Re: Tuning a pi-Network Output
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I took the PA cage off because it had a concavity to it that bothered me since it made the top of the cage that much closer to the plate caps.? I then noticed the neutralization capacitor is fully open.? I don't know if that's necessarily a bad thing but I can't help but think it should have at least a little capacitance.? I'll find out when I get around to adjusting it.
73, Barry - N4BUQ
The neut procedure is but no mention is made of what happens on the lower bands.
Neutralisation is most important at the highest frequencies, I have been told for years.? Being a bit "off" on lower bands is supposedly less critical.
Then we have the 40m oscillations in the TR7, so I guess these items aren't cast in stone.??
For the purposes of the TR-4(any), I'm guessing that 40m neut isn't as important.? There isn't one setting that causes exact plate-dip-max-power-out coincidence on all bands.
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
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On Thursday, April 3rd, 2025 at 11:03 AM, Rob Sherwood via groups.io <rob@...> wrote:
Isn¡¯t this behavior discussed under neutralization in the manual? ?Rob, NC0B?
On Apr 3, 2025, at 8:19?AM, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Barry, I¡¯ve found with the TR-3/4 that they don¡¯t 100% neutralise on all bands ¡ª especially 40m but sometimes 20m as well. It is unavoidable and the modeling of it is way above my pay grade.?
I still neutralise on the highest 10m band available (newer rigs made the upper two 10m bands
Optional). If all you have is the low 10m band Xtal, run the PTO to 28.6 and neutralise only after checking for coincident dip And max Power out.?
I keep my TR¡¯s at the plate dip, as it¡¯s passing less current. Chances are, you may lose 10-20W output but that difference is probably not detectable at the other end.?
Also, be mindful of ¡°rogue¡± resonances when tuning the driver. Stick within the range shown by the alignment procedure: I.e., if the preset alignment is at 7, avoid any peaks that are at, say, 2.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Thu, Apr 3, 2025 at 09:53, n4buq < n4buq@...> wrote:
I don't think I've ever owned a power meter and now I have one in my MN-2000. Tuning up my TR-4, I notice that maximizing the output power doesn't necessarily coincide with the "dip" in plate current but, instead,
seems to occur on the "edge" of that dip. Is this normal?
From many, many years ago, with only a plate meter, I always adjusted with the dip at its minimum value but now I'm wondering if that wasn't yielding maximum power output. Furthermore, I presume that getting the dip first and then tweaking for maximum output
is the most efficient way to run. Is that correct? Is what I'm seeing normal? I presume so but after all these years, I'm beginning to wonder.
If it matters, I'm currently only tuning into a Drake dummy load.
Thanks,
Barry - N4BUQ
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