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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> >
>
>
>
>
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