changeset
[eip545b] new blog post on the EIP545B RF Counter
Wed, 20 Dec 2017 23:33:53 +0100
- author
- David Douard <david.douard@logilab.fr>
- date
- Wed, 20 Dec 2017 23:33:53 +0100
- changeset 73
- e80d307aa643
- parent 72
- 9296d8c2339a
- child 74
- 70f45e3ac6d0
[eip545b] new blog post on the EIP545B RF Counter
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/content/eip545b.rst Wed Dec 20 23:33:53 2017 +0100 @@ -0,0 +1,155 @@ +=============================== + EIP 545B RF Frequency Counter +=============================== + +:author: David Douard +:Category: Electronics +:Tags: test equipment, RF, EIP, 545B, counter + + +I recently purchased a broken EIP 545B microwave frequency counter on ebay. It +was very inexpensive (around 150€ delivered), but obviously, non working. + +.. image:: {filename}images/eip545b/closed_unit.jpg + :alt: The EIP 545B RF Counter + +The device was described as "does not power up", an is clearly not in very good +condition. Quite dirty, battered, with the band 2 BNC connector ruined. + +But inside, it was **very** dusty and a bit rusty: + +.. image:: {filename}images/eip545b/inside.jpg + :alt: Once opened, it's very dusty + +The YIG filter looking not so good: + +.. image:: {filename}images/eip545b/rusty_yig.jpg + :alt: The rusty YIG filter + + +I quickly checked, and indeed, nothing happened when I tried to power it up. In +fact, the fuse was blown. So, instead of just give a try with a new fuse, I +decided to disassemble it completely to clean it up, check the power supply +independtly, then inserting the boards one at a time. + + +PSU +=== + +So the first step has been to check wether the PSU is working fine. Overall, it +looks OK: + +.. image:: {filename}images/eip545b/psu.jpg + :alt: The A101 PSU board + +There are many tantalum capacitors in this unit, including on the PSU board: + +.. image:: {filename}images/eip545b/psu_tantalums.jpg + :alt: Tantalum capacitors on the PSU board + +But they seem OK, so I gave it a try with no load, but using a variac to rise +the input voltage slowly: + +.. image:: {filename}images/eip545b/psu_test.jpg + :alt: Testing the PSU board + +I plan to build myself a nice isolation transformer unit using this variac, a +true isolation transformer I have and the power meter shown on this picture, +but that's another story. + +The results are ok so far, voltages are OK. The PSU seems to work just fine. + +Cleaning the unit +================= + +The next step has been to completely disasseble the counter in order to clean +it properly. + +It's a quite simple unit, easy to disassemble, so it took me only a few hours +to do so. + +My only complain is to be obliged to disolder a few wires to disassemble the +components from the back panel. + +I'e washed every part I could in my kitchen sink, with dishwashing soap and a +duster, includind the A100 interconnect board. + +Other PCB board have been cleaned with a small tooth brush, some cloth, and +isopropyl alcohol. + +I also tried to remove a bit of the rust from the YIG filter using some +scotch-brite, but I could not really clean it without disassembling it, and I'm +not sure wether it is safe to open the enclosure of the YIG filter or not (if +it's sealed with special gas for example). Also, I wanted to check if it works +before doing anythno stupid. + +Reassembling and testing +======================== + +Then I started to reassemble the unit, just putting back togother the front +panel, the CPU and the PSU. + +Once powered, nothing happened, the display did not lit... It happened I forgot +to put back the 7805 regulator dedicated to the front panel (and mounted on the +aluminium chassis for heat dissipation). Doh! + +Once fixed, the unit did power up, and reacted to some keys: + +.. image:: {filename}images/eip545b/test_cpu.jpg + :alt: Testing the unit with only the CPU board + +So far so good. Now the time for testing the other boards. + +After inserting all the boards but the optional A102 GPIB board, the unit still +powered up, but the keyboard was mostly unresponsive, and the "remote" led was +lit. Putting back the GPIB board did the trick. + +I also had to plug the 10MHz In/Out switch back (located on the back panel), +since the default (open) position is for "External Reference". + +Now I can interact with the device. In band 3, and I can hear a small noise, +typical for a YIG coil sweeping the range... Good sign! + +Let's put some signal, first a 6MHz on the band 1 input: + +.. image:: {filename}images/eip545b/working_band1.jpg + :alt: Testing a 6MHz signal on band 1 input + +It works! I quickly checked band 2 (using a piece of wire since the connector +is broken), and it seems to work fine. And band 3: + +.. image:: {filename}images/eip545b/working_band3.jpg + :alt: Testing a 1GHz signal on band 3 input + + +I've checked up 2GHz (the max frequency I can generate using my Anristu MG3670B +signal generator. + +A quick test showed that the sensibility is not as expected: could not measure +any signal below -12 ou -13dBm. + + +Next steps +========== + +Next steps for this unit are now: + +1. Finishing the repair, changing the broken BNC connector, the broken fan + (which was in fact the culprit for the blown fuse), as well as, maybe, + removing the rust from the YIG filter. + +2. Make some performance tests and calibrations (as far as I can do using my + equipment). + +3. I also want to try to install the Option 2 (Power Meter). This procedure is + pretty simple (as long as I manage to program a few 2716 EPROMs with my + `MiniPro TL866`_ universal programmer) and has been done by several_ + people_, but always on the 545A model, not the B model. Not sure if I can + use the EPROM images kindly provided by GBPPR_... + + + +.. _people: http://www.qsl.net/n/n9zia//vision/EIP_545A_Modification_Instructions.pdf +.. _several: http://www.simonsdialogs.com/2014/09/eip-545a-microwave-counter-power-meter-upgrade/ +.. _GBPPR: http://www.qsl.net/n/n9zia/vision/ +.. _`MiniPro TL866`: http://autoelectric.cn/EN/TL866_main.html
