Okay guys, here it is, I finally got the time to dig into the amp.
I really couldn't "see" anything wrong with the grid resistors or
capacitors. One of the 33 ohm grid resistors measured 32 ohms and the
other, 34 ohms. While I couldn't measure the capacitance of the capacitors,
they both showed the characteristic behavior of deflecting an ohm meter and
decaying as they charge when you reverse the ohm meter leads, etc. (It's
hard to describe in words, but you all probably know what I mean.)
Well, I didn't see anything to convince me they were bad, but what the
hey -- I replaced the 1 watt resistors with 2 watters, and the grid
capacitors -- I didn't have any 220 pF, so I used 330s -- should be close
enough for now?
Also, since she was opened up, I went ahead and replaced the 2 decoupling
caps on the bias line, even though there was no indication physically or
electrically that there was anything wrong with them. But hey, for a few
cents worth of parts, it was worth a try.
Well, this made no difference.
Now what I DID see, is a slight discoloration of the Plate RF Choke. About
midway, covering maybe 5 turns, about an eighth of the circumference. The
choke still ohms out at about 3 ohms and the Plate Voltage meter sets dead
on 2400 V. I don't know if this is new, or if it was already there when I
bought the amp a couple years ago.
I DID discover, while playing with the variable bias resistor, that I had
adjusted it the wrong way when I first started having trouble. Moving the
tap to the other end got the bias up to oh, I'd call it 78 mA (I'm
interpolating between the marks here) vs. the recommended 90.
So I can now drive the current to about 340 mA and the power output is up to
about 300 watts, dead key (with voltage droop) and peak with fast dits of
about 500 watts.
BTW, although I haven't tried it on 10 or 15 meters, it behaves the same way
on 20, 40, and 80.
What do you guys now think?
Does this sound like soft tubes?
This is the first amplifier I have ever messed with, at least in a
troubleshooting way. So I don't have a feel for what I am seeing. Is it time
to try a new set of tubes?
Is the discoloration of the plate RFC a problem?
Your thoughts are appreciated.
Rick, WD8JJA.
----- Original Message -----
From: "Peter Frenning, OZ1PIF" <oz1pif@get2net.dk>
To: "R_Davis" <WD8JJA@arrl.net>; "H & W Electronics"
<info@handwelectronics.com>; <amps@contesting.com>
Sent: Tuesday, October 28, 2003 3:39 AM
Subject: Re: [Amps] FL-2100F/B
> I can't comment specifically on the "F" version, I have never seen it or
the
> documentation.
> I wondered about the same thing Rick, but can only report my findings. As
> stated by R.Measures, it probably was the end result of some major glitch
> (thinking back, I did have one - while tuning up on 10m, a BIG bang
ocurred
> causing my XYL to come running from the other end of the house! and a
split
> anode on one of the tubes (that was the end of my first set), as reported
I
> never got the second set to work satisfactorily).
> The reason for the two decoupling caps, is probably poor RF
characteristics
> of the electrolytic cap (remember that the design is more than 30 years
> old!)
>
> Vy 73 de OZ1PIF, Peter
>
> ********** OZ1PIF **************
> email: oz1pif(no-spam-filler)@get2net.dk
> http://hjem.get2net.dk/oz1pif
> Ph. +45 4619 3239
> Snailmail:
> Peter Frenning
> Ternevej 23
> DK-4130 Viby Sj.
> Denmark
> ***********************************
> ----- Original Message -----
> From: "R_Davis" <WD8JJA@arrl.net>
> To: "H & W Electronics" <info@handwelectronics.com>;
> <Fox_Tango@mailman.qth.net>; <amps@contesting.com>
> Sent: Tuesday, October 28, 2003 2:51 AM
> Subject: Re: [Amps] FL-2100F/B
>
>
> > Very interesting, Peter,
> >
> > Actually, the question was proposed by "H & W Electronics" on another
> > reflector; I have a 2100B with the similar symptoms, while he asked
about
> > the 2100F.
> >
> > The 2100B schematic calls for a 220pF on each grid. If only one went
bad,
> > wouldn't I see a different response by using only one tube and switching
> it
> > from one socket to the other?
> > What do you think about the disc/electrolytic combination between the
> > bias-set resistor and the RF choke? This may be just a filter for the
> ripple
> > on the half-wave rectified bias, but they are common to both tubes. so
if
> > one was leaking, wouldn't it pull both grids down by the same amount? I
> > can't read my schematic very well, but it looks like they are a 0.01 uF
> disc
> > to ground in parallel with a 2 uF/25V electrolytic to ground (although
the
> > parts list calls it a 2.2uF/50V - more likely).
> >
> > The 2100F is laid out a little different, with a 10uF on the
> relay/grid/bias
> > board.
> >
> > All comments appreciated.
> >
> > Rick, WD8JJA.
> >
> >
> > ----- Original Message -----
> > From: "Peter Frenning, OZ1PIF" <oz1pif@get2net.dk>
> > To: "R_Davis" <WD8JJA@arrl.net>; "H & W Electronics"
> > <info@handwelectronics.com>; <Fox_Tango@mailman.qth.net>;
> > <amps@contesting.com>
> > Sent: Monday, October 27, 2003 3:32 AM
> > Subject: Re: [Amps] FL-2100F
> >
> >
> > > Hi Rick,
> > >
> > > Check very carefully the two caps tying the grids to ground, I believe
> > they
> > > are C8-9 220pF in your version.
> > > I had exactly the same symptoms in my FL2000B, with a set of new
> bottles,
> > > and not until I took it completely apart for conversion to a QB4/1100,
> did
> > I
> > > find that one of these caps had blown - split completely open, but
> > invisible
> > > from the outside!
> > >
> > > Vy 73 de OZ1PIF, Peter
> > >
> > > ********** OZ1PIF **************
> > > email: oz1pif(no-spam-filler)@get2net.dk
> > > http://hjem.get2net.dk/oz1pif
> > > Ph. +45 4619 3239
> > > Snailmail:
> > > Peter Frenning
> > > Ternevej 23
> > > DK-4130 Viby Sj.
> > > Denmark
> > > ***********************************
> > > ----- Original Message -----
> > > From: "R_Davis" <WD8JJA@arrl.net>
> > > To: "H & W Electronics" <info@handwelectronics.com>;
> > > <Fox_Tango@mailman.qth.net>; <amps@contesting.com>
> > > Sent: Monday, October 27, 2003 4:15 AM
> > > Subject: [Amps] FL-2100F
> > >
> > >
> > > > Copy to AMPS reflector.
> > > >
> > > > H & W Electronics <info@handwelectronics.com>:
> > > >
> > > > Did you get a satisfactory answer to this, yet?
> > > >
> > > > I have an FL-2100B with similar symptoms.
> > > > I used to have normal (~.090) bias, was able to drive it to >
500mils,
> > and
> > > > it put out 700 - 800 watts peak normally (more if I crowded it).
Now
> I
> > > get
> > > > only about 60 mA bias, can only drive it to 250-300 mA, and get 300
> > watts
> > > > out, at best. Also, driving it real hard, the LOAD control stays at
> or
> > > near
> > > > 0.
> > > > Those are my symptoms.
> > > >
> > > > Possible related causes: One time, I accidentally was tuning into
the
> > > > internal dummy load of my Dentron MT-3000A which is rated for 200
> watts
> > > and
> > > > is protected by an internal fuse. I popped the fuse, but quit as
soon
> as
> > I
> > > > saw the SWR skyrocket.
> > > > On another occasion, and I cannot remember if it was before or
after,
> I
> > > > heard a "TINK" from the amp.
> > > > Neither time did I notice these symptoms immediately, but it has
only
> > been
> > > a
> > > > few months since the blown fuse and the "TINK".
> > > >
> > > > Is the concensus that the tubes are now soft? Funny thing, I
checked
> it
> > > > with one tube at a time, and with either tube in either socket, I
can
> > > drive
> > > > it to over 200 mA, maybe even 250 with my FT-101E. But I can't get
> 500
> > mA
> > > > with both tubes in. HV still looks good @ 2400V, dropping to around
> 2200
> > > > under load. ALC action looks normal, but at only about 300 watts
out.
> I
> > > > haven't cut the ALC line yet to see if it is holding it back. I
don't
> > > think
> > > > it is since I.C. on the exciter looks normal.
> > > >
> > > > Any suggestions before I by a new set of bottles??
> > > >
> > > > Rick, WD8JJA.
> > > > ----- Original Message -----
> > > > From: "H & W Electronics" <info@handwelectronics.com>
> > > > To: <Fox_Tango@mailman.qth.net>
> > > > Sent: Monday, October 20, 2003 11:29 PM
> > > > Subject: [Fox_Tango] FL-2100F
> > > >
> > > >
> > > > > Hi All!
> > > > > Anyone ever had low reading on the bias current? This one does
> only
> > > > > .06 while spec is .09. What gives?
> > > > >
> > > > > Now, more than ever, QSL.NET is in urgent need of your financial
> > > support.
> > > > >
> > > > > Please help QSL.NET by sending a donation now.
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