UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - PIN diode band switching yaesu ft-767

G0HZU_JMR · 18th Feb 2021, 9:38 pm

Hope it all performed well today. If it helps at all I quickly loaded the circuit components into a simulator for the 0.5-1.5MHz filter range. The simulator is set for 450 ohm ports and this does seem to match well with the filter design. The plot shows the impact of the T attenuator when it is fitted (red trace) and when it is removed (green trace). It does show the expected response across 0.5-1.5MHz and the attenuator does introduce the expected 21dB attenuation.

It's good that all the 1SS83 diodes appear healthy. The 1SS83 has a max reverse recovery time of 100ns compared to the 4ns of the faster 1N4148. I think the slowness of the 1SS83 will help a bit with distortion across a fair bit of the HF band.

18th Feb 2021, 9:38 pm	#37
G0HZU_JMR Dekatron Join Date: Sep 2010 Location: Cheltenham, Gloucestershire, UK. Posts: 3,077	Re: PIN diode band switching yaesu ft-767 Hope it all performed well today. If it helps at all I quickly loaded the circuit components into a simulator for the 0.5-1.5MHz filter range. The simulator is set for 450 ohm ports and this does seem to match well with the filter design. The plot shows the impact of the T attenuator when it is fitted (red trace) and when it is removed (green trace). It does show the expected response across 0.5-1.5MHz and the attenuator does introduce the expected 21dB attenuation. It's good that all the 1SS83 diodes appear healthy. The 1SS83 has a max reverse recovery time of 100ns compared to the 4ns of the faster 1N4148. I think the slowness of the 1SS83 will help a bit with distortion across a fair bit of the HF band. Attached Thumbnails __________________ Regards, Jeremy G0HZU