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Old 01-21-2017, 05:50 PM
Zenith6S321's Avatar
Zenith6S321 Zenith6S321 is offline
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Join Date: Aug 2010
Location: Charleston, West Virginia
Posts: 303
Downconvert Sweep Gens for early TVs

We can use 45.75 MHz sweep alignment and marker generators to align the early low band IF (18MHz to 38MHz) TVs if we shift their output frequency down (downconvert) to what the TVs need. The parts to do this are easy to get. I made one using a Mini-Circuits TUF-1+ mixer, a cheap DDS (direct digital synthesis) sine wave generator with LCD display and keys, and an RF amplifier module. The parts cost me about $50.00. Attached are a couple of pictures of my B&K 415 low band setup. Here is a list of the components and links to a source (not mine).

Mini-Circuits TUF-1+
PDF: https://www.minicircuits.com/pdfs/TUF-1+.pdf
Source: https://www.minicircuits.com/WebStor...model=TUF-1%2B

Sine wave board source: http://www.ebay.com/itm/AD9850-DDS-F...sAAOSwVL1V-OSt
or
http://www.ebay.com/itm/AD9850-modul...sAAOSwwPhWkcvf

RF Amp board source: http://www.ebay.com/itm/1PC-broadban...sAAOSwo4pYG~A4
or
http://www.ebay.com/itm/Broadband-RF...gAAOSwEzxYQ7z3

The downconverter is connected between the sweep and marker generator RF output and the TV. The TUF-1+ mixer RF input is driven by the sweep and marker generator RF output. The TUF-1+ local oscillator (LO) input is driven by the sine wave generator. The TUF-1+ IF (IF) output drives the RF amp board input. The RF amp output drives the TV sweep gen input point. I may replace the RF amp output coupling capacitor with a higher voltage one, just in case.

I will try to post some more pictures and waveforms, but I have to delete some old VK posted pictures to make room for them.
Attached Images
File Type: jpg B&K415-LowBandSetup.jpg (119.4 KB, 75 views)
File Type: jpg downconverter.jpg (72.5 KB, 72 views)

Last edited by Zenith6S321; 06-03-2017 at 07:49 PM.
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