CONAR RECEIVER MODIFICATIONS !!!
"....a face only a mother could love."
Standby Switch Mod
This mod replaces the CW-STBY-AM switch on the front panel.
If you have completed all the modifications so far, your CONAR receiver will function as promised. After serveral contacts, I have found the need to modify it further. Part of my style of operating CW is that I like to listen to my signal as I key the transmitter. This does three things for me:
(1) I know the transmitter is working.
(2) I can send better because I am hearing myself send
(3) I am sure I am tuned to the proper place on the receiver.
Most CW transmitters off a "spot" position that allows you to tune your reciever to the correct frequency. Others will tell you, CW keyers do produce sounds so you can hear yourself send and a SWR meter proves the transmitter is working.
Still, I prefer getting this audio feedback directly from the receiver and I think you might too.
In order for this to work right, several things will have to happen in the receiver when the switch is thrown in STBY position.
(1) First the BFO must be turned ON in the Standby position.
(2) You must reduce the RF gain control to minimum so the transmitter does not overload the receiver.
(3) The Diode dectector D2 sensitivity must be adjust so audio is at a normal listening level.
(4) The Antenna Relay must be keyed so the relay can switch the transmitter to the antenna.
These four things must occur simultaneously. The present standby ONE pole-3 position switch can only do one of these functions so it MUST BE replaced. I selected a 4 Pole-3 Position Switch for $1.25. This particular switch is about the same size as the switch that it replaced. Here is the basic switch shown in the STBY position viewed from the rear:
Of all the controls on the receiver, this one will be the one used most often. The switch is a plastic low voltage type but it has a nice "feel and snap" to it when you turn it. After several hundred QSO's, I have had no problems with it at all. Here is a picture of the switch on the right side of the metal VOL control pot. You can see the 120 VAC power swtich mounted behind the Vol pot.
As you can see things are a bit tight. Part of the problem is that the terminal strip supporting the 120 VAC Neon indicator is at the bottom and one edge comes real close to the switch. I had to bend some tabs around so it wouldn't touch. It looks like one big pile up right at the resistor lead but this was the closest and best angle I could get my camera into. Trust me, they don't touch!
If your careful, you should not have any problems. The following sections go over each of the 4 poles and it's functions. I recommend as you do each section, double check your wiring and then turn on the receiver and test it to make sure it works properly.
The only equipment you will need will be a CONAR transmitter, your favorite XTAL, a dummy load (such as a 25 watt lamp bulb) and of course, a straight key.
OK? Take a deep breath and let's get started!
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