Tait 2020 to 6 Meters mod

[Werthers]

Although the Tait T2020 is FM only, a Tait T2020 low band 68 MHz to 88 MHz transceiver can still be a fun project for conversion to 6 meters.

There was some software for this that you could download to get your Tait T2020 onto 50 MHz but it would seem like its no longer available. It may still be out there somewhere but I haven't searched extensively for it yet.

Some modifications need to be done also.

While this conversion is easier than the 6 Meter Conversion (PRM80), the same principals apply... VCO mods (maybe), Filter changes, Receiver changes and in particular TX filter mods.

Programming software. You need version 2.54 or higher. After loading the file, program it to the radio, however, DO NOT let the program do a check on the settings,or it will fail.

VCO Check

Check the voltage on the VCO control line during TX and RX. Make sure the voltage stays above 2VDC over the entire band.

Low pass filter

There needs to be capacitance added here. Component Changes: C339 - add 27p

Winding Coils

You need the following for the coils: 0.5mm enameled copper wire for all coils except L327. not needed of you putferrie beads in existing coils 0.95mm enameled copper wire for L327. not needed of you put ferrie beads in existing coils.

Receiver modifications

Change the following components: C342 - add 39pF A end of L323 near antenna connector. L320 - replace with 5.5 turns @ 5mm Dia. Or add ferrite bead L101 - replace with 7.5 turns @ 6mm Dia. Or add ferrite bead.

Receiver re-alignment

Re-align the 3 RX front end coils. If the front end does not come good after even with the slugs well down into the coils, add a 10Kohm resistor across C116 to reduce the voltage applied to the varicap diodes. You need to see around 1VDC. Repeat the alignment.

Transmitter modifications

Replace the following coils:
You Can put ferrite beads in the existing coils to get them to tune down to 50 MHz
L318 Ferrite bead only.
L327 - 1.5 turns @ 4mm Dia. (Using the 0.95mm wire) ferrite bead only.
L316 - 3.5 turns @ 6mm Dia. ferrite bead only.
L301 - 5.5 turns @ 4mm Dia. ferrite bead only.
L302 - 4.5 turns @ 5mm Dia. Not needed.
L304 - 2.5 turns @ 4mm Dia. . Not needed.
L307 - 4.5 turns @ 3mm Dia. (Raised above PCB by 1mm). . Not needed.
L325 - 2.5 turns @ 4mm Dia. (Raised above PCB by 1mm). . Not needed.
L313 - Spread the turns to maximise output power. . Not needed.
L310 ferrite bead only.

The Tait T2020 should now have > 25W TX power at around 6A, and a sensitivity ~-125dBm

[Werthers]

Also just to add Taits are narrow band which means all the old school operators with units that deviate almost to 6khz or are off frequency chopped badly. The PRM80 is not as sensitive to this as the T2020, as their front ends are substantially wider... even on the narrow band model.