Darius Modulator build - UK Vintage Radio Repair and Restoration Discussion Forum

Sean Williams · 21st Sep 2005, 6:40 pm

Hi Darius,

I wondered what sort of insertion loss you measured with your output filters??

I have made the London one, and althogh it does indeed work between 41 and 45 megs I get a very high loss at operating frequency (around 20db)

Has anyone else built these?

Cheers
Sean

Sean Williams · 21st Sep 2005, 8:54 pm

Ok, well, I have built a different filter, with my own component values, much less insertion loss!

Pictures below!

Cheers
Sean

oldeurope · 22nd Sep 2005, 8:25 am

Good morning Sean,
no remarkable losses. Maybe one tuned circuit was not in tune.
Please let me see your filter frequency response!

Attached a few pics of the modulator used in the MK III converter.
Hope it's helpfull.

Kind regards
Darius

oldeurope · 9th Dec 2005, 8:14 pm

Good evening,
for all those who want to build it,
a universal video board kit comes up in january. It contains the vision stages
for the modulator.

A lot of usefull things for vintage tv can be done with this board.
A discription and a schematic will come up soon in an extra thrad.

Kind regards
Darius

21st Sep 2005, 6:40 pm	#1
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,517	Darius Modulator build Hi Darius, I wondered what sort of insertion loss you measured with your output filters?? I have made the London one, and althogh it does indeed work between 41 and 45 megs I get a very high loss at operating frequency (around 20db) Has anyone else built these? Cheers Sean __________________ Engineers make things work and have spare bits when finished

21st Sep 2005, 8:54 pm	#2
Sean Williams Dekatron Join Date: Feb 2005 Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW Posts: 3,517	Re: Darius Modulator build Ok, well, I have built a different filter, with my own component values, much less insertion loss! Pictures below! Cheers Sean Attached Thumbnails __________________ Engineers make things work and have spare bits when finished

22nd Sep 2005, 8:25 am	#3
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: Darius Modulator build Good morning Sean, no remarkable losses. Maybe one tuned circuit was not in tune. Please let me see your filter frequency response! Attached a few pics of the modulator used in the MK III converter. Hope it's helpfull. Kind regards Darius Attached Thumbnails

9th Dec 2005, 8:14 pm	#4
oldeurope Retired Dormant Member Join Date: Dec 2003 Location: Solingen, Germany Posts: 727	Re: Darius Modulator build Good evening, for all those who want to build it, a universal video board kit comes up in january. It contains the vision stages for the modulator. A lot of usefull things for vintage tv can be done with this board. A discription and a schematic will come up soon in an extra thrad. Kind regards Darius