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- Seamless integration with WriteLog.
- Optically isolated Left and Right Morse CW and PTT outputs.
- Footswitch input.
- Reliable front panel Morse speed and Left/Right overides.
- One COM port does both CW and rig control.
Aside from the fact you can't get one, the MK-1100's biggest issue in the modern ham shack is its requirement for low latency on the PC COM port modem control lines. PC's with a motherboard COM port can be counted on to have adequate specifications for the MK-1100, but USB to Serial dongles generally do not.
Here are redesigns that resolve both those issues.
The MK-1103 and MK-1104 are the newest designs, stacked on the left, using SMD parts and 3D printed enclosures:
They are software compatible with all versions of WriteLog back to version 10.10 (minor exceptions detailed below) and pin-out compatible with the original MK-1100. The new parts are smaller, so you get a smaller footprint at your operating position. A complete parts list is provided below, including designs for 3D printed enclosures. Printed circuit layouts are published here in the format supported by http://expresspcb.com. The necessary firmware is also published here.
This design can be built in either of two variations: (a) the MK-1103 has the essential features for SO2R in the smallest package and (b) the MK-1104 adds the full implementation of all features and connectors of the original MK-1100. WriteLog accesses any of them with its same MK-1100 setting. The features in the MK-1104 omitted from the smaller MK-1103 device are:
- 25 pin D LPT outputs for both Left and Right radios with TTL levels for 4-bit band decoding, L/R radio indicator, CW and PTT.
- Stereo audio switching for Left and Right receivers to Headphones.
The MK-1103 and MK-1104 designs share the main printed circuit board implementing the features they have in common. The MK-1104 adds a second circuit board (named "Aux" on its silkscreen) with the LPT ports. The RX audio switching section needed in the MK-1104 is partitioned on the main board with a clearly marked series of holes. Use them to saw the full width board down to the MK-1103 smallest possible footprint. Each design fits into a custom 3D printed enclosure.
The MK-1103 and MK-1104 are highly compatible with the original MK-1100 with these minor differences.- USB-C connector to PC instead of RS-232 9 pin D.
- sidetone on audio sounder instead of coupling into headphone switching.
- the manual speed and L/R switch are on the front panel instead of on remote cable.
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MK-1100 required external 7.5-25V DC, accepting either polarity on center pin.
- the MK-1103 has no external power jack and instead is powered through USB
- MK-1104 requires 7.5-12V DC, positive on center pin, but accepts the same power connector as the MK-1100.
- The self test built into the MK-1101 through MK-1104 requires a different fixture than the MK-1100. A PCB layout for the newer test fixture is published here.
- The MK-1104 fits into a much smaller space than the MK-1100, and the MK-1103 is smaller still.
The MK-1103 and MK-1104 jacks have the same pinout as the original MK-1100, and, except for substituting the micro-USB for the 9 pin D, and the requirement for positive polarity on the 12VDC center pin, the instructions for connecting the MK-1101 through MK-1104 are identical to the instructions for the original model.
Parts lists and complete instructions for building both the MK-1103 and MK-1104.
MK-1103 and MK-1104 main board
MK-1104-only section of main board
MK-1103 and MK-1104 main board serial port diagnostic switch.
If you're going to build more than one of these keyers, this Test Fixture simplifies the checkout.
For reference, hare are photos of the older MK-1101 and MK-1102 designs in their aluminum Bud enclosures.
The MK1101 (back panel, before application of dry transfers) front left, MK1102 (front panel) back left, and original MK1100, right.
These updated devices duplicate the functionality of the MK-1100, plug into your PC using USB, and can be built in quantity one using parts readily available in 2018.
