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Electronics => RF, Microwave, Ham Radio => Topic started by: pinball! on November 03, 2024, 07:11:18 pm

Title: 44MHz Modulator
Post by: pinball! on November 03, 2024, 07:11:18 pm

I have the need for a 44MHz AM modulator to do some troubleshooting on TV IF stages. It has to be capable of modulating a full NTSC 6MHz signal at 44MHz. Unfortunately 44MHz is below what normal video modulators can handle. Any ideas? Providing an external carrier frequency is not a problem. I have HP modulators that are unable to go above a few kHz.

Edit: mhz to MHz

Title: Re: 44mhz Modulator
Post by: Bud on November 03, 2024, 07:24:01 pm

mhz is milli Hertz. Maybe this is the issue?

Title: Re: 44mhz Modulator
Post by: pinball! on November 03, 2024, 07:55:26 pm

It was meant as MHz. I can't say I've ever worked in the sub Hz range. Will edit for clarity

Title: Re: 44MHz Modulator
Post by: dobsonr741 on November 03, 2024, 08:18:25 pm

Build or get a MC1374 based modulator. The usual channel 3 and 4 are above your target, detune it, it’s spec’s down to 30MHz. http://www.bitsavers.org/components/motorola/_appNotes/AN-0829_Application_Of_The_MC1374_TV_Modulator.pdf (http://www.bitsavers.org/components/motorola/_appNotes/AN-0829_Application_Of_The_MC1374_TV_Modulator.pdf)