You do have to go back and forth to peak them up in my limited experience.? I use a spectrum analyzer to do mine because seeing the signal vs hearing it is a lot more accurate.? I would also check what filter set is in the radio.? If it's an early TR-4 with the soup can filters I would be suspicious of the filters.? How is the carrier oscillator alignment?? It needs to be recentered and T6/T13 adjusted if it has to be recentered after the first round.? And it should be centered before you begin.? I do that with the spectrum analyzer also.??
On Wednesday, May 14, 2025 at 02:56:50 PM CDT, Steve Wedge, W1ES/4 via groups.io <w1es@...> wrote:
Okay, I need a little help from the real engineers here.
When doind a TR-4 filter match adjustment, I invariably come up with having to redo the adjustment several times.? T6 and T13 appear to be at opposite ends of the filters.? I can see why you want to get the received strength the same by tuning the PTO to the one place where the signals on opposite sidebands have the same strength and I get using S3 as the signal before tweaking the transformers so that you're not overloading anything (overcoupling?)? Why does it seem to take 3-5 cycles of this?
The TR-4 I'm working on has a host of problems (and I'm about to set it aside for a couple of months, as the owner has told me to "take my time". and the filter match was way out of adjustment -- implying that someone else was "in there" and didn't do the procedure quite right.
Do these filter match transformer adjustments interact?? I am inclined to believe that they do.
What happens if the adjustment is off?? Simply reduced response on one sideband?
This TR-4 has had 4 bad tubes, plus bad finals, and an intermittent fault that comes as the rig warms up -- but -- the problem also disappears with the rig warmed up.??
Voltage checks on some of the tubes have revealed some voltage differences that I'd largely chalk up to old resistors.? They're in the ballpark.? It's too bad, because this set is about an 8.5 cosmetically...
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
