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| 1 =============================== | |
| 2 EIP 545B RF Frequency Counter | |
| 3 =============================== | |
| 4 | |
| 5 :author: David Douard | |
| 6 :Category: Electronics | |
| 7 :Tags: test equipment, RF, EIP, 545B, counter | |
| 8 | |
| 9 | |
| 10 I recently purchased a broken EIP 545B microwave frequency counter on ebay. It | |
| 11 was very inexpensive (around 150€ delivered), but obviously, non working. | |
| 12 | |
| 13 .. image:: {filename}images/eip545b/closed_unit.jpg | |
| 14 :alt: The EIP 545B RF Counter | |
| 15 | |
| 16 The device was described as "does not power up", an is clearly not in very good | |
| 17 condition. Quite dirty, battered, with the band 2 BNC connector ruined. | |
| 18 | |
| 19 But inside, it was **very** dusty and a bit rusty: | |
| 20 | |
| 21 .. image:: {filename}images/eip545b/inside.jpg | |
| 22 :alt: Once opened, it's very dusty | |
| 23 | |
| 24 The YIG filter looking not so good: | |
| 25 | |
| 26 .. image:: {filename}images/eip545b/rusty_yig.jpg | |
| 27 :alt: The rusty YIG filter | |
| 28 | |
| 29 | |
| 30 I quickly checked, and indeed, nothing happened when I tried to power it up. In | |
| 31 fact, the fuse was blown. So, instead of just give a try with a new fuse, I | |
| 32 decided to disassemble it completely to clean it up, check the power supply | |
| 33 independtly, then inserting the boards one at a time. | |
| 34 | |
| 35 | |
| 36 PSU | |
| 37 === | |
| 38 | |
| 39 So the first step has been to check wether the PSU is working fine. Overall, it | |
| 40 looks OK: | |
| 41 | |
| 42 .. image:: {filename}images/eip545b/psu.jpg | |
| 43 :alt: The A101 PSU board | |
| 44 | |
| 45 There are many tantalum capacitors in this unit, including on the PSU board: | |
| 46 | |
| 47 .. image:: {filename}images/eip545b/psu_tantalums.jpg | |
| 48 :alt: Tantalum capacitors on the PSU board | |
| 49 | |
| 50 But they seem OK, so I gave it a try with no load, but using a variac to rise | |
| 51 the input voltage slowly: | |
| 52 | |
| 53 .. image:: {filename}images/eip545b/psu_test.jpg | |
| 54 :alt: Testing the PSU board | |
| 55 | |
| 56 I plan to build myself a nice isolation transformer unit using this variac, a | |
| 57 true isolation transformer I have and the power meter shown on this picture, | |
| 58 but that's another story. | |
| 59 | |
| 60 The results are ok so far, voltages are OK. The PSU seems to work just fine. | |
| 61 | |
| 62 Cleaning the unit | |
| 63 ================= | |
| 64 | |
| 65 The next step has been to completely disasseble the counter in order to clean | |
| 66 it properly. | |
| 67 | |
| 68 It's a quite simple unit, easy to disassemble, so it took me only a few hours | |
| 69 to do so. | |
| 70 | |
| 71 My only complain is to be obliged to disolder a few wires to disassemble the | |
| 72 components from the back panel. | |
| 73 | |
| 74 I'e washed every part I could in my kitchen sink, with dishwashing soap and a | |
| 75 duster, includind the A100 interconnect board. | |
| 76 | |
| 77 Other PCB board have been cleaned with a small tooth brush, some cloth, and | |
| 78 isopropyl alcohol. | |
| 79 | |
| 80 I also tried to remove a bit of the rust from the YIG filter using some | |
| 81 scotch-brite, but I could not really clean it without disassembling it, and I'm | |
| 82 not sure wether it is safe to open the enclosure of the YIG filter or not (if | |
| 83 it's sealed with special gas for example). Also, I wanted to check if it works | |
| 84 before doing anythno stupid. | |
| 85 | |
| 86 Reassembling and testing | |
| 87 ======================== | |
| 88 | |
| 89 Then I started to reassemble the unit, just putting back togother the front | |
| 90 panel, the CPU and the PSU. | |
| 91 | |
| 92 Once powered, nothing happened, the display did not lit... It happened I forgot | |
| 93 to put back the 7805 regulator dedicated to the front panel (and mounted on the | |
| 94 aluminium chassis for heat dissipation). Doh! | |
| 95 | |
| 96 Once fixed, the unit did power up, and reacted to some keys: | |
| 97 | |
| 98 .. image:: {filename}images/eip545b/test_cpu.jpg | |
| 99 :alt: Testing the unit with only the CPU board | |
| 100 | |
| 101 So far so good. Now the time for testing the other boards. | |
| 102 | |
| 103 After inserting all the boards but the optional A102 GPIB board, the unit still | |
| 104 powered up, but the keyboard was mostly unresponsive, and the "remote" led was | |
| 105 lit. Putting back the GPIB board did the trick. | |
| 106 | |
| 107 I also had to plug the 10MHz In/Out switch back (located on the back panel), | |
| 108 since the default (open) position is for "External Reference". | |
| 109 | |
| 110 Now I can interact with the device. In band 3, and I can hear a small noise, | |
| 111 typical for a YIG coil sweeping the range... Good sign! | |
| 112 | |
| 113 Let's put some signal, first a 6MHz on the band 1 input: | |
| 114 | |
| 115 .. image:: {filename}images/eip545b/working_band1.jpg | |
| 116 :alt: Testing a 6MHz signal on band 1 input | |
| 117 | |
| 118 It works! I quickly checked band 2 (using a piece of wire since the connector | |
| 119 is broken), and it seems to work fine. And band 3: | |
| 120 | |
| 121 .. image:: {filename}images/eip545b/working_band3.jpg | |
| 122 :alt: Testing a 1GHz signal on band 3 input | |
| 123 | |
| 124 | |
| 125 I've checked up 2GHz (the max frequency I can generate using my Anristu MG3670B | |
| 126 signal generator. | |
| 127 | |
| 128 A quick test showed that the sensibility is not as expected: could not measure | |
| 129 any signal below -12 ou -13dBm. | |
| 130 | |
| 131 | |
| 132 Next steps | |
| 133 ========== | |
| 134 | |
| 135 Next steps for this unit are now: | |
| 136 | |
| 137 1. Finishing the repair, changing the broken BNC connector, the broken fan | |
| 138 (which was in fact the culprit for the blown fuse), as well as, maybe, | |
| 139 removing the rust from the YIG filter. | |
| 140 | |
| 141 2. Make some performance tests and calibrations (as far as I can do using my | |
| 142 equipment). | |
| 143 | |
| 144 3. I also want to try to install the Option 2 (Power Meter). This procedure is | |
| 145 pretty simple (as long as I manage to program a few 2716 EPROMs with my | |
| 146 `MiniPro TL866`_ universal programmer) and has been done by several_ | |
| 147 people_, but always on the 545A model, not the B model. Not sure if I can | |
| 148 use the EPROM images kindly provided by GBPPR_... | |
| 149 | |
| 150 | |
| 151 | |
| 152 .. _people: http://www.qsl.net/n/n9zia//vision/EIP_545A_Modification_Instructions.pdf | |
| 153 .. _several: http://www.simonsdialogs.com/2014/09/eip-545a-microwave-counter-power-meter-upgrade/ | |
| 154 .. _GBPPR: http://www.qsl.net/n/n9zia/vision/ | |
| 155 .. _`MiniPro TL866`: http://autoelectric.cn/EN/TL866_main.html |
