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FERNSEH · 4th Dec 2020, 1:34 pm

The attachments show an early ETF modulator. The example I have here required considerable modification before it would work.
The MC1374 was designed for negative modulation systems, that being the case a separate sync tip clamp is used to so that the sync tips can reference to zero modulation. An emitter follower is introduced between the input amplifier and the input pin of the MC1374. Seems that the IC demands a low impedance drive.
The carrier oscillators can be modified to crystal resonators.
Modulator will work on channel B4 frequencies.

Information about the MC1374.

https://www.circuitspecialists.com/c...27/mc1374p.pdf

DFWB

4th Dec 2020, 1:34 pm	#7
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: System A Ch1 modulator using MC1374. The attachments show an early ETF modulator. The example I have here required considerable modification before it would work. The MC1374 was designed for negative modulation systems, that being the case a separate sync tip clamp is used to so that the sync tips can reference to zero modulation. An emitter follower is introduced between the input amplifier and the input pin of the MC1374. Seems that the IC demands a low impedance drive. The carrier oscillators can be modified to crystal resonators. Modulator will work on channel B4 frequencies. Information about the MC1374. https://www.circuitspecialists.com/c...27/mc1374p.pdf DFWB Attached Thumbnails Last edited by FERNSEH; 4th Dec 2020 at 1:40 pm.