHz when used with
external mixers. There is no one instrument that can do everything. I
worked from DC to 12 GHz This is what is left of my personal shop, after
I ended up 100% disabled. There are dozens of other items I didn't
list. I learned 40 years ago that you need the right tools to make
money on a repair bench, so I was always looking out for used equipment
from my home workbenches. Most business without their own cal lab would
sell off older equipment that needed repaired dirt cheap, or just give
it away. Before Ebay, a lot of equipment was sold by the pallet at
auctions for almost nothing. I turned down 16 pallets of equipment at
one sale because I had no room for it. They went for $2 each, or $32.
The winner was ****ed, because he was going to run it up on me.

--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

tm wrote:

"Cydrome Leader" wrote in message
...
tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.





Good point. However you will pay an accuracy premium on the DC and Ohm
ranges. Most VTVMs will only give 3% FS vs 1% with even the cheap DVMs.

Cheapo meters seem to do DC stuff OK, and I've never dusted off the Leader
meter for stuff like that.

It's really nice for AC though. There's nothing quite like the dampened
needle movement for stuff like an audio signal. No number of constantly
jittering digits on a DMM can compete.

Mike Cook wrote:
the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.

Would you explain please? Is the FET input impedance so much higher that it
loads less than even a high-quality DMM?

yes.

I can't explain why this is but a call to HP and a check of the schematics
do show an AC input impedance of 1.7M (or something else bizarrely low)
for some AC ranges on a HP44301 bench meter.

There's also this problem of leaking voltage back out onto the test
probes:

http://www.home.agilent.com/owc_disc...essageID=99671

It's not to say the 34401 sucks- it's a really nice meter, but simply
being an expensive piece of test equipment from a trusted brand doesn't
always mean you get infinite accurracy with infinite input impedance and
an superconducing burden load for current ranges.

There's no way this is the only piece of test equipment with weird quirks
either.

you can run in circles over stuff like this if you just assume it's not
your test equipment.

I had an incident with a failed diode in Simpson AC panel meter once. How
often do meters half burn out giving you wacked out readings? Apparently
it happens.

Jamie t wrote:
Mike Cook wrote:

the input impedance on throw away (and even good bench) meters can be
really really low on some ranges, like AC.

I use a Leader FET input? meter for stuff like this. These replaced VTVMs
but retain the essentially zero load on the test circuit.

One use is for takings readings with the 40kV Fluke probe. You'll get
dangerously low readings with pretty much any digital meter on AC ranges.


Would you explain please? Is the FET input impedance so much higher that it
loads less than even a high-quality DMM?

Thanks.


My Fluke 289 will measure correctly with the 40k probe doing
AC or DC. So won't a couple of older flukes I have.

Those particular probes (I think Pomona had some too) require a fixed
input impedance on your meter, or the divider math falls apart. It seems
Fluke has no problem with this, although I've not yet tested the probe
with my latest Fluke meter. THere really isn't warning about this on those
probes, although it says so in the manual, but who has those laying
around?

for microwave ovens, when they were worth fixing, a yoke tested was easier
and more certain for HV measurements.

THe only problem with AC and a HV-probe is you need to keep
the frequency down, otherwise, the small amount of cap present
on the input of the meter is going to attenuate it some.

I have no way to test outside of 60Hz, but I am curious about how far they
drift off.

It's very possible cheap meters on AC mode may not behave correctly
with a HV-PROBE and show great losses in readings.

I also have a scope meter that works very well with the HV-probe.
I just need to remember to scale the input properly.

wrote:
On Mar 22, 8:58?pm, "Mark Zacharias"
wrote:
"tm" wrote in message

...



wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM. I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?

Because a VTVM can be much better at RF frequencies. Also, your old service
data gave alignment and measurement instuctions referencing a VTVM.

However, by the time you add in an RF probe (missing from most VTVM's you
see on eBay) on a good working VTVM, you could probably buy a decent working
100mHz 'scope instead.

Back in the day, a VTVM was way cheaper - most people had no hope of buying
a 100 meg 'scope.

MarkZ .

The little HF LCD display multimeters seem to have pretty high input
impedance, but I've never actually tried to measure it. Certainly
much higher than the old Simpson multimeters.

they still make those simpson meters. I want to know who buys them, and
what for.

tm wrote:

"Michael A. Terrell" wrote in message
m...

tm wrote:

wrote in message
...
Hi Folks,

I'm working on an old tube radio (Zenith) and could really use a VTVM.
I
don't have much money at all. I'm looking for something very basic and
cheap. I had an old Heathkit but the meter/dial broke.

Thanks,
Gabe Read
Providence, RI

And the reason it needs to be a VTVM and not a $25 Radio Shack digital
multimeter is?


The 1 Meg resistor in the probe for DC measurements in the RF
sections. It prevents detuning by isolating the cable capacitance from
the circuit you're testing.


--


Yes, that is why I sometimes wrap a resistor on the tip of the probe to make
the measurement.
Of course with a scope probe, that's not a problem.

Still, there is much one can do with a Harbor freight $10 DMM.

I wonder, if you could only have one instrument, what would you choose? If
cost were the main consideration?

I think any generation of handheld fluke meter would keep me happy for
general troubleshooting.

the cheapiest working meter I have is some pocket sized Wavetek DMM. It
works fine and has a surprisingly good, high contrast large LCD.

I still have some Radio Shack analog meters, but they have burned out
ranges which should be easy enough to fix.

They still make those Simpson meters. I want
to know who buys them, and what for.

They require no batteries (except for the ohmeter), and it's easy to follow
rising and falling readings.

Cydrome Leader wrote:

they still make those simpson meters. I want to know who buys them, and
what for.


Military & industrial customers who have millions of pounds of
equipment where all readings in the manuals were taken with Simpson
meters.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

Michael A. Terrell wrote:

Cydrome Leader wrote:

they still make those simpson meters. I want to know who buys them, and
what for.


Military & industrial customers who have millions of pounds of
equipment where all readings in the manuals were taken with Simpson
meters.

that's a good enough answer.

I saw a simpson meter on a shelf at Argonne national lab recently and at
first though, wow, that's old, but changed that thought to wow, pretty new
stuff there for a government run lab.

I can understand the desire for an analog meter. These days I swear there must be more parts in a TV to keep it from working than to make it work. Shutdown, why ? There could be bunch of reasons. They are too cheap to really build current detectors into them so they assume when a voltage source is out or low there is an overload on it. So the sumbitch shutsdowwn before your DMM can measure any voltages. A VTVM will at least show you the neelde moving. On my DMM sometimes it's hard to see the "mV" indicator, and I think it is a bit slow even as autorangers go. Also when you see that needle move really fast you know to get off that test poinr=t and change the range NOW. Not after a cheap microprocessor finally notices that it is burning in hell.

I also have some of those cheapo DVMs from Harbor freight. We got them for quite a bit less than ten bucks, in fact I think some of them were four bucks. Literally cheaper than the nine volt battery they use ! What's more you cna always get a free one. We had one that wouldn't zero so we called them and they send out a new one. They said don't bother sending the old one back lol. Wwell it was good for another battery anyway. However those little things are plenty good for almost any general servicing.

Now when you are aligning an IF strip, it's easy to see why the VTVM might be prefered. I now usually use a scope but then I don't align radio IFs anymore anyway. In fact I don't align any IFs.

Now to the OP, remember the OP ? I happen to have a non working Heathkit IM-28 (I think it's a 28) that doesn't work. The meter movement seems to be good, but the zero pot shaft is broken. I don't know if it will zero or not, but that's the circuit. The meter is fine. I'll sell it for twenty bucks. that''s actually giving it away, UPS wouldd probably be seven bucks, and of course I have to find a box and all that, package it up etc.

If I am not mistaken, my Father built that. I am not sure and I am also not much of a sentimentalist. I just don't like to see things go in the landfill.

Also, I have a neat thing for your PCs if you want. Someone mentioned audio ? This is a nice little analog looking meter that monitors the sound level in your PC. It is chiefly used for hardware ripping, using the PC as an audio recorder of to set the levels for online streaming like you can do on Paltalk.

I got it from an ex soundman for the Beatles. He didn't write it, a guy named Chapman wrote it.

https://dl.dropbox.com/u/29948706/VUMeter.exe