I am looking for ideas or suggestions on how PureSignal performance can be improved. The factory spec for the EP4CE 7000 DLE Mk2 is -68 IMD3 on 20m @ 100w, but I have never been able to do better than maybe -50 to -55 IMD3, with either the inbuilt coupler or an external coupler.
Following are measurements on 20m, 14.1 MHz at 100w into a 50 ohm load. The radio is using the inbuilt coupler, additionally the spectrum analyzer is fed with a -55 db sampler placed between the radio and the 50 ohm load, with an additional 20dB of attenuation to ensure we are seeing the real signal and not intermodulation generated in the spectrum analyzer.
I was curious about the signal feeding the 100w PA, so for reference here is the output of the Orion Mk2 card with the PA disabled, both PS OFF and PS ON.
Would this be a defect? What do you measure from your 7000 DLE MK2, and how can it be made better?
Suggestions to improve PS operation on 7k DLE Mk2.5?
Re: Suggestions to improve PS operation on 7k DLE Mk2.5?
IMHO the "factory spec's" are rather optimistic, to say the least.
-50dBc is typically what I see out of my modified 100D and my 8000DLE, with or without an external amplifier.
People used to be seriously into tweaking the bias of the internal amp in the 100D and 200D days, and working on reducing both internal and external crosstalk with better cabling and external couplers and switches, and some reported getting to -60dBc or thereabouts.
-50dBc is typically what I see out of my modified 100D and my 8000DLE, with or without an external amplifier.
People used to be seriously into tweaking the bias of the internal amp in the 100D and 200D days, and working on reducing both internal and external crosstalk with better cabling and external couplers and switches, and some reported getting to -60dBc or thereabouts.
Re: Suggestions to improve PS operation on 7k DLE Mk2.5?
w-u-2-o wrote:IMHO the "factory spec's" are rather optimistic, to say the least.
-50dBc is typically what I see out of my modified 100D and my 8000DLE, with or without an external amplifier.
People used to be seriously into tweaking the bias of the internal amp in the 100D and 200D days, and working on reducing both internal and external crosstalk with better cabling and external couplers and switches, and some reported getting to -60dBc or thereabouts.
Thanks Scott, as always. Glad to hear the measurements are in the ballpark.
I have not been able to dredge up such information discussing those topics, but I would like to read them if you can point me in the right direction. Anyways since there is currently no functioning current sensor on the EP4CE 7000's so it would be difficult to set bias current until I get more creative, so I guess that's academic anyways.
Re: Suggestions to improve PS operation on 7k DLE Mk2.5?
Gosh, that stuff from those days is unfortunately lost to the sands of time. There was much discussion on the old Yahoo Group. But when Yahoo shut the groups down there was no effective way to migrate all that, although I was able to migrate files and photos, which you can find in the forum here.
And, gosh again , when folks were tweaking biases they just used an ammeter on the main power supply. First they turned the bias controls all the way down, took a baseline reading, then started increasing each bias control in turn and looking at the increase in overall current. One thing we found was that since the design is not thermally compensated the adjustment could only be an approximate one. If you tried too hard you just wound up chasing your tail. It would be the same on the 7000.
And, gosh again , when folks were tweaking biases they just used an ammeter on the main power supply. First they turned the bias controls all the way down, took a baseline reading, then started increasing each bias control in turn and looking at the increase in overall current. One thing we found was that since the design is not thermally compensated the adjustment could only be an approximate one. If you tried too hard you just wound up chasing your tail. It would be the same on the 7000.
Re: Suggestions to improve PS operation on 7k DLE Mk2.5?
If it helps, I have a PDF document with a suggested procedure for how to adjust the driver and PA bias that I wrote mostly so I wouldn't forget how I did it. The document explains the steps I used with my ANAN-100 back when it was new. After the adjustment it certainly was more linear when Pure Signal was not engaged but to be honest I did not notice much difference when Pure Signal was engaged.
73, Rob W1AEX
https://www.w1aex.com/archive/ANAN_Archive/ANAN_bias_adjustment_W1AEX.pdf
73, Rob W1AEX
https://www.w1aex.com/archive/ANAN_Archive/ANAN_bias_adjustment_W1AEX.pdf
"One thing I am certain of is that there is too much certainty in the world."
Re: Suggestions to improve PS operation on 7k DLE Mk2.5?
Thanks Rob, and Scott, for the info.
I measured the total draw in RX at 1.07 A, and when keyed with silence 3.4 A. I think that's pretty much in the ballpark, assuming 1A per device.
Do we know what the stock bias is meant to be on the recent 7000?
I measured the total draw in RX at 1.07 A, and when keyed with silence 3.4 A. I think that's pretty much in the ballpark, assuming 1A per device.
Do we know what the stock bias is meant to be on the recent 7000?