It is located approximately in the middle of the board. Remove the top and bottom covers and turn the IC-765 up-side down. In order to do the PBT mod you need an additional 1N914 or 1N4148 small signal Si diode, and you have to access the main PCB in the bottom of the IC-765. You can also watch the video in high definition on my YouTube channel. I have tried to demonstrate the difference between IF-shift and PBT by recording the audio spectrum: Depending on how the shift is adjusted, the passband narrows from the high end or from the low end. The net effect is that the passband does not move but narrows down. On the other hand, PBT shifts the passband of two different IF filters (typically 2nd and 3rd IF) so that the amount the passbands overlap changes. The pass band width, however, does not change. Traditionally, IF-shift shifts the local oscillators, which effectively moves the pass band of the IF filter in frequency. What’s the difference between IF-shift and PBT? This mod is described in the VE3HUR IC-765 notes and reproduced here with some illustrative pictures, as well as a video demonstrating the difference between PBT and IF-shift ![]() ![]() There is, however, a simple mod originally designed by Gerd Henjes, W2ISB, which allows the IF-shift button to tune the passband while the IF-shit button is in OFF position. As you may already know, the IC-765 has IF-shift but no passband tuning.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |