05-10-2023, 05:58 AM
The ratings on most automatic ATU's are for SSB or CW duty cycle (50%) and then there is also the listening 50% of the time. Hence if there is a continous data transmission they may only be capable of something like 30% of what their "official" rating is.
I'm now into balanced tuners but I'm very fond of the Collins 180S-1 ATU for end fed - I'd one and sold it when I abandoned HAM radio. I actually have the parts for two - one for the lower end of the HF bands and another for 30 -10. For the 160 -80 - 40 I've got a NIB unused Hammarlund TCD-240-J instead of the vacuum Jennings capacitor. It's a dual 250pF 4.25kV and dates back to 1946! If the box only could tell the story where it has been all this time. For the 30 - 10 I've got a E F Johnson 150F20: a 160pF, 2kV to be used as the output shunt capacitor.
Also found three NOS 1kW , 2 kV 2 poles, 11 position ceramic switches. Price was too good to pass them up, they were the remnants of a business that has closed. Don't know yet what to do with them, might use one for switching the capacitor from input to the output in a balanced L-C ATU, have got 3 Le Pointe 10uH inductors, two NOS, one used and a Cardwell 10uH. That would give me also some interesting options like making a balanced L-C-L tuner. (the "Annecke")
I'm guarding my stash closely - these items are harder to find and the ones that I do find in good condition are often estate sales and have been closely guarded. Plenty of rubbish around that I will not touch with a bargepole.
Making antenna's and ATU's is about the only thing left for amateurs these days, the rigs themselves have become too complex to fix and even when capable of fixing one may not have the right software to adjust everything.
At the moment I'm investigating the best choke for the balanced ATU - only limited choices locally available both in size and in composition. I'll have to stack some toroids to get to a comfortable power level (want to be able to handle 400 - 500 Watts although I'm only using about 50 watts output).
73's
I'm now into balanced tuners but I'm very fond of the Collins 180S-1 ATU for end fed - I'd one and sold it when I abandoned HAM radio. I actually have the parts for two - one for the lower end of the HF bands and another for 30 -10. For the 160 -80 - 40 I've got a NIB unused Hammarlund TCD-240-J instead of the vacuum Jennings capacitor. It's a dual 250pF 4.25kV and dates back to 1946! If the box only could tell the story where it has been all this time. For the 30 - 10 I've got a E F Johnson 150F20: a 160pF, 2kV to be used as the output shunt capacitor.
Also found three NOS 1kW , 2 kV 2 poles, 11 position ceramic switches. Price was too good to pass them up, they were the remnants of a business that has closed. Don't know yet what to do with them, might use one for switching the capacitor from input to the output in a balanced L-C ATU, have got 3 Le Pointe 10uH inductors, two NOS, one used and a Cardwell 10uH. That would give me also some interesting options like making a balanced L-C-L tuner. (the "Annecke")
I'm guarding my stash closely - these items are harder to find and the ones that I do find in good condition are often estate sales and have been closely guarded. Plenty of rubbish around that I will not touch with a bargepole.
Making antenna's and ATU's is about the only thing left for amateurs these days, the rigs themselves have become too complex to fix and even when capable of fixing one may not have the right software to adjust everything.
At the moment I'm investigating the best choke for the balanced ATU - only limited choices locally available both in size and in composition. I'll have to stack some toroids to get to a comfortable power level (want to be able to handle 400 - 500 Watts although I'm only using about 50 watts output).
73's
