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How To Convert a set of Wacom WP-604, WP-604-A, WP-604-B, WP604-C and WP-604-D Duplexer to work on the 6 meter amateur band 50-55 MHz
How To Convert a set of Wacom WP-604, WP-604-A, WP-604-B, WP604-C and WP-604-D Duplexer to work on the 6 meter amateur band 50-55 MHz
10-09-2016, 04:13 PM
Here is how I modified my WP-604-C and WP-604-D to work on the Ham / Amateur 6 meter band.
I have a set of Wacom WP-604-C and a set of WP-604-D-6-SP that I have converted / modified to work on the 6 meter amateur band 50-55 MHz.
My repeater pair has 1 MHz separation. Here is how I did it.
These instructions are intended to aid in the conversion of a WP-604-D to a 640-E. They are not intended to be precise. You will need to have some skill at
soldering copper pipe.
Conversion of WP-604-D to WP604-E
1. Remove center conductor assembly from cavity and disassemble. Be careful not to damage the finger-stocks.
In the picture below the top conductor is modded for 6 meters 50-55 MHz
the middle conductor is a stock WP-604-D 45-50 MHz
The bottom conductor id from a WP-604-C 40-45 MHz
2. Unsolder the bushing and end plug on the F.C.C. (fixed center conductor) and remove.
3. Remove appropriate amount of the F.C.C. to make the total length of the tube 53 inches long. F.C.C. MUST be shortened from the top, do not cut the end
that has the finger-stock.
4. Resolder the bushing in place at 1-3/4 inch from the top end of the F.C.C to the bottom of the bushing threads.
In the picture below the top is the original and the bottom is a modified conductor. Notice the lower bushing location.
5. Resolder the end plug in the F.C.C.
6. Unsolder the Invar rod from from the end plug on the M.C.C (moveable center conductor) and slide out.
7. Measure from the threaded end of the Invar rod 65.5 inches, cut off to make the Invar rod 65.5 inches long overall.
8. Resolder the Invar rod onto the end plug of the M.C.C.
9. Reassemble center conductor assembly being careful not to damage the finger-stock.
10. Make an index mark on the bottom of the can and side of the can. Remove the bottom of the can by drilling out the three rivets then using a hammer lightly
knock on one side of the bottom to knock it sideways then remove from bottom of can.
11. Remove the inner brace by removing the two screws on the side of the can and pull out the brace and save the screws.
12. Now if you have the Wacom WP-604-A, WP-604-B or the WP604-C duplexers the cans are 80 inches tall and need to be cut down to 72 inches tall.
if you prefer not to cut the height of the cans you can move the bottom of the can up inside of the can to make the can internal cavity the same as
a 72 inch can. Do not install the bottom of the can yet.
13. Measure down from the top of the can 50 inches and mark and drill two new holes opposite of each other to mount the inner brace.
14. Reinstall the inner brace at the 50 inch holes with the two screws saved earlier.
15. Insert the center conductor assembly into the cavity being careful not to damage the inner brace. Torque the bushing to approx. 100 Ft-Lb.
16. Reinstall the bottom of the can using your index mark and install new rivets or screws to secure it in place. If you had to shorten the can then you will
need to drill new holes in the bottom of the can to secure it.
The important interconnect cables for 50-55 MHz:
37 inches of RG-214 with UHF connectors measured tip to tip.
This is for the cavity to cavity and cavity to antenna tee.
Adjust cable lengths on stubs to get more tuning range of the notches.
Approximate stub cable starting point:
High Pass side is direct stub attachment or as short as possible.
Low Pass side is is 4 inches.
In the picture below you can see the low pass side notch . The right side can is original and the left side is modded.
In the picture below you can see the notch for the high pass side. On the left you can see the direct connection and on the right you can see the original.
Here is the inner brace.
Here on the ow pass side you can see the can on the left is the original notch adjustment and
on the right the shorter coax will make a one MHz separation possible.
Here on the right you can see the original high side pass notch filter and
on the left you can see the modified direct connect connection for the notch.
10-09-2016, 04:13 PM
Here is how I modified my WP-604-C and WP-604-D to work on the Ham / Amateur 6 meter band.
I have a set of Wacom WP-604-C and a set of WP-604-D-6-SP that I have converted / modified to work on the 6 meter amateur band 50-55 MHz.
My repeater pair has 1 MHz separation. Here is how I did it.
These instructions are intended to aid in the conversion of a WP-604-D to a 640-E. They are not intended to be precise. You will need to have some skill at
soldering copper pipe.
Conversion of WP-604-D to WP604-E
1. Remove center conductor assembly from cavity and disassemble. Be careful not to damage the finger-stocks.
In the picture below the top conductor is modded for 6 meters 50-55 MHz
the middle conductor is a stock WP-604-D 45-50 MHz
The bottom conductor id from a WP-604-C 40-45 MHz
2. Unsolder the bushing and end plug on the F.C.C. (fixed center conductor) and remove.
3. Remove appropriate amount of the F.C.C. to make the total length of the tube 53 inches long. F.C.C. MUST be shortened from the top, do not cut the end
that has the finger-stock.
4. Resolder the bushing in place at 1-3/4 inch from the top end of the F.C.C to the bottom of the bushing threads.
In the picture below the top is the original and the bottom is a modified conductor. Notice the lower bushing location.
5. Resolder the end plug in the F.C.C.
6. Unsolder the Invar rod from from the end plug on the M.C.C (moveable center conductor) and slide out.
7. Measure from the threaded end of the Invar rod 65.5 inches, cut off to make the Invar rod 65.5 inches long overall.
8. Resolder the Invar rod onto the end plug of the M.C.C.
9. Reassemble center conductor assembly being careful not to damage the finger-stock.
10. Make an index mark on the bottom of the can and side of the can. Remove the bottom of the can by drilling out the three rivets then using a hammer lightly
knock on one side of the bottom to knock it sideways then remove from bottom of can.
11. Remove the inner brace by removing the two screws on the side of the can and pull out the brace and save the screws.
12. Now if you have the Wacom WP-604-A, WP-604-B or the WP604-C duplexers the cans are 80 inches tall and need to be cut down to 72 inches tall.
if you prefer not to cut the height of the cans you can move the bottom of the can up inside of the can to make the can internal cavity the same as
a 72 inch can. Do not install the bottom of the can yet.
13. Measure down from the top of the can 50 inches and mark and drill two new holes opposite of each other to mount the inner brace.
14. Reinstall the inner brace at the 50 inch holes with the two screws saved earlier.
15. Insert the center conductor assembly into the cavity being careful not to damage the inner brace. Torque the bushing to approx. 100 Ft-Lb.
16. Reinstall the bottom of the can using your index mark and install new rivets or screws to secure it in place. If you had to shorten the can then you will
need to drill new holes in the bottom of the can to secure it.
The important interconnect cables for 50-55 MHz:
37 inches of RG-214 with UHF connectors measured tip to tip.
This is for the cavity to cavity and cavity to antenna tee.
Adjust cable lengths on stubs to get more tuning range of the notches.
Approximate stub cable starting point:
High Pass side is direct stub attachment or as short as possible.
Low Pass side is is 4 inches.
In the picture below you can see the low pass side notch . The right side can is original and the left side is modded.
In the picture below you can see the notch for the high pass side. On the left you can see the direct connection and on the right you can see the original.
Here is the inner brace.
Here on the ow pass side you can see the can on the left is the original notch adjustment and
on the right the shorter coax will make a one MHz separation possible.
Here on the right you can see the original high side pass notch filter and
on the left you can see the modified direct connect connection for the notch.
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