UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 6-gang FM stereo tuner heads

Radio Wrangler · 22nd Nov 2022, 6:48 pm

9kHz is a value decided upon as both a lower limit for EMC measurements which were legislated in Germany and later became European requirements. Also 9kHz is one of the specified EMC measuring bandwidths, though there is no causal relationship.

The 9kHz limit is essentially the DC block capacitor. Some analysers don't have one and their first mixer really does go down to DC. You have to be very careful with these instruments like the HP8568A/B

How low you can go without a DC block is a function of your narrowest resolution bandwidth allowing you to resolve close to the IF crossing (zero hertz response) as well as the LO phase noise at that offset/IF bandwidth. THe 8568 is spec'd down to 200Hz.

David

22nd Nov 2022, 6:48 pm	#252
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,901	Re: 6-gang FM stereo tuner heads 9kHz is a value decided upon as both a lower limit for EMC measurements which were legislated in Germany and later became European requirements. Also 9kHz is one of the specified EMC measuring bandwidths, though there is no causal relationship. The 9kHz limit is essentially the DC block capacitor. Some analysers don't have one and their first mixer really does go down to DC. You have to be very careful with these instruments like the HP8568A/B How low you can go without a DC block is a function of your narrowest resolution bandwidth allowing you to resolve close to the IF crossing (zero hertz response) as well as the LO phase noise at that offset/IF bandwidth. THe 8568 is spec'd down to 200Hz. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done