Glad you went over to TUBES, the LDMOS was a nice TRIAL Run, you stood behind your work with me and even gave ne a full refund after I was experiencing a lot of imd and harmonics with the LDMOS as well. It seems the LDMOs is hyped up to do so much power, yet it only handles clean power about half of its rated power.
@@DAVE_WHITE LDMOS has been discontinued at the beginning of the year. Being a very “Dirty” transistor is not the sole reason though. The reliability of these devices is worse the HG pills. Some NXP pill would blow up in under 10 min and some after a month with perfect running conditions. Running it at half power does make it cleaner however sometimes the transistor will just quit for no reason and no explanation. Tubes 100% now. With LDMOS in the trash.
Super awesome to see a 2-tone IMD test for LDMOS, thank you for sharing! I tried connecting 2 separate pallets with ART2K0’s (Ampleon) together using a 1:2 ferrite combiner like you show in this video, and I measured -20 dB of 3rd order IMD using 2-tone audio test at 2kw PEP which agrees closely with your results. I totally agree with you: -20 dB is not a good IMD result and will definitely cause some unwanted audio splatter, especially with SSB modes. But then I tried connecting 2 ART2K0’s in parallel on a single, unified pallet just like the ham radio guys do (no combiner is used because drains of FETs directly connect together electrically using a 9:1 transmission line transformer). IMD was much better, -33 dB for 3rd order IMD and -42 dB for 5th order IMD with 2-tone test using 2kw PEP for pOut. Connecting the drains together electrically in parallel vs. using a 1:2 RF combiner was a big improvement in IMD that I did not expect, but glad I tried it. The only downside is the higher cost of buying a second FET which is an extra $226 for ART2K0. The extra cost might be worth it if a super clean signal is needed, especially for SSB customers.
So with 2 devices you are basically operating one device at half power. And thats what my test was showing, when you get closer to 1kw PEP per device the IMD looks alot better. 2kw out of a single device is gonna be terrible.
Nice testing. I did notice that LDMOS does have some IMD at full ratings. From what testing I have done dropping to 50% of rating cleans them up a bunch. Tubes when biased correct are buy far cleaner on SSB. Other FETS like IRF520 get quite dirty at power ratings. When you go back to BJT like 2SC2290 they pretty clean at rating's bias and tunes correctly. Something with FET transistors on SSB. now go to AM/FM/CW they much better . I did notice running LDMOS at 50% power on SSB they run quite cool . 73
You pretty much summed up my video in your comment. Thats exactly what I have found. To get 30 or more db of 3rd suppression you have to get to 50% of rated power. I am gonna do a 2sc2879C test here in a bit and see how that performs. Thanks for your input.
I would say absolutely unless you turn the power way down. To be completely fair I am using a cheap Chinese power supply since there are very limited 65v power supplies. And there is a chance that partially its caused by the switching power supply voltage ripple. But I wasnt impressed by any LDMOS performance when it comes to signal quality, my design still outperforms alot of others but i am not impressed with the results. Now my 3cx3000 did fantastic if you watch a video from a few weeks ago.
FM is a constant wave basically CW and its totally fine. Third harmonic is more the 55dB down. AM has similar flat toping as well. But SSB is by far the best test for any amplifier especially designed to run on SSB. after about 1200W PEP signal starts to degrade and after about 1500W it really degrades. Most people buy these to run 2Kw.
@@NeedleBender785 So, it consistently outputs 2.0 KW on FM. I'm from Europe, where we mostly use FM or SSB. On FM, you could reduce the bias by a quarter or even run it entirely in Class C mode; it shouldn't make much difference. As a driver, I have a Hermes 3 SDR transceiver that puts out about 10W.
@@fnordist On FM i wouldnt run this device above 1kw for an extended period of time. The ammount of heat it generates is huge. I would say 1kw is the most you can get and it is very clean with very minimal bias probably class B.
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Glad you went over to TUBES, the LDMOS was a nice TRIAL Run, you stood behind your work with me and even gave ne a full refund after I was experiencing a lot of imd and harmonics with the LDMOS as well. It seems the LDMOs is hyped up to do so much power, yet it only handles clean power about half of its rated power.
@@DAVE_WHITE LDMOS has been discontinued at the beginning of the year. Being a very “Dirty” transistor is not the sole reason though. The reliability of these devices is worse the HG pills. Some NXP pill would blow up in under 10 min and some after a month with perfect running conditions. Running it at half power does make it cleaner however sometimes the transistor will just quit for no reason and no explanation. Tubes 100% now. With LDMOS in the trash.
@@NeedleBender785 Awesome but an expensive lesson for all. Glad you are still doing good work!!!
I’m late getting to the video ,, great work Tony !!
Super awesome to see a 2-tone IMD test for LDMOS, thank you for sharing! I tried connecting 2 separate pallets with ART2K0’s (Ampleon) together using a 1:2 ferrite combiner like you show in this video, and I measured -20 dB of 3rd order IMD using 2-tone audio test at 2kw PEP which agrees closely with your results. I totally agree with you: -20 dB is not a good IMD result and will definitely cause some unwanted audio splatter, especially with SSB modes. But then I tried connecting 2 ART2K0’s in parallel on a single, unified pallet just like the ham radio guys do (no combiner is used because drains of FETs directly connect together electrically using a 9:1 transmission line transformer). IMD was much better, -33 dB for 3rd order IMD and -42 dB for 5th order IMD with 2-tone test using 2kw PEP for pOut. Connecting the drains together electrically in parallel vs. using a 1:2 RF combiner was a big improvement in IMD that I did not expect, but glad I tried it. The only downside is the higher cost of buying a second FET which is an extra $226 for ART2K0. The extra cost might be worth it if a super clean signal is needed, especially for SSB customers.
So with 2 devices you are basically operating one device at half power. And thats what my test was showing, when you get closer to 1kw PEP per device the IMD looks alot better. 2kw out of a single device is gonna be terrible.
Nice testing. I did notice that LDMOS does have some IMD at full ratings. From what testing I have done dropping to 50% of rating cleans them up a bunch. Tubes when biased correct are buy far cleaner on SSB. Other FETS like IRF520 get quite dirty at power ratings. When you go back to BJT like 2SC2290 they pretty clean at rating's bias and tunes correctly. Something with FET transistors on SSB. now go to AM/FM/CW they much better . I did notice running LDMOS at 50% power on SSB they run quite cool . 73
You pretty much summed up my video in your comment. Thats exactly what I have found. To get 30 or more db of 3rd suppression you have to get to 50% of rated power. I am gonna do a 2sc2879C test here in a bit and see how that performs. Thanks for your input.
Pretty cool, I can't wait
Thanks!!!
Very cool. What do you use for your rf sampler that feeds your scope and spec-anny?
5000kw Bird RF Sampler with a built in attenuator.
Interesting, do you think the results are typical for that type of ldmos transistor?..
Thanks for sharing....73
I would say absolutely unless you turn the power way down. To be completely fair I am using a cheap Chinese power supply since there are very limited 65v power supplies. And there is a chance that partially its caused by the switching power supply voltage ripple. But I wasnt impressed by any LDMOS performance when it comes to signal quality, my design still outperforms alot of others but i am not impressed with the results. Now my 3cx3000 did fantastic if you watch a video from a few weeks ago.
@@NeedleBender785 yes absolutely -34db awesome
Look forward to seeing more in the future
When does this LDMOS start compressing? Have you tested it on FM yet?
FM is a constant wave basically CW and its totally fine. Third harmonic is more the 55dB down. AM has similar flat toping as well. But SSB is by far the best test for any amplifier especially designed to run on SSB. after about 1200W PEP signal starts to degrade and after about 1500W it really degrades. Most people buy these to run 2Kw.
@@NeedleBender785 So, it consistently outputs 2.0 KW on FM. I'm from Europe, where we mostly use FM or SSB. On FM, you could reduce the bias by a quarter or even run it entirely in Class C mode; it shouldn't make much difference. As a driver, I have a Hermes 3 SDR transceiver that puts out about 10W.
@@fnordist On FM i wouldnt run this device above 1kw for an extended period of time. The ammount of heat it generates is huge. I would say 1kw is the most you can get and it is very clean with very minimal bias probably class B.