I finally got around to messing with this leading character truncation problem
Wednesday, I swapped out the problematic FT-1000D with another FT-1000D. This
appeared to cure the problem until I noticed that the autotuner was activated
FT-1000D. When I turned off the autotuner, the problem re-appeared on the
FT-1000D. This was despite a low VSWR reading between the AL-82 and the
When I reactivated the autotuner, the rise time appeared normal. I then start
with the drive to the AL-82, and noticed that at some point (~1400W output and
mA of grid current), the truncation problem re-occured (this time with the
activated). When I backed down the drive a little (~200 mA grid current)
seemed okay again. Curious, I swapped out the FT-1000's again, and was able to
reproduce the exact same behavior on the first FT-1000D (e.g. no truncation with
autotuner on, and moderate PA drive).
Any thoughts guys?
73 de Mike, W4EF..............................
----- Original Message -----
From: "Bert Barry" <email@example.com>
Cc: "Michael Tope" <W4EF@dellroy.com>; "AMPS" <firstname.lastname@example.org>
Sent: Sunday, March 25, 2001 1:25 PM
Subject: Re: [AMPS] Problem with Ameritron AL-82
> That's a good point Tom, but I suggest cleaning both the switch pins and the
> pins as well as the swich contacts. By a great coincidence, shortly after I
> my note, my problem occurred again, after being OK for several months. (Last
> time I
> simply reflowed the relay pins, and that worked, until now). This time I
> the resistance at the phono jack with key down and found it varied all over
> place, from a couple of ohms, up to 50 or 60, then back down to 15 to 20, as I
> jiggled the phono plug. I then took the bottom off and as soon as I touched
> relay (not the switch), the resistance dropped to less than an ohm. I then
> the solder off the relay pins, resoldered, and resistance seems to be less
> than an
> ohm, and doesn't vary while jiggling the phono plug. But in view of your
> before putting the rig back together I'll clean and resolder the switch pins,
> spray contact cleaner on the switch contacts. But my feeling is that it's
> the relay
> pins that develop high resistance or open circuit from the vibration of relay
> The only problem with this approach is that I'll never be sure which was the
> Mike, let us know how you make out, and your opinion.
> Bert, VE3QAA
> Tom Rauch wrote:
> > > I had exactly the same problem with my Alpha 87 driven by an FT-1000D.
> > > The problem was not the amplifier - it was a fault in the wiring to
> > > the "tx-gnd" phono jack on the back of the FT-1000. Fortunately, at
> > > least in my case, the problem was NOT in the FT-1000 tx-gnd relay,
> > > which would have been a pig to replace.
> > This makes me wonder.
> > My FT1000D has dropped the switch lead a three times now, and
> > while it was on the way out it did something similar to what Mike
> > described except on many occasions it would NEVER close the
> > amp relay.
> > The first time I just barely touched the relay switch near the jack
> > and it cured the problem. The second time (about a year later) I
> > resoldered the connections on the switch, and it was OK for a
> > week.
> > The third time I cleaned the switch contacts, and it has been OK
> > for almost a year now.
> > I wonder if the switches aren't the problem, since mine would
> > straighten out just by touching it or anything around it??
> > 73, Tom W8JI
> > W8JI@contesting.com
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