The POWER METER PROM (Option 02 only) contains a logic comparator (U21), a 2K x 8 PROM (U20), and a bus driver (U19).
The logic comparator is connected to the microprocessor address bus, and is configured to decode the 2K address range from 4000 Hex to 47FF Hex.
The comparator output drives the chip select of the PROM and the bus driver.
The PROM contains the Power Meter program as well as the power correction factors.
Bus driver U19 is used as a buffer for driving the microprocessor data bus
The power meter contains 690 correction factors. stored in PROM.
The 150 "power vs power" correction factors compensate for variations from
square law in the detector and power meter circuits. They are divided into
three tables. The first table corrects variations below 10 GHz. The second
corrects variations between 10 and 20 GHz. The third corrects variations above
20 GHz.
The 540 "power vs frequency" correction factors compensate for variations in
the detector output at different frequencies. "Power vs frequency" corrections
cover 0-27 GHz every 50 MHz. ' The power meter is calibrated at the factory
using specialized automatic test equipment.
Recalibration in the field is not recommended.
Has anyone ever tried this procedure on a 545B?
Hi,
54xA Opt.02 circuit doesn't work on 'B' model, the firmware part present in the Opt.02 EPROM is a extension firmware for the 54xA basic firmware and must be the same FW revision.
54xB firmware has already the option parts included, but it is normally disabled, the activation code reside in the CPU card EEPROM memory with the calibration table.
Do you have tried yourself?
I have not found anything (for now) in the manuals (the ones I could find) that would allow me to guess such a thing. For example, the 575B/578B service manual (ref. 5580032) also mention that "The PROM [on A107] contains the Power Meter program as well as the power correction factors."
Also, the A107 board in both manuals (545A and 575B) is referenced as 2020197-0X (with X from 1 to 8 depending on the combination of 10MHz ref and power measurement capabilities).
I also realized that the service manual for the 545A do explain the calibration procedure of the power meter in details (which the SM of the 575B does not).
EIP manuals, not the revisited Phase-Matrix ones available, are extremely confusing in the 'A' to 'B' transition, see the CCN number in first page, in case of 545 models this transition was occurred between CCN# 2009 to 2010 and for 548 between 2309 to 2310, BUT the CCN# 2009 545A (2309 548A) is the same hardware as the 54xB (new boards), the old hardware ends with CCN# 2008 (2308).
No, I have serviced professionally these counters 20 and more years ago.
Small gift:
http://www.ko4bb.com/getsimple/index.php?id=download&file=EIP_PhaseMatrix/EIP_545_548/EIP_545A_Service_Manual.pdf
This manual is for CCNs 2209/2309, usable for your 545B, CPU board is the new p/n 2020215, some layouts are not updated as the potentiometers on A108, but schematic seems to be correct.
I still have a few issues I need to fix:
- I've replaced the CR4 zener diode on A107; it was dead (open), but the sensibility remains too low on band 3 (I can sometimes "catch" a signal at -15dBm or so, but it's unstable). The reference voltages on pin 2 of U14 (LM393 comparator) is now a stable -100mV as described somewhere in the service manual, but the signal detection circuitry is still not working properly. I need to double check the capacitors on this A107 board, since a quick in-place check with a DER DE-5000 LCR meter showed some strange results for some of them (surprisingly, not the tantalum ones, but I'll check theses again with a lead desoldered from the board).
Have you checked the calibration on the YIG bandpass filter? If it's out of adjustment, the signal won't get through to the rest of the system or will be badly attenuated. I have a unit that seems to be made of pieces from multiple systems. The YIG filter was about as far out of adjustment as it could be!
Ed
Now i need to figure out where the calibration curves are stored in the memory. I don't think it's located at the same address as it was on the 545A (0x4000 in the EPROM that can be installed on A107) since the ROM on the CPU board do have content in this 0x4000->0x47FF mem area.
It might even be located in the EEPROM.
- When I power the device, it's set with a 200MHz offset and only 5 digits of resolution. I guess this is the part of the "SPECIAL WB68" version of the firmware I have, but I find it quite annoying.
Just realized HighPrecision wrote a few posts back the PM calibration table is in the EEPROM... doh! Whatever, I still need to find where.
I've found the tests vector table in the firmware, and there is no other (undocumented) test than the ones listed in the service manual (1 up to 11, 90 and 91). Could have been a 92 or any other value to enter a PM calibration menu but it seems no such menu exists... So one have to burn the values in the EEPROM somehow.
Special WB68 is a BAND 3 Low end frequency extension to 0.6GHz (600MHz) with reduced specs for sensitivity and power meter dynamic range.
Frequency offset and resolution setting have not to do with this special option, in the EEPROM there are saved the instrument power-on defaults.
As I said the power meter calibration is NOT part of the standard calibration procedure, there is no related TEST xx for this.
The EEPROM on CPU board is allocated from 0x0800 to 0x0FFF
Power meter calibration table start at 0x0810
YIG DAC calibration table start at 0x0C00, but I have no idea if the special option WB68 start at this location (shifted data ?).
You can use TEST 10 to modify the EEPROM locations, or via GPIB with TA10 command, obviously the write-protect switch should be disabled.
I suggest to save the entire EEPROM before any attempt to change data.
Another question, maybe I missed this in the service manual, but is there a procedure to check wheter the YIG calibration is correct?
I was thinking about how I can check this (to address my sensibility problem), and I'm not sure what's the best way of doing this verification.
Don't think I can force the YIG to stay centerered at a given freq, without scanning (then inject a know signal and measure the power ouput from A203. Can I? Setting the low/high freq limits to the same value maybe?
David
Another question, maybe I missed this in the service manual, but is there a procedure to check wheter the YIG calibration is correct?
A quick method only to verify if the YIGF is correctly centered, is to inject a small bipolar current into feedback node of U3 OP-Amp on A108 board, in example: a potentiometer between +12V and -12V, the wiper connected with a reasonable high value resistor in series to the (-) input of Op-Amp.
Thanks a lot. Pretty obvious once one does look at the schematics of the YIG driver... I'll give a try ASAP.
Another weak point maybe the YIG current sense resistor (the big one on A108) is out of tolerance.
Special WB68 is a BAND 3 Low end frequency extension to 0.6GHz (600MHz) with reduced specs for sensitivity and power meter dynamic range.
Frequency offset and resolution setting have not to do with this special option, in the EEPROM there are saved the instrument power-on defaults.
WB-68 B3 .6GHZ to 20 GHZ
600 MHZ to 1 GHZ 0 to -20 dBm
1 GHZ to 20 GHZ +5 to -20 dBm
BCD remote programming (this is a special on a 545B)
GP-IB (option 08)
instrument configurated with BCD interface. GP-IB board
and rearpanel cable physically located in unit.
BCD to GP-IB and vice versa can be done within 15 min.
That's all, this option is possible ONLY on 545B and not on a 548B, the extra space for YIG DAC calibration (to 26.5GHz) is used for this low end extension, probably data shift as I said.Code: [Select]instrument configurated with BCD interface. GP-IB board
and rearpanel cable physically located in unit.
BCD to GP-IB and vice versa can be done within 15 min.