28-09-2023, 09:58 AM
Another issue with early PLL/synth based models was phase noise on transmit or receive. Earlier models used a stable VFO at about 5MHz with about 500KHz range and a crystal per band. Later models used a DDS and only used the PLL for larger steps, giving lower noise synthesis, certainly FT817 and FT817ND and possibly FT857.
Still easy to replace the finals on all the later FT101 series, the 6146 pair in parallel driven by a 12BY7A . The digital display can fail on the later ones, but it's just a custom counter so though the IC is unobtainable, the function has been replaced by a PIC.
The FT847 was 1998 to 2005.
The last FT101ZD was about 1985. The FT102 is best avoided as it uses a large number of unsealed relays which often need replaced (1982-1984).
I think for a S/H rig I'd go for ones without a synth (1970s to mid 1980s) or one from the late 1990s onward.
The mid 1980s to mid 1990s rigs with synth (earliest ones bad), no DDS, cpu, and transistor finals (prone to fail and some hard to find) are maybe best avoided. The FT767GX was 1982-1984.
I've tested some 1980s Racal military sets that used MPUs & PLL and very prone to blowing finals and also very noisy. The MPU and synth was also used for frequency hopping scrambling, an option PCB on some models. Frequency (and code) entry via 10 way switch per digit.
Earlier 2m rigs (from 1980s) used the same design as 40 channel CBs, sometimes the same the CMOS synth at about 3MHz and crystal plus mixer to VFO 10.7 MHz below RF. The channel switch driving synth via diode matrix. The 1970s ones usually used a pair of crystals per channel and quite like VHF Marine radios of 1970s.
HF Summary, 1970s to 1980s (avoid military & commercial) without synth/PLL (SSB steps too small without DDS), OR post 1997.
VHF/UHF: After 1990s.
I still have my FT817ND bought new in 2006 (with already extended 40m).
I've had 2x FT101ZDs, a MkII and a MkIII. Replaced the perfect MkIII with an FTdx10 last September, though it's still in the family (in storage).
I've had other sets I've got rid off and transverters for 2m & 70cm for the FT101ZD. I bought some ex-PMR rigs for 70MHz/4m but never got them working. Needed crystals changed. The FTdx10 works well on 6m and 4m. I have add-on 20W PAs for 2m & 70cm and yagis for the FT817ND. Putting the PAs near the aerial end of the feed boosts TX power.
It looks like a simple TX only transverter with a 20MHz crystal/ref osc, mixer, PA & filter would add the extra 30MHz to 50MHz frequencies allowed in Ireland to the FTdx10 as it receives up to I think 75MHz. The 30MHz to 50MHz filter will help receive as the built in filtering is only good up to 30MHz and for 6m/50MHz. Not sure what it does on 70MHz/4m as the ATU (internal or external FC40) only does to 50MHz.
I have the Elecraft ATU for FT817 and also the FC40 for the FTdx10. The big advantage over a manual ATU, really a match box not a tuner, (which isn't hard to make ) is putting the box at or near the aerial as you can't match if the feed is getting more than about 1/5th Wavelength (ideally less). With a long feed you are really simply matching the feed cable as an aerial if the aerial is bad match. I've a high power coax relay for the output of the FC40 to swap between a vertical and long wire. The vertical was "tuned" (with some difficulty using a VNA) to give a good match on 70MHz/4m, which makes it nearly impossible to match on 50MHz/6m as it's too close to a half-wave. The FC40 nor inbuilt FTdx10 ATU won't match a half-wave. A base matching coil is what is used normally, but then the vertical only works on 6m! An alternate solution is a particular length of coax between ATU and whip. Then on bypass and 70MHz, the coax isn't significant. Also not on 80m to 10m (vertical too short for ATU on 160m without a massive series coil), but on 6m the coax between tuner and 1/2 wave can "match" it if it's the right length (it's not really matching it, but the ATU thinks it is as SWR will seem OK.
Still easy to replace the finals on all the later FT101 series, the 6146 pair in parallel driven by a 12BY7A . The digital display can fail on the later ones, but it's just a custom counter so though the IC is unobtainable, the function has been replaced by a PIC.
The FT847 was 1998 to 2005.
The last FT101ZD was about 1985. The FT102 is best avoided as it uses a large number of unsealed relays which often need replaced (1982-1984).
I think for a S/H rig I'd go for ones without a synth (1970s to mid 1980s) or one from the late 1990s onward.
The mid 1980s to mid 1990s rigs with synth (earliest ones bad), no DDS, cpu, and transistor finals (prone to fail and some hard to find) are maybe best avoided. The FT767GX was 1982-1984.
I've tested some 1980s Racal military sets that used MPUs & PLL and very prone to blowing finals and also very noisy. The MPU and synth was also used for frequency hopping scrambling, an option PCB on some models. Frequency (and code) entry via 10 way switch per digit.
Earlier 2m rigs (from 1980s) used the same design as 40 channel CBs, sometimes the same the CMOS synth at about 3MHz and crystal plus mixer to VFO 10.7 MHz below RF. The channel switch driving synth via diode matrix. The 1970s ones usually used a pair of crystals per channel and quite like VHF Marine radios of 1970s.
HF Summary, 1970s to 1980s (avoid military & commercial) without synth/PLL (SSB steps too small without DDS), OR post 1997.
VHF/UHF: After 1990s.
I still have my FT817ND bought new in 2006 (with already extended 40m).
I've had 2x FT101ZDs, a MkII and a MkIII. Replaced the perfect MkIII with an FTdx10 last September, though it's still in the family (in storage).
I've had other sets I've got rid off and transverters for 2m & 70cm for the FT101ZD. I bought some ex-PMR rigs for 70MHz/4m but never got them working. Needed crystals changed. The FTdx10 works well on 6m and 4m. I have add-on 20W PAs for 2m & 70cm and yagis for the FT817ND. Putting the PAs near the aerial end of the feed boosts TX power.
It looks like a simple TX only transverter with a 20MHz crystal/ref osc, mixer, PA & filter would add the extra 30MHz to 50MHz frequencies allowed in Ireland to the FTdx10 as it receives up to I think 75MHz. The 30MHz to 50MHz filter will help receive as the built in filtering is only good up to 30MHz and for 6m/50MHz. Not sure what it does on 70MHz/4m as the ATU (internal or external FC40) only does to 50MHz.
I have the Elecraft ATU for FT817 and also the FC40 for the FTdx10. The big advantage over a manual ATU, really a match box not a tuner, (which isn't hard to make ) is putting the box at or near the aerial as you can't match if the feed is getting more than about 1/5th Wavelength (ideally less). With a long feed you are really simply matching the feed cable as an aerial if the aerial is bad match. I've a high power coax relay for the output of the FC40 to swap between a vertical and long wire. The vertical was "tuned" (with some difficulty using a VNA) to give a good match on 70MHz/4m, which makes it nearly impossible to match on 50MHz/6m as it's too close to a half-wave. The FC40 nor inbuilt FTdx10 ATU won't match a half-wave. A base matching coil is what is used normally, but then the vertical only works on 6m! An alternate solution is a particular length of coax between ATU and whip. Then on bypass and 70MHz, the coax isn't significant. Also not on 80m to 10m (vertical too short for ATU on 160m without a massive series coil), but on 6m the coax between tuner and 1/2 wave can "match" it if it's the right length (it's not really matching it, but the ATU thinks it is as SWR will seem OK.
