Adding a Frequency Counter Output

 

The E-200D has a built-in crystal marker for setting the output frequency.  It works pretty good, but I like using a frequency counter.  A BNC jack can be added to the left side of the case so that you can monitor the output frequency with a frequency counter. 

You must be very careful to maintain proper shielding.  If not done correctly, you will cause signal to leak out, which can make it impossible to align sensitive receivers.   

Parts Required

Copper foil can be obtained from Techni-Tool www.techni-tool.com.  Their part number is 758ST1436.

The SMA cable assembly listed above has a double shield.  If you don't use this particular cable then it may be necessary to cover the cable with copper foil to improve the shielding (see text).

 

1.  Disassemble your unit per the instructions located on the main page.  Do not remove the main shield cover yet.

 

2.  Look at the internal guts from the left side of the generator.  You will need to drill a hole in the main shield cover near the upper-left corner, big enough to mount the SMA bulkhead connector.  Mark the desired spot, then remove the shield cover and drill the hole. 

 

3.  Install the SMA connector onto the main shield cover as shown in the photo below.  It's a good idea to put some Loctite onto the threads so that the connector does not come loose.  

 

      Here is a picture:

 

 

 

 

 

4.  Solder a short piece of the RG174/U coax cable to point "D" on the oscillator board (see photo below).  There is a ground pin right next to pin D, solder the cable shield to the ground pin.

 

 

 

 

 

5.  Solder the other end of the RG174/U coax cable to the SMA connector.  Do not solder the shield, just solder the center conductor to the pin of the SMA connector.  (shields work best when they are connected on only one end)

 

6.  Install the shield cover back in place.

 

7.  Drill a hole in the left side of the case, towards the lower rear.  Mount the BNC connector in the hole (see the picture at the end of this procedure for the approximate location).  Although a BNC connector with a square flange can be used, one with a round flange will be easier to install.  If you have Loctite, put some on the threads so that it does not come loose. 

 

8.  Install the chassis (the "guts") back into the case but do not install the cover plate yet.

 

9.  You must now cut the SMA cable assembly (you only need half of it).  Screw one end of the cable onto the SMA connector, then run the cable down to the BNC connector.  Use a marker to mark the cable at the BNC connector, then cut the cable.  Be careful not to cut it too short! 

 

10.  Strip the end of the cable and solder the center conductor to the center pin on the BNC connector.  Do not connect the shield.

 

11.  Solder a #16 wire to the ground lug of the BNC connector.  Solder the other end to the copper chassis near the meter.  The exact location is not critical.  Keep the wire as short as possible.  Here is a picture of the exposed connection:

 

 

 

 

12.  Now take some copper foil and wrap it around the exposed connection.  Make sure that the foil does not touch the center pin of the BNC connector.  You can put a piece of electrical tape over the wire to prevent any shorts.

 

13.  Solder a short piece of wire from the ground lug of the BNC connector to the copper foil to make sure the foil gets a good ground.  Here's a picture of the completed connection:

 

 

 

That's it!  Here's what it looks like when you're all done:

 

 

 

 

 

If during alignment of a receiver you find that you cannot get the output of the E-200 low enough, try these in the order listed:

 

a.  Try wrapping the coax around a ferrite core (the coax on the output of the generator, not the coax for the frequency counter).  For details, refer to the "output hints" on the main page.

 

b.  Try disconnecting the frequency counter.  If it is then OK, you are getting signal leakage through the counter connection.  Try using a shorter piece of coax to the frequency counter, and position the frequency counter away from the radio.  You could also try wrapping the coax from the frequency counter around a ferrite core.

 

c.  If there is still too much signal even with the frequency counter disconnected, then remove the cover plate and unscrew the SMA connector.  If this fixes the problem, then you are getting signal leakage from the SMA cable.  Make sure the connection at the BNC connector is completely wrapped with copper foil.  If yes, then it will be necessary to wrap the SMA cable with copper foil as well.  This is especially true if you did not use the double-shielded cable that was suggested in the parts list.  When wrapping the cable with foil, do not try to spiral the foil 'round-and-'round the cable.  Instead, cut a long strip of foil and lay it along the length of the cable, then wrap it around the cable.  Lightly solder the foil to the existing foil at the BNC connector.

 

d.  If there is STILL too much signal, then congratulations on having a very sensitive receiver! (and I'm out of ideas!)