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The board has a pass-through trace if no relays are selected.? RF in and OUT.? As you select a single relay, it pulls the contacts off the jump trace and places the inductor in series.? The caps go to ground. Simple.
I was just testing the board into the amp. I understand that it will be different once installed and that Unun mess is removed.
I read online that you should use the .01 coupling cap when making your bench settings.?
I tried this and found no difference on any band.? ?There is a page online where a man shows how the coupling cap effects it with graphs. I think he had something else going on.?
Its very hard to believe the -50 figure.? That seems out of the range of reality.? ?I have measured dozens and dozens of amps here and most are -29 to -32 DB range using a radio that is -45? The only two amps that are better are my 4cx10000D, which is showing
-60DB down as good as the rig and my Collins 30S1 which shows in the -45 range.?
Remember, I was NOT using a Two-tone generator for my tests that I posted for the 8K. I was simply using a RTTY carrier with the Spec An loosely coupled.? ?
I was just trying to see if the board was in fact working on all bands and trying to see how much its going to lower harmonics as I tuned each band.
I also wanted to see if the inductors would heat with a 100W RTTY carrier through them. They dont.? They run cool and imagine how much air will be on the board near the tube socket.
Once I install the board, I can run a two-tone proper test and see how the overall amp performs.? It's dirty now. Real dirty.??
One thing I will circle back on is the adjustment of the LOAD side inductor in the 8k ultra.? ?Peter got me thinking.
The book shows how to align the big roller and the load side roller.? I was told by a man that worked for Henry on the 8k to adjust the load coil for max output.??
To do this you tune the amp on 20 meters,? Derail the chain and manually adjust the Load inductor for max output.? I did this with a tuning pulser and found 1000w!!! more output.? ?
I am now thinking of resetting it and testing the harmonics again to see if this throws off the network.??
Unfortunately, I was in the hospital over new year's and they found a herniated disk in my back, A growth on one disk and a problem in with my SI on left side.? I have been in massive pain and started physical therapy.? I don't think it's a good idea that I
pull that RF deck right now. I am going to have to wait a bit and get a friend over here to help me yank it!?
C
Clark, does the tuned input board have some sort of bypass mode ??? ? It would require one extra relay to pull that off.?
With relays wired correctly, only one relay is ever energized....(for whatever band it's on).? ?With no relays energized, the xcvr should see a wide open.? ?
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If the output of the tuned input board is feeding that back to back un-un mess, that could easily screw things up.? You might want to at least temp bypass the 3 x un-uns and the relay that switches the back to back un-uns to the single un-un. Then retweak
the Arco's.? If all is well, then remove the mess of un-uns + their relay.? Then feed the output of the tuned inputs....to the cathode..via the oem henry 4 x paralleled? .01uf coupling caps.?
A .01 uf coupling cap should not affect the tuning.? .01uf = 10,000 pf? =? 8.84 ohms of XL @ 1.8 mhz? = dick, non issue.? ?4 x .01uf caps in parallel = 40,000 pf =? 2.21 ohms of XC @ 1.8 mhz? = less than dick.?
Typ kw PI network on the output side is down 50 db for 2nd harmonic suppression.....and even more with a PI-L.? With the un-un mess bypassed / removed, you will probably see a big improvement.?
In the high gloss? Eimac catalog, they state IMD3 for the 3CX-3000A7? is -53dbc (-59db pep)...and that's at 5 kw pep out, using their 2 tone test.? ? It's one of the cleanest tubes in the entire catalog.?
Jim? ?VE7RF
