Many years ago, I did a modification to my FT1000D to reduce the internally generated diode noise as well as to reduce the radios' susceptibility to strong broadcast band mixing products. I have previously published the modification for the FT1000MP and have had a lot of positive feedback from that modification, so in response to a number of queries about whether the MP mod would work on the FT1000D, I have decided to publish my mod for the FT1000D and FT1000 as well. The replacement diodes that I have used are the HP 5082-3081 Pin Diodes. This type of PIN diode was carefully chosen and provides the best performance. I DO NOT recommend substitution of any other kind of PIN diode as the 5082-3081 provides the lowest distortion by a significant margin!!! The HP 5082-3081 can be obtained from Allied Electronics and Newark Electronics as well as several other companies.
The diodes are not cheap, but their improved performance more than justifies the cost!
The diodes on the RF unit to replace are:
Main Receiver BandPass Diodes:
Main Receiver Preamp Bypass:
Main Receiver Preamp Switching:
Sub Receiver BandPass (BPF1):
The theory of operation of this mod is discussed in my FT1000MP Receiver Noise Reduction.