1967 Tektronix Vectorscope (NTSC) Model 520A

Impressive looking late 60's gear, standard gear in the video broadcast industry for looking specifically at the chrominance signal, and used in conjunction with a waveform monitor to measure the overall characteristics of the video signal.

This vectorscope allows for the X-Y plot of two signals and although dedicated in this case to looking at the 3.58Mhz NTSC sub-carrier in the video signal, possibly it could be modified for another project where X-Y plotting was necessary.

Tektronix Vectorscope

Model 520A

Rack mountable but I have removed the rails

Runs on anywhere from 50V (yes 50V) AC up to 260V Single phase

Current set to run on our 240V single phase supply

I won't go into the specific specifications for this equipment, it is easily available online but only to say that in its day, it was THE test gear to have for examination of the chrominance signal.

COSMETIC CONDITION:

Overall, the case is in great shape - no dents or bad scratching, front panel is clean and all original knobs and switches are present.

The CRT screen is clean and undamaged and fitted with the filter and graticule for NTSC.

Inside, all boards are clean and there have been no modifications made - it is straight out of the late 60's!

Mostly discrete semiconductors although a few 4000 series logic chips are there as well.

Nice metal encased CRT tube - part number 377-0945-01

A couple of high quality Sprague electrolytics although you would have to question their life expectancy after almost 50 years in circuit! They are 240uF 200V & 130uF 300V

Beautifully laced wiring looms, all interconnections colour coded - reminded me a lot of the old PMG cables with the specific colour coding Red-Green-Blue etc with a secondary broken colour on the sheath.

Each sub-assembly board is clearly marked such as the Low Voltage Board, Demodulator board, Sweep board, Driver board etc - great for teaching or training use as it is so well laid out and easy to follow what each section is doing.

Now, the big question - does it work? Well yes and no - there is a fuse on the rectifier board which physically went bad (the end cap fell off!) so the fuse went open. Now I don't have a schematic and the body of the old fuse (still in place) does not have any current rating on it - just 250V

I do NOT have the manual, operating - service or otherwise, although I see others do sell these online for about as much as I am asking for the actual unit!

Its "sister" fuse is rated at 250mA so this "might" be a good replacement for F1502 but that's really just guesswork. Better to put a meter across the terminals and see what current it is drawing and then estimate a suitable fuse (it is a standard fuse not slo blow)