2600/2510 conversion
Plus 12 Conversion
Add The 12 Meter Band To Your HR-2600 Or HR-2510.
If you own a Uniden HR-2600 or HR-2510 and you are only using it on the 10
meter band, you are missing half the fun. Despite popular believe, both
of these radios can be put on 12 meters with ease and without loosing
any of the radio's current features! With this conversion, it is possible
with as few as 7 parts. You retain full access to the 10 meter band, while
gaining additional access to the 12 meter band. The band switching is accomplished
via the front panel dim switch.
Parts:
First let's cover the required parts. Your local electronic parts store
should be able to supply you with the necessary components.
One PC board (1 3/4 by 1 3/4) to mount the parts
onto. (Foil on one side only)
One 5 volt relay. Single pole double throw.
Two trimmer capacitors-pc mount type (6-50pf).
One ceramic disc capacitor (47pf).
One crystal at 21.995 mhz (Load 33 pf,Resis 20,Drive 2 mw,Tolerance .005,
Wire Terminals HC18). [This controls the 10 meter band].
One crystal at 17.995 mhz (Load 32 pf,Resis 24,Drive 2 mw,Tolerance .005,
Wire Terminals HC18). [This controls the 12 meter band].
You will also need a few feet of hook-up wire. (Less than 1/16 in
diameter).
Preparing The Radio:
The conversion is identical on both radios and you begin by turning the
radio upside-down (speaker up) and placing it on a soft surface (towel, rags,
etc.) to prevent any scratches to the case. Disconnect the power lead and
antenna coax from the radio. Remove the upper cover by unscrewing the top 4
cover screws. Place the speaker cover out of the way, off to the side. Turn
the radio so that the front is facing you (although still upside-down).
Most of my references to the radio assume it is facing you.
Plus12.gif
You'll notice that there are two circuit boards visible in the radio. One
larger one which is lower and to the rear of the radio and a smaller higher
board closer to you. Find and remove the 4 screws holding the smaller (upper)
circuit board and the 4 screws on the side of the radio, just above this
circuit board. Once these are removed you will be able to lift the board
up and turn it on its side. Be careful not to break any wires!
Now locate the 22 Mhz crystal (X302). Unsolder
and remove it from the board. In its place, solder two wires, one through
each hole of the old X302 location. Make each wire 2 inches long. Be sure
to have a good contact on the other side of the board!
Locate the DIM switch on the outside front of the radio. Notice on
the inside of the radio that EACH switch consists of 3 sets of 2 parallel
pins. Count down 4 sets of pins from the top, Solder a 12" piece of
wire here. (If the radio were upright, this would be the bottom set of
the DIM switch's pins). Be sure when counting not to miss the top two rows,
they are hard to see up near the top. Once the wire is connected, put the
board back in place and reinstall all of the inside screws. Also, attach
a 5 inch wire under the back right corner screw before tightening it. This
will serve as a GROUND WIRE for later use.
Refer to the next figure for the exact placement
of the parts on the board, and follow the instructions below. Also refer
to the schematic as needed.
Diagram.gif
Schem.gif
Building The Conversion Board:
Insert all of the parts through the
NON FOIL side BUT ALWAYS COUNT THE ROWS AND HOLES FROM THE FOIL SIDE,
STARTING FROM LEFT TO RIGHT. (Ignore the 4 large corner holes).
Insert the two trimmer capacitors first. The parallel ends insert in
the top row, the other end of the capacitors insert in row 3. On the foil
side of the board, find the capacitor pins near the center of row 1 (the
2 closest pins-row 1 holes 4 and 8). Solder the 2 pins using solder bridges
across the foil or use a small piece of wire to attach the two together
and solder.
Next, we'll install the 5 volt relay. It has 6 pins. The 2 that are
separated from the other 4 we will call pins 1 and 2 (left to right facing
pin side of the relay). The center 2 are pins 3 and 4. The bottom two are
pins 5 and 6. Insert the relay between the two caps with pin 1 in row 2
hole 6, pin 2 in row 2 hole 8. Pins 3 and 4 in row 4, pins 5 and 6 will
be in row 5. Turn over the board and solder pin 1 to the foil to hold it
in place.
Insert the 10 meter crystal into row 6, holes 4 and 6. Connect one
lead up to row 3 hole 4 and solder to the capacitor at that point. The
other lead connects at an angle to pin 5 of the relay. Solder. Insert
the 12 meter crystal into row 6 holes 10 and 12. Tie one lead to row 3
hole 12 and solder to the capacitor at that point. Connect the other lead
at an angle to relay pin 6 by using another piece of wire and solder.
Now take the lead that you soldered to the left hole of X302, (front
of radio still facing you) attach the other end to the capacitor at row
1, hole 1 and solder. Take the lead that you soldered to the right hole
of X302, attach the other end through row 2, hole 5, solder to relay pin
number 1 (row 2, hole 6).
Take the Ground lead that you put under the screw earlier and insert
the other end through row 4,hole 10 and solder to relay pin 4.
Finally, take the free end of the DIM switch wire that you had soldered
to the inside front panel and insert it through the perf side of board
in row 4, hole 6. Solder to relay pin 3, row 4, hole 7.
Testing Your Work:
Insulate the bottom of the conversion board with electrical tape to keep
the foil from shorting any of the 2510/2600 parts. Placement of the conversion
board should be as seen in the first figure. Reconnect the antenna and power.
Turn on the radio and press the DIM switch on and off, the relay should
click on and off. If not, recheck your work. With the DIM switch off (Bright)
you will tune across the 10 meter band.
When on 12 meters, the radio still displays 28
MHZ. For example, if you want to tune to 24.95, set the radio to 28.95.
With the DIM switch on (light dimmed) you are really on 24.95 of the 12
meter band. Just subtract 4 MHZ from the displayed number, all of the other
digits will be correct.
This last step should only be used if you experience distortion on
the received signals on the 12 meter band. Take the 47 pf capacitor and
cut the leads to about 1/2 inch. Solder one end to test point 306 (TP306).
This is located to the left and about 1/2 inch in front of X302. You must
have a good contact here! Solder the other end of the capacitor to the
metal can of the coil right behind TP306.
A frequency counter or a local ham can help you tune the radio back
on frequency on each band. Adjust the capacitors to set each band on frequency.
The capacitor connected to the 10 meter crystal, will adjust the 10 meter
band, the capacitor near the 12 meter crystal, adjusts the 12 meter band.
Remember, in the USA, the 12 meter band runs from 24.89 to 24.93 for
cw and 24.93 to 24.99 for phone. And you need at least a General Class
or better to operate the band! 12 meters is an interesting band. Even if
it sounds dead, get on and give a CQ call, it is often wide open long
after 10 meters has died.
Caveat: It is up to you to ensure that the radio
signal output of both bands meet your country's requirements for purity of
emissions. If you determine that the emissions are not up to standards you
may still want use the conversion for the purpose of listenin