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[Amps] Tank Circuit Help

To: <amps@contesting.com>
Subject: [Amps] Tank Circuit Help
From: stevek@jmr.com (Steve Katz)
Date: Thu, 12 Sep 2002 08:21:49 -0700
> Hello Steve
> No the pic of the roller with the wires on is the pic the person took whom
> i got it from.
> You speak of flashing material, are you talking about the aluminum
> Flashing like you use on your house? What cut it in strips and use it ?
> 
        [Steve Katz]  Aluminum will work, but I'd use copper.
Roof/chimney/gutter flashing sold in Home Depot and, better, in industrial
construction material outlets, is available in aluminum, galvanized steel,
and copper.  For "our" purposes, copper's best, I'd stick with it.  I buy it
by the foot, from a coil, at the local lumber yard.  Thickness isn't
terribly important, other than it being thick enough to not tear or be
easily damaged, but width is important.  For interconnecting tank
components, I use tin snips or heavy-duty scissors to cut the flashing into
1" wide strips, and drill holes through the ends to make nut & bolt
connections.

> I have a roll of that somewhere i think if that is what  you are talking
> about.
> The roller seems to be in really good shape it came out of a Gates/Harris
> 1.6-30mhz transmitter.
> The coil for 10/12 what size copper tubing would be good to use for this i
> figure this thing will have a pep output around 4k. I have seen alot of
> people use a flat looking copper type material to make coils with ?
> 
        [Steve Katz]  You could use more of the same copper flashing
discussed above.  I often use 1/4" diameter copper tubing (plumbing supply
store) coiled onto a 1-1/4" dowel or pipe to form it.  It forms easier,
without kinking or damage, if you pinch one end of the tubing closed, pour
playground sand into the tubing to fill it up, then pinch the other end
closed.  Now, it cannot deform.  If you want, when you finish the work and
drill holes in the flattened tubing ends for nut & bolt attachments, you can
pour out the sand!  (I don't even bother.) -WB2WIK/6

> I want to thank you for taking the time to answer my questions.
> Chris
> 
> Steve Katz wrote:
> 
> 
>       That's a large edge-wound roller, alright.  I agree with AG6K's
> comment
>       about using a separate tank inductor for 10m, maybe for 12m also,
> and
>       bypassing the roller on those bands -- its min inductance is
> probably too
>       large to be useful.  If you're using the parts as shown, including
> the
>       interconnecting wiring, I'd replace all that interconnecting wiring
> with
>       wide copper strap (not braid, solid strap like flashing material) to
> reduce
>       the interconnecting inductances.  The wiring shown, if used on the
> higher
>       bands (14+ MHz) could be a problem, I would think.  
>       
>       The roller you show has a lot of turns but is similar in
> construction to
>       what Henry Radio uses in most of their amps for the pi-section of
> their pi-L
>       networks.  Unfortunately, those have never been terribly reliable
> due to the
>       roller contact variable resistance and tension.  Possibly the one
> you have
>       there is better than the ones Henry makes (hope so).
>       
>       WB2WIK/6<
>       br>
>       "If everything seems under control, you're just not going fast
> enough." -
>       Mario Andretti
>       
> 
>               -----Original Message-----
>               From:   NI4L [ SMTP:ni4l@charter.net
> <mailto:SMTP:ni4l@charter.net>]
>               Sent:   Wednesday, September 11, 2002 8:52 PM
>               To:     Steve Katz
>               Subject:        Re: [Amps] Tank Circuit  Help
>               
>               Lets try it again.
>               
>               Steve Katz wrote:
>               
>               
>                       No picture was attached to this...
>                       
>                       "If everything seems under control, you're just not
> going fast
>               enough." -
>                       Mario Andretti
>                       
>               
>                               -----Original Message-----
>                               From:   NI4L [  SMTP:ni4l@charter.net
> <mailto:SMTP:ni4l@charter.net>
>               <mailto:SMTP:ni4l@charter.net>
> <mailto:SMTP:ni4l@charter.net>]
>                               Sent:   Wednesday, September 11, 2002 4:28
> PM
>                               To:     Steve Katz
>                               Subject:        Re: [Amps] Tank Circuit
> Help
>                               
>                               Steve here is a pic of the roller. It was
> being used in a
>               antenna tuner
>                               when i ran arcoss it.
>                               I talked them out o
>               f it. It Came from  Gates transmitter.
>               Not really sure
>                               what the current is.
>                               My plate transformer  has 2 taps 5400v and
> 3800v @ 3.5 amps.
>               But the 84
>                               like around 4kv
>                               Here is a pic of the cabinet i am tyring to
> put it all in.
>                               Chris 
>                               
>                               
>                               15D x 7w x 8h roller flat stock coil 3/8
> wide 1/8"spacing
>               between the
>                               plates.
>                               
>                               Steve Katz wrote:
>                               
>                               
>                               
>                               
>                               
>                                               Hello Steve
>                                               what i have is 500pf@10kv
> ,1000pf@10kv, the
>               roller inductor
>                               is 103uh rated
>                                               10kv.
>                                               
>                               
>                                               [Steve Katz]  Holy mackeral!
> You can fit
>               all that in a
>                               chassis?
>                                       103 uH??  At what 
>                               current??  (The voltage rating isn't
> important,
>                               unless the
>                                       turns are spaced so closely they arc
> to each other,
>               which is
>                               doubtful.)
>                                       Most roller inductors used in
> amateur amps are about
>               28uH.
>                                       
>                               
>                                               I have 4 doorknobs
> 1000pf@12kv and some
>               500pf 
>                                               The band switch is a switc
>               h craft model 88
>               13kv rated.
>                                               This is my first amp of this
> sort so i am
>               still not sure
>                               about some
>                                               things.
>                                               I have built 813s 811s and
> 572b amps but
>               nothing like this
>                               the GU-84B 
>                                               
>                               
>                                               [Steve Katz]  What makes the
> GU-84B any
>               different from some
>                               572B's
>                                       in parallel?  Same requirements,
> other than I guess
>               people using
>                               GU-84Bs are
>                                       often doing it without sockets.
> Plate load
>               impedance is Ep/Ip,
>                               regardless
>                                       of the tube(s)....
>                                       
>                               
>                                               So i can use the bandswitch
> to switch the
>               doorknobs in and
>                               out. 
>                                               
>                               
>                                               [Steve Katz]  Normally, one
> would do this
>               with 572B's, also.
>                                       Problem with a 1000pF vacuum
> variable is that,
>               usually, it re
>                               quires
>                               an awful
>                                       lot of shaft rotations (turns) to go
> from min to
>               max; compared with
>                               an
>                                       air-variable that does it in 180
> degrees.  So,
>               unless you have
>                               interesting
>                                       circuit alternativ
>               es, going from, say, the high end
>               of 10 meters to
>                               the low
>                                       end of 80 meters could be a lot of
> work (crank,
>               crank, crank).  
>                                       
>                               
>                                               I am still trying to get a
> mental picture. I
>               feel pretty
>                               stupid right now
>                                               :) 
>                                               Can you explain a little bit
> more in detail
>               how i would hook
>                               it up to use
>                                               all 4 compnets?
>                                               
>                               
>                                               [Steve Katz]  Assume you're
> building a
>               pi-net?  I figure all
>                               the
>                                       component parameters needed for
> reasonable Q at full
>               power
>                               (reasonable might
>                                       be in the 4~6 range) and determine
> how much padding
>               C I might want
>                               to switch
>                                       in for plate tuning, or loading, or
> both; normally
>               this is only
>                               desirable on
>                                       the lower bands like 80 and 160m,
> but even on 40m it
>               can be
>                               advantageous to
>                                       switch in some padding rather than
>                                having to crank a vacuum cap
>                               through 20
>                                       rotations.  Then, wire up the
> bandswitch to switch
>               in those padders
>               
>                               as
>                                       required.  Obviously, in a pi-net
> one end of any
>               capacitor is always
>                               at
>                                       ground potential, so you only need
> to switch in "one
>               end" of any cap
>                               you're
>                                       adding. -WB2WIK/6
>                                       
>                               
>                                               Thanks for taking time to
> help out
>                                               73
>                                               Chris NI4L
>                                               
>                                               Steve Katz wrote:
>                                               
>                                               
>                                               
>                                               
>                                                               Hello All
>                                                               I have a
> question that maybe
>               someone can
>                               help me out with.
>                                                               I am in the
> process of
>               building a GU84B
>                               amp.
>                                                               I have a 2
> vac var caps and
>               a roller
>                               inductor, I have a
>                                               bandswitch also 
>                                                               but is there
> really a need
>               to use the
>                               bandswitch  when you
>                                               use vac caps 
>                                                               and a roller
> inductor.
>               Pro/Cons?
>                                                               
>                                               
>                                                               [Steve Katz]
> Normally a
>               bandswitch is used
>                               at a minimum to
>                                               switch
>                                                       input tuned circuits
> per band.
>               Additionally, unless
>                               you have an
>                                               awfully
>                                                       large "load
>                               " vacuum
>                variable, a bandswitch is useful
>                               to switch in
>                                               loading
>                                                       padder capacitors
> for the lower
>               bands like 80 and
>                               160 meters...a
>                                               typical
>                                                       vacuum cap can't
> offer the kind of
>               maximum
>                               capacitance normally
>                                               required to
>                                                       load into 50 Ohms on
> those bands.
>               -WB2WIK/6
>                                                       
>                                                       
>                                               
>                                                               I am still a
> babe in the
>               woods on this so
>                               any help would begreatly 
>                                                               appreciated.
>                                                               Chris
>                                                               
>                                                               
>                                       
>       
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>                                               
>                                               
>                                               
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