>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
*** My guess is that the choke has a self-resonance somewhere in the
neighborhood of the 572B's anode-circuit resonance. This problem is
common in the Henry 2K-4's and 3K-A's HV-RFC where 3-turns occasionally
get toasted. Do you have a dipmeter?
>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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>> > > > >
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>> > >
>> > >
>> > >
>> > >
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