Thursday, 29 August 2013

[Amateur-repairs] Re: In search of the basic test equipment for workbench.

 

I agree that a tek scope should be your first purchase. I got mine from ebay and did some minor repairs. You can see a very basic workbench here: http://www.qrz.com/db/W8EZI

I have repaired a lot of transceivers and audio equipment at that bench. The radio sitting on the bench in the picture is a Icom 751A that belongs to a friend. It had burned out finals with associated damage.

Michael

--- In Amateur-repairs@yahoogroups.com, "k4tfj" <timothy.f.johnston@...> wrote:
>
> I haven't had a functioning workbench in 20+ years.
> But now, with an empty nest and rooms available, the bench will be born soon, but as with all newborns, it will be naked, with the exception of a couple DMM's and a MFJ-259B antenna analyzer.
>
> The DMM's are fairly basic, but one has frequency measurement to 10MHz and a capacitance function. The 259B has a frequency counter function as well as inductance, capacitance and the ability to generate un-modulated RF signals. I also have a DSI 5600A counter waiting to be repaired (just a bad 7805, I think). That being the current state of my test equipment.
>
> My intent is to be able to perform basic alignments and testing of my current radio gear, and a little experimentation and restorations. Rigs/radios include Conar 400/500, Kenwood TS-520s, Alinco DX-70T, assorted VHF mobiles and handhelds. Up for restoration currently is a Zenith 11S474 Receiver and a Hammurland SP-600-11 Receiver.
>
> Budget is $200-$300 a month, to locate and purchase affordable test equipment.
>
> My first instinctive thought is "I need an O'scope!!" and a VOM/VTVM capable of 3kvdc+.
> Any comments and recommendations on these?
>
> What other gear would you recommend and in what priority?
>
>
> TJ, K4TFJ
>

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Wednesday, 28 August 2013

Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 


I suppose one just needs to check with a scope to see what's coming out. The
ferroresonant Solas that I've seen produce clipped sine waves.

73

-Jim
NU0C

On Wed, 28 Aug 2013 19:35:50 -0700, Richard Knoppow wrote:

>
>----- Original Message -----
>From: "Jim Shorney" <jshorney@inebraska.com>
>To: <Amateur-repairs@yahoogroups.com>
>Sent: Wednesday, August 28, 2013 6:33 PM
>Subject: Re: [Amateur-repairs] In search of the basic test
>equipment for workbench.
>
>
>
>Solas don't produce a pure sine wave. This will tend to
>throw some voltage
>readings off.
>
>73
>
>-Jim
>NU0C
>
>
> Modern regulating transformers put out quite pure sine
>waves. Some very early Sola types did not. I doubt if the
>impurity would cause any significant measurement error
>especially after being turned to DC. The error in a meter
>depends on type of AC to DC converter it uses. A single
>diode, as found in RF meters, is RMS reading for very low
>levels, i.e. below about 1.5 volts, and becomes a peak
>reader at higher voltages. In the range where it is peak
>reading the error can be as large as the percentage of
>harmonics in the signal. Most audio meters and others like
>the Hewlett-Packard 400 series, use a full-wave bridge.
>These respond to the average of the waveform. The error from
>the RMS calibration can be several percent but is much
>smaller than for a peak reading meter. Of course, a
>true-RMS meter is immune to these errors. Note that both
>single diode and bridge type meters are calibrated in the
>RMS value of a sine wave which accounts for the error since
>they do not really read RMS.
> Non-electronic meters such as analogue VOM's are bridge
>type which respond to the average but are calibrated as RMS.
>
>
>--
>Richard Knoppow
>Los Angeles
>WB6KBL
>dickburk@ix.netcom.com
>
>
>

--
The universe we're in will reach absolute zero in three hours. Safe is relative. - Idris, "The Doctor's Wife"

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Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 


----- Original Message -----
From: "Jim Shorney" <jshorney@inebraska.com>
To: <Amateur-repairs@yahoogroups.com>
Sent: Wednesday, August 28, 2013 6:33 PM
Subject: Re: [Amateur-repairs] In search of the basic test
equipment for workbench.

Solas don't produce a pure sine wave. This will tend to
throw some voltage
readings off.

73

-Jim
NU0C

Modern regulating transformers put out quite pure sine
waves. Some very early Sola types did not. I doubt if the
impurity would cause any significant measurement error
especially after being turned to DC. The error in a meter
depends on type of AC to DC converter it uses. A single
diode, as found in RF meters, is RMS reading for very low
levels, i.e. below about 1.5 volts, and becomes a peak
reader at higher voltages. In the range where it is peak
reading the error can be as large as the percentage of
harmonics in the signal. Most audio meters and others like
the Hewlett-Packard 400 series, use a full-wave bridge.
These respond to the average of the waveform. The error from
the RMS calibration can be several percent but is much
smaller than for a peak reading meter. Of course, a
true-RMS meter is immune to these errors. Note that both
single diode and bridge type meters are calibrated in the
RMS value of a sine wave which accounts for the error since
they do not really read RMS.
Non-electronic meters such as analogue VOM's are bridge
type which respond to the average but are calibrated as RMS.

--
Richard Knoppow
Los Angeles
WB6KBL
dickburk@ix.netcom.com

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Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 


I like to have a decent shortwave receiver handy. My current preference is a
DX-400/CR-2021, but if you've got room for a R-390A ... Nice for sniffing
oscillators and IF stages, monitoring transmit signals, and it entertains you
when not serving as test gear.

73

-J9im

On Wed, 28 Aug 2013 14:16:48 -0700 (PDT), Jim wrote:

>Here's my list of essentials --
>
>-- Harbor Freight $2.99 DVM (OK to substitute a $299 Fluke 179 DVM) OK to have several
>-- MFJ-269 antenna analyzer (OK to substitute an MFJ-259)
>-- VTVM -- whatever's working, from the swapfest
>-- dual-channel 100 MHz analog 'scope, your choice
>-- AADE LC-2 cap/inductance meter
>-- RF power meter that's not subject to easy tampering, like a Bird 43
>-- el cheapo RF power meter like a CB tester, Realistic 3-meter is my preferred choice
>-- signal generator good to your max freq of interest, HP8640B recommended, with 1024 MHz option
>-- another signal generator, BA or GR is OK
>-- audio signal generator, HB is fine
>-- freq counter good to your max freq of interest, at least 6 digits, NOT some cheap piece of junk
>-- ESR tester, Chinese junk is OK
>-- big isolation transformer and big variac, minimum 5 amp
>-- homemade DC load capable of sinking at least 20 amps (a bunch of car headlights works FB) with a current meter
>-- RF dummy load, more than one, pwr good to your max HF output and another one good to your max freq
>-- probes and test leads as required for all the equipment
>-- coaxial interconnects as required for all equipment using coax connectors
>-- 30 or 40 dB coaxial tap good to at least 1 GHz
>-- big-a$$ DC power supplies at (nominal) 13.8VDC, 28VDC, 48VDC
>-- metered variable DC supply, 0 - 35VDC or thereabouts
>-- big-@$$ handful of clip leads, more than you can count
>
>One piece I've also found useful is one of Kent Britain's log-periodic microwave PCB antennas on a length of microwave-suitable coax, for use as a signal sniffer.
>
>And ... a shipping scale, so you can weigh your junk before you take it to the post office.
>
>
>Add to that, I have a couple of spectrum analyzers, but I don't consider those to be essential, just "nice to have."
>
>
>73
>Jim N6OTQ
>
>
>
>>________________________________
>>
>>
>>
>
>[Non-text portions of this message have been removed]
>
>

--
Ham Radio NU0C
Lincoln, Nebraska, U.S.S.A.
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!

"Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime."

HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
http://incolor.inetnebr.com/jshorney
http://www.nebraskaghosts.org

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Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 


Solas don't produce a pure sine wave. This will tend to throw some voltage
readings off.

73

-Jim
NU0C

On Wed, 28 Aug 2013 17:48:57 -0700 (GMT-07:00), Richard Knoppow wrote:

>-----Original Message-----
>>From: Bob Albert <bob91343@yahoo.com>
>>Sent: Aug 28, 2013 4:51 PM
>>To: "Amateur-repairs@yahoogroups.com" <Amateur-repairs@yahoogroups.com>
>>Subject: Re: [Amateur-repairs] In search of the basic test equipment for workbench.
>>
>>I don't think the Sola is a good idea for a test bench unless you have lousy line regulation. These days it's very stable. A 'variac' is a better choice, with voltmeter and, perhaps, ammeter.
>>
>>I have the Precision E200-C for sale.
>>
>>Let me know details of your VHF/UHF converters. My fastest 'scope goes to 275 MHz but my everyday 'scope only goes to 100 MHz.
>>
>>The signal tracer is kind of superfluous, if you have an oscilloscope.
>>
>>Just a few remarks after reading your list. Not a bad start at all, actually. An audio oscillator would be a nice addition.
>>
>>
>>Bob K6DDX
>>
> I agree about the metered Variac or even an unmetered one. The metered ones are rare and expensive. I bought mine before they became valuable. Its very useful because you can see immediately if there is a sudden rise in input current and shut the thing off. Its also fused.
> Unmetered Variacs are a lot cheaper and easier to come by. You can always rig it with a voltmeter and amp meter.
> Sola transformers work well but are mainly for regulation and filtering of the line. The Sola does have one virtue for trouble shooting, if the load is too high, like a short, it shuts down.
>
>
>

--
"There's something out of place – let's go and poke it with a stick." – The Doctor, "Amy's Choice"

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Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 



-----Original Message-----
>From: Bob Albert <bob91343@yahoo.com>
>Sent: Aug 28, 2013 4:51 PM
>To: "Amateur-repairs@yahoogroups.com" <Amateur-repairs@yahoogroups.com>
>Subject: Re: [Amateur-repairs] In search of the basic test equipment for workbench.
>
>I don't think the Sola is a good idea for a test bench unless you have lousy line regulation.  These days it's very stable.  A 'variac' is a better choice, with voltmeter and, perhaps, ammeter.
>
>I have the Precision E200-C for sale.
>
>Let me know details of your VHF/UHF converters.  My fastest 'scope goes to 275 MHz but my everyday 'scope only goes to 100 MHz.
>
>The signal tracer is kind of superfluous, if you have an oscilloscope.
>
>Just a few remarks after reading your list.  Not a bad start at all, actually.  An audio oscillator would be a nice addition.
>
>
>Bob K6DDX
>
I agree about the metered Variac or even an unmetered one. The metered ones are rare and expensive. I bought mine before they became valuable. Its very useful because you can see immediately if there is a sudden rise in input current and shut the thing off. Its also fused.
Unmetered Variacs are a lot cheaper and easier to come by. You can always rig it with a voltmeter and amp meter.
Sola transformers work well but are mainly for regulation and filtering of the line. The Sola does have one virtue for trouble shooting, if the load is too high, like a short, it shuts down.

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Re: [Amateur-repairs] In search of the basic test equipment for workbench.

 

I agree that a scope would be good to get next. You can find some reasonablely priced ones on Ebay that might just need a little repair or none at all. When I worked for a small company that repaired test equipment, all of us technicians outfitted our benches with test equipment purchased off of EBay. Most of the time with no repair needed.  You should be able to find a high voltage probe that will work with your vom and scope. A demodulator probe for the scope would come in handy too.
 
73,
John N4SME
 

>________________________________
> From: k4tfj <timothy.f.johnston@gmail.com>
>To: Amateur-repairs@yahoogroups.com
>Sent: Wednesday, August 28, 2013 12:01 PM
>Subject: [Amateur-repairs] In search of the basic test equipment for workbench.
>
>
> 
>
>I haven't had a functioning workbench in 20+ years.
>But now, with an empty nest and rooms available, the bench will be born soon, but as with all newborns, it will be naked, with the exception of a couple DMM's and a MFJ-259B antenna analyzer.
>
>The DMM's are fairly basic, but one has frequency measurement to 10MHz and a capacitance function. The 259B has a frequency counter function as well as inductance, capacitance and the ability to generate un-modulated RF signals. I also have a DSI 5600A counter waiting to be repaired (just a bad 7805, I think). That being the current state of my test equipment.
>
>My intent is to be able to perform basic alignments and testing of my current radio gear, and a little experimentation and restorations. Rigs/radios include Conar 400/500, Kenwood TS-520s, Alinco DX-70T, assorted VHF mobiles and handhelds. Up for restoration currently is a Zenith 11S474 Receiver and a Hammurland SP-600-11 Receiver.
>
>Budget is $200-$300 a month, to locate and purchase affordable test equipment.
>
>My first instinctive thought is "I need an O'scope!!" and a VOM/VTVM capable of 3kvdc+.
>Any comments and recommendations on these?
>
>What other gear would you recommend and in what priority?
>
>TJ, K4TFJ
>
>
>

[Non-text portions of this message have been removed]

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