DONATIONS OF INFORMATION, ESPECIALLY PDFs OF MANUALS WOULD BE GREATLY APPRECIATED.
Helper Instruments Company, of Indian Harbor Beach FL, went out of business around
1999 and the remains were acquired by Zetron. Zetron elected to continue some of the
Helper line of audio test equipment, but not the RF testers, such as the SM-512, SM-520
and SM-1000 Service Monitors. Zetron, in turn, was acquired by JVC / Kenwood.
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Sinad Alignment
For Optimum Performance 354 kB PDF
This is the writeup that got Helper started - it's a quite readable explanation
of the the theory behind SINAD measurement.
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Helper Instruments Catalog
1.43 MB PDF
I believe this is the last catalog that Helper released while Bill was alive.
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Helper Instruments Final Catalog 9.53MB PDF file
Donated by Dennis Casey KØGWK
This one details the era when Susan, Bill's daughter took over the company after Bill passed away.
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Helper Instruments Desktop
Reference 322 kB PDF file Donated by Eric WB6FLY
A collection of charts, tone lists, SINAD test procedures, "and an
occasional discrete mention of the time saving, money making test
instruments by Helper Instrument Company." We think this is older than
the file below although it has the same information in it.
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Helper Instruments Desktop
Reference 439 kB PDF file Donated by John K3KR
A collection of charts, tone lists, SINAD test procedures, "and an
occasional discrete mention of the time saving, money making test
instruments by Helper Instrument Company." We think this is newer than
the file above although it has the same information in it.
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Sinadder model S-101 508 kB PDF
file
Photo 1
Photo 2
This is the manual for the original small sloping-front "Sinadder" unit from
the late 1970s, complete with parts layouts and schematics. After they came
out with the Sinadder II this became known as the "Sinadder I". Despite the
age, it's still a very useful test bench instrument.
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Sinadder model S-101 305 kB PDF
file
This is another manual for the original small sloping-front "Sinadder" unit,
with the 1992 schematic revision and a 1999 parts list.
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Sinadder 3
Front Photo 1
Front Photo 2
457 kB PDF file Donated by Eric Lemmon WB6FLY
This is the manual for the later flat-front Sinadder model 3.
Also see the Sinadder 5 Ground Lift Modification below.
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Sinadder Linear 5 (model SL-105) with optional
CML-1 addendum 1.4 MB PDF
An improved version with split pages 1.9 MB PDF
The SL-105 was available both with and without the CML-1 option (used
in cellular applications). There were later units that had a different
front panel (see this photo).
It is complete with parts layouts and schematics for the plain unit.
This PDF file does not have the schematic for CML option.
Here's a photo of the front of
a CML-1 Sinadder provided by Gary KJ4RED.
Here's a photo of the rear of
a CML-1 Sinadder provided by Gary KJ4RED.
Note that SL-105s were initially built in the SL-101 case, and
mid-production switched to the case shown.
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Sinadder Linear 5 (model SL-105) 1.6 MB PDF
donated by Paul N2XZF
This copy has a bit less gray background than the one above. No mention of option CML-1
is present in this manual.
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Sinadder Linear 5 (model SL-105) Ground
Lift Modification 310 kB PDF by Paul N2XZF
This simple mod, which also applies to the Sinadder 3, removes the earth ground on the test
input leads, which could destroy some audio output amplifiers that can't be grounded (such
as the Motorola GM300, Spectra, etc.).
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Lineman model LM-106 416 kB PDF
file This unit is used to test the AC and DC characteristics of the
leased phone lines used to control remotely located base stations. It is
also a very useful bench test instrument.
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Modulation Monitor model MM901 476
kB PDF file Donated by John K3KR
This unit works with an FM receiver. It gets its input signal from the 400,
450, or 455 kHz IF circuit.
ICs: U1 = MC3357P; U2, U3, U7, and U8 = LM348N; U4 and U5 = CA3130E; U6 = LM741CN.
Service Note: "If readings appear low, check and replace C24 and C25."
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Audio Frequency Counter model Toner-II 769
kB PDF file Donated by John K3KR
This unit displays frequencies from 50 Hz to 9,999 Hz. ICs: U1 = LM348N;
U2, U3 = CA3130E; U4 = MC14046B; U5 = CD4518BE; U6 = SCL4077A/BE;
U7 = ICM7207AIPD; U8 = ICM7224IPL; LCD DISPLAY = PURDY/AND # FE0202-C.
Service Note: "If the unit has difficulty locking onto CTCSS tones (but higher
tones are OK), check and replace C1."
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Millivoltmeter model RF-801 506
kB PDF Both this file and the one below donated by Mike Felack WA3WOM
Photos: Front panel
Rear panel
Helper Instruments RF-801 Millivoltmeter
hi-res Schematic 196 kB PDF This is the component layout and schematic
only.
Darrel WA7OIB found a probe schematic and created a
parts list. Here's an inside photo of the probe. It's
similar to the one used on Boonton RF millivoltmeters. He also built his own RF-801 meter;
click here for an inside photo.
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Matchbox model MB-500 990 kB PDF
Both this file and the inside photo below were donated by Don Mosher WB5BRY
Photos: Front panel
Inside
Rear panel
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Helper Instruments
SM1000 Operator Manual 12.44MB PDF file Donated by Dennis Casey KØGWK
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This page initially created 22-November-2012 by splitting all of the Helper
equipment from the Test Equipment page.
