Modifying the Ferrite Rod Antenna for the HOT ROD Radio
Once the case is opened and you have carefully removed the circuit board (see previous
pages), and have wired in the DFD, got it tweeked for accurate readout, you will have
undoubtedly have had some choice words for the tiny, thin wires that are connected to the
rod antenna. Well, they have to go, so now is the time to make a plan. Here's mine:
1. Pry the back cover off the SR-III's handle. It's cemented in place, but with judicious use of a thin-blade
screwdriver you can pry up one end and work it off from there.
2. The entire inside of the handle is not hollow - it is filled with about a dozen transverse stiffiner ribs. Cut them all
out. I used a pair of diagonal cutters and needle nose pliers. Cut the little buggers as close to the sides as
possible. Stick a small steel burr or similar grinding bit into your Dremel (hobby-hand grinder) and grind the
remaining rib pieces smooth to the sides of the handle. ALL THIS SOUNDS LIKE A LOT OF WORK, BUT IT
REALLY ISN'T. I DID THE WHOLE PROCESS IN 30 MINUTES. Just work at your own pace and don't grind through
the handle's wall. Don't do this part of the job because you have to do it - do it because you want to do it. Don't
hurry - enjoy the experience - it's the best gift you can give your technical ego (satisfaction).
3. BEFORE you cut the wires from the radio to the antenna rod, MARK THEM! There are 6 wires,but you only
need to worry about 4 of them. Two are for the oscillator winding and 2 are for the tuning section. Looking at the
PC board, right side up, you can identify the wires as: left-top, left-bottom, right-top, right-bottom -- easy, huh? I
wrote the letters "LT, LB, RT, RB on small strips of masking tape (see closeup below), and attached the tape to
the antenna wires VERY CLOSE to the rod ... not toward the radio end! The last 2 wires go to the external
antenna winding and really don't need any markings since they are so obvious. Now, go ahead and unsolder or
cut the wires free from the radio.
4. GENTLY place the rod into the hollowed out handle. Note how much room you have at each end -- not too
much. Center it so that the space on each end is equal and check with your choice of connector to be sure it will
fit. I elected to use chassis mount RCA phono connectors, but you decide what you want to do. I don't recommend
hard wiring to the thin wires - they are just fragile and really need some strain relief. I drilled two 5/16" holes
(.312") dead center on the first rib at each end (see photo). This is about the only way it's going to work.
5. The external antenna connection is very important for this radio, and I decided there is only one way to fit a
decent RF connector for my version. At the end of the rod where the external coils is, I drilled a 3/8" (.375") hole
VERY CLOSE to to RCA socket, but on the opposite side. If you make careful measurements, you'll see that it's all
Left: How I centered the RCA jacks
on the first rib groove in order to
clear the ferrite rod inside. Right:
The addition od an F-connector
adjacent to the RCA connector.
Solder carefully and don't burn the
plastic. Dress the thin wires neatly
and secure with bits of tape.
Below: Note the wire routing and
the little square labels which define
each wire. NOTE, to keep proper
polarity, I made LT and RT the
coax centers and LB and RB the
shields. The cables back to the
circuit board are about 12" of
RG-174 mini-coax. For added
safety, you can see little bits of
insulating paper between the
Finished, with cover in place using 6 x 23 screws. Next step is the brackets for the back of the new metal radio
chassis. And YES, you'll be able to use the handle as a HANDLE.
To obviate the loopstick antenna from receiving signals when an external antenna is employed, this assembly will
fold down into a shielded compartment
The antenna rod assembly wired and connected to the radio. Note the "F" fitting with coax attached. This will
connect to the antenna selector control on the front panel.