EIP 545A Microwave Counter: power meter upgrade

This time, not really a repair, but an upgrade.

Every lab or repair shop dealing with really high frequency circuits needs one: a microwave counter. The EIP 54x series has certainly been (and still is) one of the workhorses of the industry. EIP is now Phase Matrix, still selling counters. But I guess, not an easy tasks – there are quite a few of the EIP counters around, and they do have some little issues with tantalum capacitors, etc, but all in all, the EIP counters are really marvelous instruments, rock solid.

The 545A:
eip 545a counter

In my own shop, there are two 545A counters (18 GHz, N connector), and also a 548A, which is similar, but covers up to 26.5 GHz (3.5 mm connector). The 548A can go to frequencies as high as 110 GHz, with some external mixers. While these have provided good service over the years, they are all lacking ‘option 2’, the build-in power meter. At microwave frequencies, having a combined power meter and counter has a considerable advantage – no need for changing cables, no need for splitters or couplers – just the push of a button. And not always do you want to connect a circuit under test to a valuable 18 GHz+ spectrum analyzer or measurement receiver…

Fortunately, there are clever people around, at the Green Bay Professional Packet Radio club (“GBPPR”), which kindly provide the ROM images and some circuit modification info on the web – to convert a regular 545A, to an option 2 545A!

Well, first we need to collect some parts, a low capacity Schottky diode (HP 5082-2835, 1 pF max.; original EIP circuit uses a different kind, but really any low capacity Schottky will work), a DM8136N (a comparator/address decoder), a 74LS244 buffer, and an AD7524JN (8 bit DAC) – plus, a 10k resistor. Except for the DM8136N, nothing uncommon at all.

The only tricky part, at least here – the 2516 EPROMs. These aren’t accepted by any of the programmers around, and they need a high programming voltage. So first, put together a little programmer that attaches to an ATmega32L, and with the data transfered by USB.

2516 eprom programmer
It’s really crude – I don’t anticipate a lot more 2516 EPROMs that need programming, except for the EIP….

The second type, they are 2532 EPROMs (I had some 2532A around which are working perfectly fine, just lower programming voltage. The 2532As – they can be handled by most 2732 programmers, with a little socket adapter (2532 and 2732 have different pinouts!).

After fiddling around with the EPROMs, the little programmer, the adapter sockets – a few hours later – that’s now the set of parts:
eip option 2 upgrade parts

These are the boards, A105 and A107, with the parts installed – red rectangles: additional parts; yellow: removed parts (resistors R39 and R40).
eip 545 board modifications

I would suggest to put all parts in sockets, like EIP did. Then you can change your counter back, to non-option 2, should you ever want to.

After a bit of soldering – that what we have – a working option 2 EIP 545A.
eip 545a option 2 power meter working
The power meter can be switched off – if you need the extra digits. Typically, I don’t.

All that is left are the original EIP EPROMs, programmed in San Jose, California. Collectables.

eip original eproms

Any questions, please let me know!

15 thoughts on “EIP 545A Microwave Counter: power meter upgrade”

  1. Hello simon compliments for your work and for the article, i bet it will be helpful to many people…i bought an 548B with some issues, do you have some service manual?thank you Nicola

  2. Nice work!
    Would you consider doing the modification for someone else?
    I am definitely interested.

    1. Sure, just keep in mind I am living in Germany so it is pretty expensive to ship the unit here. Otherwise, I can also offer a set of EPROMs, or can modify the boards only – however then I can’t test the full unit.

  3. Just got an EIP 545A without the power option. Could I purchase a set of EPROMs from you? Also looking for a DM8136N. Some on Ebay but at pirate prices.

    Many thanks,
    Bob Sandness

    1. Hi Bob,
      Unfortunately, just sold the last set of programmed eproms recently, but can program new sets and will also check for the 8136n. Currently on business travel but will check over the next weekend/please remind me by email if I forget. Simon

  4. Thanks Simon. Look forward to following up when you get back. Much appreciate your help.


  5. I have an EIP 545A as well and would be interested in acquiring a chip set. Simon, please let me know if this is a possibility.

    1. Hi Tom, Sure, this is possible. Currently I have not enough 2532A here, but some are on order, so probably I can send you a set late March. DM8136, and 74244, available as well.
      The AD part, no spares at the moment, and the Schottky diode, I have some, do you need this as well?
      If still interested, just send a message to simon@simonsdialogs.com some time mid March.

  6. Do you have a link to the EPROM files for the modification? I have an ancient EPROM programmer that can program 2716’s and 2732’s, but I can’t find the code anywhere.

  7. Dear Simon, thanks for the article. I was using a 2nd hand EIP 548B counter for ages but now it is broken showing error 40 on Bands 3 and 4X. The 1st diagnose was malfunction of EEPROM where Options and YIG correction data are stored, but counter doesn’t work with the EEPRPM copied from working counter of the same type showing the same error. It seems there is something wrong with EEPROM reading or YIG filter control. I would be very helpful to have a service manual, could you help me, please? Best regards Antonin, OK2VMC

  8. Dear Simon, do you have any experience with Option 2 upgrade of EIP 548B counter? Is it also so easy as for 548A type? If yes, I’m strongly interesed in set of EEPROMs and possibly also in DM8136N. Best regards Antonin OK2VMC

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