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6_meter_conversion_tait_t2020 [2018/09/13 23:44] (current)
vk3smb created
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 +While this conversion is easier than the [[6 Metre Conversion (PRM80)]], the same principals apply. ​ There is still Software mods, VCO mods (maybe), Filter changes, Receiver changes and in particular TX filter mods.
 +Download http://​​tait/​6metres.dat and load it into the 2020 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 enamelled copper wire for all coils except L327.
 +  * 0.95mm enamelled copper wire for L327.
 +==Receiver modifications==
 +Change the following components:
 +  * C342 - add 39pF
 +  * L320 - replace with 5.5 turns @ 5mm Dia.
 +  * L101 - replace with 7.5 turns @ 6mm Dia.
 +===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:
 +  * L327 - 1.5 turns @ 4mm Dia. (Using the 0.95mm wire)
 +  * L316 - 3.5 turns @ 6mm Dia.
 +  * L301 - 5.5 turns @ 4mm Dia.
 +  * L302 - 4.5 turns @ 5mm Dia.
 +  * L304 - 2.5 turns @ 4mm Dia.
 +  * L307 - 4.5 turns @ 3mm Dia. (Raised above PCB by 1mm).
 +  * L325 - 2.5 turns @ 4mm Dia. (Raised above PCB by 1mm).
 +  * L313 - Spread the turns to maximise output power.
 +You should now have  > 25W TX power at around 6A, and a sensitivity ~-125dBm
 +===Real life===
 +I have modified one of these, and it works great. ​ however the unit I modified was a narrow band model, 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.
 +I'm not going to take credit for this mod..... ​ I have had it written down now for about 7 years and not told anyone.
6_meter_conversion_tait_t2020.txt ยท Last modified: 2018/09/13 23:44 by vk3smb