Ultra PicoKeyer
27 January 2017 (Firmware V2.2)
Page 7 of 21
probably want to find this peak so you can hear it with the case assembled. The default setting should be at this
audio peak.
Using headphones for sidetone
If you prefer, you can use a 3.5 mm stereo plug to connect an external device for sidetone. This will disconnect the
on-board speaker. The PIC processor chip used in the Ultra PicoKeyer can drive small ear buds or headphones
with 32 ohms or greater impedance. Low impedance phones will result in very low or no sidetone volume. For
larger speakers or lower impedance headphones, you’ll need to use and external amplifier. An inexpensive
amplified PC speaker may work well, or you can use this as an opportunity to build a low power audio amplifier.
An LM386 amplifier chip will work well for this, as well as many other types.
You will need to use a stereo plug for an external audio device. If you need to use a mono plug, you can cut the
PCB trace on the bottom of the board under the PHONES jack. It’s the trace that runs between the two outer-most
pads of the jack. This will work fine with mono headphones, and will give you sidetone in one ear with stereo
‘phones.
USE CAUTION when trying ear buds or headphones! Some ear buds or headphones may be uncomfortably loud,
or even loud enough to damage your hearing. NEVER use a headset or earbuds directly on or in your ears until you
know how loud the sidetone will be. If it’s too loud, you can try a smaller value capacitor in place of C3. You can
also connect an external variable resistor to use as a volume control.
Keying the transmitter
The PicoKeyer will key any solid state, tube or hybrid transmitter or transceivers that uses a keying voltage of
60 V
or less
, either positive or negative.
Your transmitter or transceiver may need either a mono or stereo cable. It depends on the rig; check your owner’s
manual for details for connecting a straight key to your transmitter. The PicoKeyer’s output acts like a straight key,
so you’ll use the method for connecting a straight key. Remember to disable the rig’s internal keyer, if it has one.
If you intend to use the PicoKeyer with a rig requiring grid-block or cathode keying voltages over 60 V, you will
need to use a separate high voltage keying adapter. The Universal Keying Adapter 3 available from NØXAS at
www.hamgadgets.com is optically isolated and will handle solid-state, grid-block or cathode keyed transmitters at
up to 400 V. Of course, you can always build your own!
Keying Modes (What’s Mode A, Mode B and Ultimatic??)
There have been a couple of different operating modes for iambic keying that have evolved over the years. Modes
A & B are simply a matter of when the keyer checks for input from the paddles. In iambic mode A, the keyer only
checks for paddle inputs after the end of each dot or dash. In iambic mode B, on the other hand, the keyer will
check for paddle input during each dot or dash.
In practice, this can mean that you get “extra” or “dropped” dots or dashes at the end of a character, depending on
how you send. If you find that the keyer often drops the last dot or dash in a character, or you often get an extra dot
or dash at the end of a character, try switching between modes A & B and see which one best suits you. I find that
Mode B worked best for me when using a single-lever paddle, while Mode A works best with a dual-lever paddle.
Ultimatic mode is a different way of handling iambic keying. In modes A & B, if the keyer sees both paddles
closed it will alternate sending dots and dashes. Ultimatic, on the other hand, will send dots or dashes
according to
the last paddle to be pressed
. For example, to send the letter P in mode A or B, you would close the dot paddle,
