Tracking generator for HP8591E - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: December 15, 2019, 01:56:59 am
content: Inspired by Kerry Wong's tracking generatorhttp://www.kerrywong.com/2016/01/10/building-a-tracking-generator/I wanted to see how hard would be to add one to either the HP8591E or HP8594E that I own, or to both, but I want to place it inside the SA case. The first thing, I bought an RF mixer. It is a Minicircuits ZX05-83LH-S+, a very tiny but powerful thing.The first tests are encouraging. HP8591E has an output marked "Tracking Gen." coming out from the first converter. It is terminated with 50 Ohm if the TG is not installed. That output is the first LO going from 2.1214GHz to 3.9214GHz and as far as I could measure it with the other HP8594E, up to 2.9GHz, it is flat at about 10dBm.Kerry used an HP 8642B and a doubler to generate the LO 3.6214 GHz that actually goes into the RF input of the mixer.I need something much smaller that can generate 2.1214 GHz and can fit inside the SA. I tried a Windfreak USB Synthesizerhttps://windfreaktech.com/product/usb-rf-signal-generator/It is a very good fit but unfortunately the older version that I have cannot save the settings to use it without PC next power up. On the other hand, it is quite expensive. A more cost effective solution is this one from Banggoodhttps://www.banggood.com/ADF4351-ADF4350-Development-Board-35M-4_4G-Signal-Source-Phase-Locked-Loop-p-1502194.html?rmmds=detail-left-hotproducts__2&ID=6230948&cur_warehouse=CNcontrolled by an Arduino like thishttps://www.banggood.com/3Pcs-3_3V-8MHz-ATmega328P-AU-Pro-Mini-Microcontroller-With-Pins-Development-Board-For-Arduino-p-980290.html?rmmds=myorder&cur_warehouse=CNbut I don't know how good it is. I'll try it when it comes. The good thing about this one, it has external reference input so I can sync it with The SA's reference oscillator.Here are some pictures with the preliminary experiments. I used direct connection from the first converter to the LO input of the mixer, since it is a level 10 mixer and the TG output is right around the right level, the USB Sinth to the RF input and the output is straight from the IF output.I tested a 10.7MHz IF filter, a crystal and a 30dB directional coupler rated 1 - 2 GHz.

author: Miti
author_rank: Super Contributor
timestamp: December 15, 2019, 02:31:11 am
content: Now, this could be usable but I want to make it on a PCB and to add some more elements.I attached a preliminary block schematic, please let me know what you think.- Input pad, together with the amplifier, create an isolator and improves the VSWR at the output of the first LO.- Output amplifier and attenuator will bring the output level to about 0dBm and improve the VWSR. The attenuator could be one of thishttps://www.banggood.com/NC-Attenuator-PE4302-Parallel-Immediate-Mode-p-1167649.html?rmmds=search&cur_warehouse=CNcontrolled by the same Arduino, or a fixed one.- I could use one SA general purpose IO to turn the TG on and off. Not sure how to control a step attenuator though.I'm open to ideas.Edit: Here's a very interesting link regarding tracking generators:https://www.dsinstruments.com/store/products/tg6000-rf-tracking-signal-generator-usb/