UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Directional coupler

Radio Wrangler · 28th Nov 2017, 1:23 am

Ah, I just spotted most of "2nd LO" so the LO is probably fixed and the sampler is for a harmonic lock PLL to stabilise it. The printed couplers are cheap, so tek have used a couple more instead of transformers for the sampling diode, so they may well be maximally-coupled 3dB hybrids. As could be the two couplers used to peel off some LO2 for the sampler and to split the drive to the mixer and to the aux output (part of the LO set provided for a tracking generator most likely so the same drive level as the analyser mixer would seem useful.

David

28th Nov 2017, 1:23 am	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,874	Re: Directional coupler - terminated and unterminated Ah, I just spotted most of "2nd LO" so the LO is probably fixed and the sampler is for a harmonic lock PLL to stabilise it. The printed couplers are cheap, so tek have used a couple more instead of transformers for the sampling diode, so they may well be maximally-coupled 3dB hybrids. As could be the two couplers used to peel off some LO2 for the sampler and to split the drive to the mixer and to the aux output (part of the LO set provided for a tracking generator most likely so the same drive level as the analyser mixer would seem useful. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done