SG503: Difference between revisions

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{{TM500 | mfg=Tektronix | type=SG503 | function=250 MHz leveled sinewave generator | class=signal generator | image=sg503.jpg | introduced=1974 | discontinued=1993 |
{{TM500 | mfg=Tektronix | type=SG503 | function=250 MHz leveled sinewave generator | class=signal generator | image=SG503 Front Early.jpg | introduced=1974 | discontinued=1993 |
manuals=
designers= |manuals=
* [http://w140.com/smb/SG503_SM.pdf Tektronix SG503 Manual (OCR, PDF)]
* [[Media:070-1622-01-1974.pdf|SG503 Instruction Manual 070-1622-01 <br> Early type]]
* [[Media:070-1622-01.pdf|SG503 Manual 070-1622-01 <br> s/n: B010100 through B089999]]
* [[Media:070-6770-00.pdf|SG503 Manual 070-6770-00 <br> s/n: B090000 and up]]
* [[Media:Tek SG503 Wizard Workshop mods.pdf|SG503 Modifications from Wizards Workshop]]
}}
}}
It was primarily intended to be used as an oscilloscope calibration device for measuring bandwidths up to 250 MHz.  Unlike later instruments like the [[SG504]], it does not use a leveling head but was designed and calibrated with high quality coaxial cable (P/N 012-0482-00) to operate as a closely matched system when terminated into a 50 Ω load.
Nine overlapping ranges cover the frequency band from 250 kHz to 250 MHz, with an additional range reserved for a 50 kHz reference frequency.


Nine overlapping ranges cover the frequency band from 250 kHz to 250 MHz, with an additional range reserved for a 50 kHz reference frequency.
It was primarily intended to be used as an oscilloscope calibration device for measuring bandwidths up to 250 MHz.  Unlike later instruments like the [[SG504]], it does not use a leveling head but was designed and calibrated with high quality coaxial cable (P/N [[012-0482-00]]) to operate as a closely matched system when terminated into a 50 Ω load.


The SG503 shows the selected frequency on a 3-digit LED counter.
The SG503 shows the selected frequency on a 3-digit LED counter.
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{{BeginSpecs}}
{{BeginSpecs}}
{{Spec | Frequency | 50 kHz, 250 kHz to 250 MHz in nine ranges  }}
{{Spec | Frequency | 50 kHz, 250 kHz to 250 MHz in nine ranges  }}
{{Spec | Frequency accuracy |  Within ±0.7% of one count of the least significant displayed digit for the indicated frequency }}
{{Spec | Frequency accuracy |  Within ±0.7 of one count of the least significant displayed digit for the indicated frequency }}
{{Spec | Amplitude |  5 mV<sub>p-p</sub> to 5.5 V<sub>p-p</sub> in three decade ranges (terminated into a 50 Ω load)  }}
{{Spec | Amplitude |  5 mV<sub>p-p</sub> to 5.5 V<sub>p-p</sub> in three decade ranges (terminated into a 50 Ω load)  }}
{{Spec | Harmonics | 2<sup>nd</sup> harmonic ≥35 dB down from fundamental, 3<sup>rd</sup> and higher harmonics ≥40 dB down }}
{{Spec | Harmonics | 2<sup>nd</sup> harmonic ≥35 dB down from fundamental, 3<sup>rd</sup> and higher harmonics ≥40 dB down }}
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==Internals==
==Internals==
The SG503 uses two LC Hartley oscillators, one for 100 MHz and above with an air-core inductor, the other for the lower ranges using switched ferrite-core inductors.  Tuning is via a traditional three-section variable capacitor. After filtering, a regulated power amplifier stage (caution: beryllium oxide in transistor cases!) is followed by a peak-to-peak detector for the amplitude control loop, and switchable output attenuators.
The SG503 uses two LC Hartley oscillators, one for 100 MHz and above with an air-core inductor, the other for the lower ranges using switched ferrite-core inductors.  Tuning is accomplished via a traditional three-section variable capacitor. After filtering, a regulated power amplifier stage (caution: [[beryllium oxide]] in transistor cases!) is followed by a peak-to-peak detector for the amplitude control loop, and switchable output attenuators.


The frequency counter is built from a 10131 ECL prescaler followed by 7490 TTL BCD counters and 7-segment decoders (display not multiplexed).
The frequency counter circuit starts with a ÷8 prescaler (SP1670 and 10131 ECL flip-flops) followed by 7490 TTL BCD counters and 7-segment decoders (display not multiplexed).
 
==Notes==
The Tek [[012-0482-00]] cable is made from RG-223 50 Ω double-braid shielded coaxial cable (or equivalent), and is exactly 36" from end-to-end.


==Links==
==Links==
* [http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_500/SG503.htm SG503 @ amplifier.cd] (German) including measurements of cable influence (1 m Belden H-155 as replacement for original cable)
* [https://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_500/SG503.htm SG503 @ amplifier.cd] (German) including measurements of cable influence (1 m Belden H-155 as replacement for original cable)
* [[Media:SG503_P2P_Substitute_REVISED.pdf|SG503 Peak-to-Peak detector substitute]] by John K. Bennett AE0AM
* [https://www.youtube.com/watch?v=oRUtsDIOA40 SG503 Lab Check In and Calibration] by Zenwizard Studios @ YouTube
* [https://www.youtube.com/watch?v=O0E6QeX82LY Tektronix SG503 Refresh and Alignments] by Zenwizard Studios @ YouTube
{{Documents|Link=SG503}}
 
==Prices==
{| class="wikitable sortable"
|-
! Year
! 1979
! 1980
|-
! Catalog Price
| align="right" | $1,325
| align="right" | $1,375
|-
! In 2023 Dollars
| align="right" | $5,600
| align="right" | $5,100
|}
 
According to an [[Media:Tek Schottky Diodes Memo rot.pdf|internal memo]], annual sales were estimated at 1200 units in 1979.


==Pictures==
==Pictures==
'''Early model'''
<gallery>
<gallery>
Sg503.jpg | Early SG503
Tek SG503 early front.jpg              |
Tek sg503 late.jpg | Late SG503
SG503_Front_Early.jpg                  |
Tek SG503 early left.jpg                | Left Internal
Tek SG503 early right.jpg               | Right Internal
Tek SG503 Attenuator Board.jpg          | Attenuator Board Part
Tek SG503 Attenuator Board Top.jpg      | Attenuator Board Top
Early SG503 Attenuator Board Bottom.jpg | Attenuator Board Bottom
</gallery>
 
'''Late model'''
<gallery>
SG503_Front_Late.jpg
Tek sg503 late.jpg
SG503_Left_Late.jpg                    | Left Internal
SG503_Right_Late.jpg                    | Right Internal
Tek sg503 left internal.jpg
Tek sg503 left internal.jpg
Tek sg503 rear internal.jpg
Tek sg503 rear internal.jpg
Tek sg503 front left internal.jpg
Tek sg503 front left internal.jpg
</gallery>
</gallery>
==Components==
{{Parts|SG503}}
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