EIP 575 microwave counter

[feedback.loop]

A look inside of EIP 575 microwave counter with high stability time base (option 04) and basic tests:

https://youtu.be/03u4jA9E_Yo

[Vgkid]

Thanks for the video. Interesting how those leds are in sockets.

[wn1fju]

Keep an eye on the tantalums!  I recently got the virtually identical EIP 578 model and ended up pulling all the 10 uF tants out (about 27 of them) because 15 of them were shorted/burned, including some inside the band 3 RF module.  All the 33 uF tants were fine and one of the 1 uF tants was physically cracked in half (no burn marks).  Bad batch perhaps?  After rehabilitation, I really like this counter, especially the power meter option.

[feedback.loop]

Keep an eye on the tantalums!  I recently got the virtually identical EIP 578 model and ended up pulling all the 10 uF tants out (about 27 of them) because 15 of them were shorted/burned, including some inside the band 3 RF module.  All the 33 uF tants were fine and one of the 1 uF tants was physically cracked in half (no burn marks).  Bad batch perhaps?  After rehabilitation, I really like this counter, especially the power meter option.

I didn't notice any problems with tantalums there. I should have looked inside the rf module in the video, but somehow it didn't occur to me at the time.
Unfortunately, mine doesn't have the power meter option. Is it a good alternative to dedicated power meters with very expensive external sensors?

[bitseeker]

Thanks, I quite enjoy your repair vids. First time I've seen one of these counters. Gotta love it when "not working" ends up being a loose connection. I ran across a power supply that seemed to be unstable, but it ended up being just a loose connection between the analog board and the metering display.

[wn1fju]

You asked, "Is it a good alternative to dedicated power meters with very expensive external sensors?"

It was for me, because as you said, the power meter sensors are quite pricey.  The power measurement in the EIP 575/8 pretty much works over the range of the basic counter - from about -30 dBm to +10 dBm.  So it may not be quite as flexible as a dedicated power meter.  But at least against my various signal generators, it seems quite accurate (well less than 1 dB).

I forgot to mention in my previous post, that these are "source locking" counters.  When I first got mine, I thought, "what is source locking and why would I ever need it?"  Turns out to actually be quite useful.  The basic idea is if you have, for instance, a cheap function generator (or synthesizer) with an external VCO port.  You can feed the EIP (back panel output) into the VCO input, and then feed a tap of the generator's output back to the EIP input.  Punch in the frequency you want on the EIP and the EIP will attempt to adjust the VCO until the generator locks to your desired number.  It seems like magic, but really works well.  With your EIP unit with the OCXO, you now have frequency stability for your cheap generator.  There is a limitation on the frequency resolution that you can enter into the EIP (something like 10 kHz if I remember correctly), but if you are trying to externally tune an oscillator via a DC level into its VCO port, it sure beats hooking up a DC supply and hoping it doesn't drift much. 

[feedback.loop]

I forgot to mention in my previous post, that these are "source locking" counters.

Not only that. As I understand, it can measure frequency of one signal in the presence of other signals. You can set a frequency range in the form of low and high limits. I haven't tried that myself. Have you?

[wn1fju]

I hadn't tried the frequency limits as yet, but I just did.  Tee-ed together two sig gens at 1.5 GHz and 2.1 GHz, -10 dBm each.  Fed the combination into the EIP and set the frequency limits first to 1.4/1.6 and then 2.0/2.2 GHz.  As expected, it pulled out the individual signals.  Without the limits, the YIG filter just tunes to the maximum signal it finds.  So in many cases, you probably don't need to use the limits if your interest is in a stronger signal in the presence of an unwanted weaker one. 

To summarize, I encourage anybody reading this thread who is interested in a (used) microwave-capable counter to seriously consider the EIP 575 or 578.  For some reason, few people seem to appreciate the EIP brand and these things often go very inexpensively on eBay.  EIP made a bunch of different models including their "autohet" line which has a slightly different tuning mechanism at microwave.  I have their 351D autohet model, but I think the 575/8 series is much better.  I also have an HP 5342A microwave counter, but I would definitely recommend the EIP over that.

[joeqsmith]

Looks good.  Should provide you many years of service.   

[edpalmer42]

I have an EIP 545A counter.  It also has the frequency limits feature.  If you take your favorite signal generator and put the amplitude as high as possible, you might find that you can measure the second and maybe third harmonic of the signal.  It's a very nice feature when looking at a complex signal.

[charlyd]

@ feedback.loop   option 2 the power measurement should be an easy to build in option place some sockets.  1x dac and an eprom and some other chips i am right. on one of the existing board.

[charlyd]

I am looking for someone who can burn these 6 eproms for me.. 2x TMS2516  and 2X TMS2532   my wellon VP390 doesn t support them.

please send me PM If you can burn them, so i can send you the files.

[dxl]

Not sure whether that's still interesting for you, but i had the same Problem that i had no eprom writer that can handle the 2516/2532 types of EPROMs. What i did was concatenated the -01,-02,-03,-04 eprom images into one image, and burned that into a 27128. I had to wire a few additional address lines (A12 + A13) to the 27128 and picked up the OE pin directly from the input of the address decoder for the 4 2532.

For the 2516 EPROM i took a 2732 which works well, just had to write the image twice because it's double the size.

So my 575 now has Option 02 :-)

The only bad tihng besides the hacky touch is that the 27128 is a bit larger than the PCB.

The A12,A13 + CS line can be picked up from the 74139 nearby, Pin 1 - CS, Pin 2 A12, Pin 3 A13.