========================================
 EIP 545B RF Frequency Counter - Part 5
========================================

:author: David Douard
:Category: Electronics
:Tags: test equipment, RF, EIP, 545, 545A, 545B, 575A, 578A, counter
:series: EIP545B Frequency Counter
:series_index: 5


Thanks to HighPrecision_, I've been able to get a copy of an old version of the
EIP documentation *"Additional Service Information for 5XX CW Counters"*. It's
unfortunately unavailable online, still, it contains a lot of valuable
information.

.. _HighPrecision: https://www.eevblog.com/forum/profile/?u=116109

The part dedicated to verifying the Band 3 Microwave Converter (A203) is as
follows.


Functional verification of the microwave converter
==================================================

If you are experiencing any problems in band 3 mode of the EIP 53X, 54X or 57X
counters, the following procedure can be used to determine whether the problem
is in the microwave convertor or the basic counter.


This note describes the verification of the convertor into functional blocks,
these include:

A. VCO

B. YIG filter and video circuit

C. 15 dB detected RF amplifier

D. VCO power amplifier

E. RF leakage

If any section of the converter does not conforms to the verification
procedure, the convertor assembly is defective and should be returned to the
factory for exchange. If the module performs according to the checkout
procedure, further troubleshooting is required in the basic counter. Please
refer to the manual and to other sections in this binder or consult the factory
for assistance.

=============== ======== ==============================
Models Affected CCN      Applicable Microwave Convertor
=============== ======== ==============================
535 /B          all      2010241-01/03/05
538 /B          all      2010241-01/03/05
545             all      2010137-01
548             all      2010137-02/03
545A            2201     2010137-01
548A            2301     2010137-02/03
545A /B         2202-... 2010241-01/03/05
548A /B         2302-... 2010241-02/04/06
575A            all      2010241-01/03/05
578A            all      2010241-02/04/06
=============== ======== ==============================

The difference between 2010137 and 2010241 convertors is the VCO board
utilized. The difference makes the converter non-interchangeable.

The 2010137-03 is the direct replacement of the 2010137-02.

2010241-:

  :01/02: IF frequency = 125MHz

  :03/04: IF frequency = 127MHz

  :05/06: IF frequency = 127MHz /no check of linearity
          linearity corrected by software (test 90)
          used in 2 MHz units

The following tests can be performed to verify the operation of the microwave
convertor.


VCO verification
----------------

1. Monitor A108 tp 14 (2020198 or 2020200) with DVM (for 2020138 use tp 4).

2. Monitor A109J2 with a spectrum analyzer. Set the center frequency to
   370MHz.

3. Program the VCO for 370MHz trough the keyboard::

      press TEST 1 0
      press 9 8 2 2 1 8 (182218 -- 2 MHz unit)
      press 9 8 2 0 5 0 (182050 -- 2 MHz unit)

   *The VCO frequency at A109J2 should be exactly 370 MHz.* Refer to the following
   table for the appropriate VCO tuning voltage.

   ======== == ==================
   A108 P/N TP VCO tuning voltage
   ======== == ==================
   2020138   4 > -4.00 VDC
   2020198  14 > -4.00 VDC
   2020200  14 + 1.5VDC +/- .25 V
   ======== == ==================

4. program the VCO for 500 MHz trough the keyboard::

     press 9 8 2 2 2 5 (182225 -- 2 MHz unit)
     press 9 8 2 0 0 0 (182000 -- 2 MHz unit)

   *The VCO frequency at A109J2 should be exactly 500 MHz.* Refer to the
   following table for the appropriate VCO tuning voltage.

   ======== == ==================
   A108 P/N TP VCO tuning voltage
   ======== == ==================
   2020138   4 > +9.5 VDC +/- .5V
   2020198  14 > +10 VDC +/- .5V
   2020200  14 + 10 VDC +/- .25 V
   ======== == ==================

5. select test 07 from the front panel::

     press RESET
     press TEST 0 7

   *The VCO should sweep from 370 MHz to 500 MHz in 50 kHz steps with no
   break-up. Any spur should be less than 60 dBc.*

YIG filter and video circuit verification @ 1GHz.
-------------------------------------------------

In order for this test to work, the counter must placed in the test 10 mode
and there should not be any signal applied to the Band 3 input prior to
entering test 10.

1. Monitor terminal E5 of the convertor with the Y channel of an
   oscilloscope trough a X1 proble.

2. Connect the horizontal output of a sweeper to the X input.

3. No input signal to the counter.

4. Turn the counter off and back on again. Tune the YIG to 1 GHz trough the
   keyboard::

     press TEST 1 0
     press 9 8 4 2 0 1 (184201 -- 2 MHz unit)
     press 9 8 4 0 RESET 4 (1840F4 -- 2 MHz unit)

   Input a -20dBm signal sweeping from 900 MHz to 1.1 GHz into the Band 3
   input. Adjust the offset pot on A108 to center the bandpass of the YIG
   filter on the display. Reduce the power to -20dBm. *The detected envelope
   of the filter should be a minimum of 4mV in amplitude with a DC offset
   less than +/- 50 mV.*

   Offset adjustment reference designators

   =================== ===========
   2020138             A108 R14
   2020198             A108 R13
   2020200             A108 R10
   2020200 (2MHz unit) use test 10
   =================== ===========

   2 MHz unit::

     press TEST 10

     a. press 1840XX
     b. every bit will change the center with 2 MHz
     c. goto a. till adj. is done

   :note: data on 1842 most significant ! (value 1 bit = 510 MHz)
          data on 1840 least significant !

15 dB detected RF amplifier on/off verification.
------------------------------------------------

Change the input to 1 GHz, +5dBm. *The detected RF voltage at E5 should be
greater than +4VDC.*

Turn the amplifier off from the keyboard::

  press 9 9 0 1 3 DATA/CLEAR
        1 9 0 1 3 DATA/CLEAR (2MHz unit)

*The voltage at E5 should decrease by a factor of 30.*

VCO power AMP on/off verification.
----------------------------------

1. remove the input signal to the counter.

2. Turn the A203 power amp on trough the keyboard::

     press TEST 1 0
     press 9 8 4 3 3 RESET (1843F -- 2MHz unit)

   *The voltage at E5 should be greater than 10VDC.*

3. Turn the power amp off trough the keyboard::

     press 9 8 4 3 3 7 (184337 -- 2MHz unit)

   *The voltage at E5 should be 0 VDC +/- 50mVDC.*

IF amp and IF treshold verification.
------------------------------------

1. Program the YIG and VCO to count 1 GHz::

     press 9 8 4 2 0 1      ; YIG at 1 GHz
     press 9 8 4 0 RESET 4  ;
     press 9 8 4 3 3 RESET  ; power amp on
     press 9 8 2 2 2 1      ;
     press 9 8 2 0 8 7      ; VCO at 437.4 MHz

   Input 1GHz at -28dBm to Band 3 input connector. Connect the spectrum
   analyzer to the IF output port (J1) of the covertor.

   *An IF signal should be displayed approximately 30 dB above the noise floor
   at apprimately 125 MHz.* Adjust the input signal as necessary to peak this
   signal.

   Remove the analyzer and connect a power meter to the IF output port (J1)
   of the convertor trough a 10 dB path. Monitor terminal E2 on the
   convertor with a scope and *verify the voltage level to be a TTL low*.
   Decrease the input power until the level toggles ta TTL high. *The input
   power level should be between -28dBm and -40 dBm. The IF power should be
   greater than -5 dBm when E2 toggles from TTL low to a TTL high. The IF
   power should ne greater then -4 dBm when E2 toggles from a TTL high to a
   TTL low as input power is increased.*

RF leakage test.
----------------

1. Turn the ocunter off and back on again.

2. Program the YIG to below 500 MHz through the keyboard::

     press TEST 1 0
     press 9 8 4 2 0 0 (184200 -- 2MHz unit)
     press 9 8 4 0 0 0 (184000 -- 2MHz unit)

   Input a +7 dBm signal sweeping from 1 GHz to 18 (26.5) GHz. *The maximum
   measured voltage at E5 should be .5 mV above the offset level noted in
   paragraph B above from 1 GHz to 10 GHz and 1mV above the offset level
   from 10 GHz to 18 (26.5) GHz.*
