Wayne Wright edited this page Mar 18, 2018 · 12 revisions

MK1101 and MK1102

The W5XD Multi-Keyer model MK-1100 has been out of production for many years, but several of its features are still not obsolete. These include:
  • 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.

MK1100-MK1101-MK1102.jpg

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.

MK1102-front.jpg

MK1102-back.jpg

With minor exceptions detailed below, they are software compatible with all versions of WriteLog back to version 10.10, 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 commercially manufactured enclosures, along with drilling templates for them. Printed circuit layouts are published here in the format supported by http://expresspcb.com. The necessary firmware is also published here.

This design has two variations that can be built. The MK-1101 has the essential features for SO2R in the smallest package. The MK-1102 adds the full implementation of all features and connectors of the original MK-1100. WriteLog accesses any of the three with its same MK-1100 setting. The features in the MK-1102 omitted from the smaller MK-1101 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-1101 and MK-1102 designs share the main printed circuit board implementing the features they have in common. The MK-1102 adds a second circuit board (called "Aux" on its silkscreen) with the LPT ports and headphone switching. Each design fits into a commercially manufactured Bud enclosure, the MK-1101 into a smaller model of the same series. The second board is connected to the main board by 8 conductor cable using RS-485 signalling, and requires a 12VDC supply. This division adds yet a third packaging option (not further documented here) to separate the two boards over a large distance should you design your own two enclosures. The MK-1102 design detailed here fits both boards into one enclosure.

Differences from MK-1100

While the MK-1101 and MK-1102 are highly compatible with the original MK-1100, there are a few design details that differ.
  • micro-USB connector to PC instead of RS-232 9 pin D.
  • sidetone on audio sounder instead of coupling into headphone switching.
  • manual speed and L/R switch on front panel instead of on remote cable.
  • the MK-1101 is powered through USB. MK-1102 requires 7.5-12V DC, positive on center pin. MK-1100 required external 7.5-25V DC, either polarity on center pin. The power jacks mate with the same connectors.
  • The self test built into the MK-1101 and MK-1102 requires a different fixture than the MK-1100. A PCB layout for a MK-1101 and MK-1102 test fixture is published here.
  • The MK-1102 fits into a much smaller space than the MK-1100, and the MK-1101 is smaller still.

Cabling and Operation

The MK-1101 and MK-1102 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 and MK-1102 are identical to the instructions for the original model.

Construction

Parts lists and complete instructions for building both the MK-1101 and MK-1102.

Schematics

MK-1101 and MK-1102 main board

MK-1102 aux board

Test Fixture

If you're going to build more than one of these, this Test Fixture simplifies the checkout.
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