[Amps] GS35B on 144 Mhz
Glenn McNeil
vk4tzl at bigpond.net.au
Sun Jan 22 23:03:16 EST 2006
Hi Guys,
I'm just in the final stages of tuning up a GS35B on 144 MHx. The
original design was down by DJ5RE. It is featured on the N2DX QRO Russia
Site as a project by DG2KBC.
It has all gone together quite well, till I got to running a bit of
power into it. The Input side of things has tuned up well, with a low
SWR. However, I'm am having trouble with the Anode Tuning. As I am a
Ham, I changed things...instead of using a Flapper for Anode Tuning, I
tracked down some very nicely made brass Anode and RF Output threaded
Rods with Brass Disks on the end. I now have an 80mm Diameter Brass Disc
that approaches the side of the GS35B Anode cooler from the front panel
at right angles to the Cooler.
The threaded rod runs in a brass sleeve, that is firmly screwed to the
front panel, that can be locked with set scew when you get the tuning
right. In my mind, it achieves the same result as the brass flapper that
does exactly the same thing, but much more crudely.
My problem...on initial tune up using my h/held with about 2.5 watts
output, I could not get any hint of tuning...more a slight increase in
power as I wound the Anode Tuning Disc away from the Anode Cooler. I
figure that the plate line may to too long ( 240mm * 60 wide * 1.6mm
thick ) I shortened the length by around 12mm and found that I could now
get reasonable power out...around 60w with 2 w input, but the tuning
still is at max distance from the tube with no "peak". I made up
another Anode Line, shorter again at 214mm. Result....the same...Moving
the Disc away from the Anode till I run out of Thread just sees the
Power increase.
Getting brave, I hit it with 25W....now I see around 300W Output, about
300ma Anode I with 100ma Standing bias and 2800v on the Anode. It seems
stable, but its got me stumped why I cannot get the Anode to tune with
the Disc in nice and close ( which is where I would assume it would be,
as way out from the Tube it cannot be having much effect ) I can't
believe that the Anode Line is still too long...maybe it is. Anyone got
a simple way of proving this ?
At the moment, thinking about it, I could remove the Anode Tuning Disc
altogether and get max power out...doesn't sound right does it ?
This is my first Large Russian Triode, so I'm moving very carefully lest
I let loose a small mushroom shaped cloud and really scare myself :)
The Amp is protected by a G3SEK Board and all DC Conditions look OK. I
will be running more Anode Volts when I get then thing behaving, but at
present it is spread all over the bence with a different Anode Supply
running it.
Any thoughts ??
73
Glenn
VK4TZL
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>Today's Topics:
>
> 1. Re: Tuned Input (w6ah at comcast.net)
> 2. Info needed (Dan Hearn)
> 3. input ckts. (carl s.)
> 4. Re: Tuned Input (Tony King - W4ZT)
> 5. Building or Buying a Tuned Input Network (Bob Selbrede, K6ZZ)
> 6. Re: Building or Buying a Tuned Input Network (Tony King - W4ZT)
> 7. Re: Building or Buying a Tuned Input Network (Hector Garcia XE2K)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Sun, 22 Jan 2006 21:38:32 +0000
>From: w6ah at comcast.net
>Subject: Re: [Amps] Tuned Input
>To: amps at contesting.com
>Message-ID:
> <012220062138.15363.43D3FB580004C3F900003C032207300793080EC099 at comcast.net>
>
>Content-Type: text/plain; charset="us-ascii"
>
>Allow me to provide clarification. I wrote: "A work around that he found was to remove the output cap on the input network bandswitch and attach it directly to the tube cathode." That should read:
>
>A work around that he found was to remove the output cap for the 10 Meter band mounted on the input network bandswitch and attach it directly to the tube cathode.
>
>Apologies to those I may have confused.
>
>73s
>
>Bob W6AH
>
>-------------- Original message --------------
>From: w6ah at comcast.net
>
>
>
>>Right you are Karl Arne.
>>
>>Using any type of coax between the output side of the network and the tube
>>cathode is an open invitation for trouble. At harmonic frequencies that piece of
>>coax can look like a quarter wave matching network ! Depending on the frequency
>>and length of coax involved.
>>
>>In amplifier design component placement is the name of the game and the input
>>network is no exception. Mount that network as close to the cathode as possible
>>and use a piece of copper strap or heavy coax (RG213) outer conducter braid to
>>attach the two mindful to keep the lead length short.
>>
>>I went to school with a ham that later became a design engineer for RL Drake.
>>Among his responsibilities was the design of the L75 Amp. I had a conversation
>>with him 6 years ago and he spoke of some of the obstacles he had to overcome.
>>One was the problem of Low Output and poor efficiency on 10 meters. A work
>>around that he found was to remove the output cap on the input network
>>bandswitch and attach it directly to the tube cathode. What that accomplished
>>was to add the stray inductance of the connection lead to the input inductor.
>>Then it became a simple matter to reduce the inductor size for proper operation.
>>On the lower bands the output capacitors on the switch were removed and reduced
>>values installed to reflect a total network capacitance of the two combined to
>>reflect the proper value. The only drawback to this scheme is the stray
>>inductance then becomes a second inductor forming a "Double Pi" on the lower
>>bands. But he found that even on 15 meters the stray inductance
>>was low enough to have minimal effect. In effect what this approach did was to
>>transfer the problem to a frequency where it was much more managable to deal
>>with.
>>
>>73s
>>
>>Bob W6AH
>>
>>-------------- Original message --------------
>>From: Karl-Arne Markström
>>
>>
>>>The use of a long coaxial line between the driver and the untuned input of a
>>>GG amplifier has other drawbacks.
>>>
>>>For the fundamental frequency component, the line may appear as a shunt
>>>capacitance,
>>>but with increasing harmonic numbers the effects
>>>of the coaxial line electrical length and its termination
>>>may result in high equivalent series impedances in series with the RF plate
>>>current flow.
>>>
>>>73/
>>>
>>>Karl-Arne
>>>SM0AOM
>>>
>>>
>>>----- Original Message -----
>>>From: "Gary Schafer"
>>>To: ; "'Tony King - W4ZT'" ;
>>>"'AMPS'"
>>>Cc:
>>>Sent: Sunday, January 22, 2006 4:59 AM
>>>Subject: Re: [Amps] Tuned Input
>>>
>>>
>>>
>>>
>>>>Could you elaborate a little more on this?
>>>>
>>>>Why is the efficiency less when a coil input is at the cathode?
>>>>
>>>>Also wouldn't "too much coax" provide extra capacitance to ground?
>>>>
>>>>I assume that the harmonic that you're talking about is second harmonic
>>>>energy? Why do we care if it is attenuated or not other than IM performance?
>>>>
>>>>Thanks
>>>>Gary K4FMX
>>>>
>>>>
>>>>
>>>>
>>>>>-----Original Message-----
>>>>>From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>>>>>Behalf Of George badger
>>>>>Sent: Saturday, January 21, 2006 12:08 AM
>>>>>To: Tony King - W4ZT; AMPS
>>>>>Cc: skipp025 at yahoo.com
>>>>>Subject: Re: [Amps] Tuned Input
>>>>>
>>>>>I have been using an antenna tuner as an input circuit
>>>>>for my HB 8877 lineart for years. When I was at EIMAC
>>>>>I learned that when linear amplifier OEMs complained
>>>>>of low efficiency it was often caused by too much
>>>>>inductance in the input cathode drive cicuit. For
>>>>>example, a T input circuit (LCL} was a disaster on 40
>>>>>and 80. Similarly, if the lead from the input pi
>>>>>network to the cathode is too long, a problem is
>>>>>created on 10M. The reason is that the cathode current
>>>>>is not sinusoidal so harmonic current must have an
>>>>>easy path to ground. Unless there is sufficint
>>>>>capacitance to ground, efficiency suffers.
>>>>>To avoid this on my linear,I experimented with
>>>>>a variable capacitor to determine the largest fixed
>>>>>capacitor I could get away with and still be within
>>>>>the range of my drake tuner on all bands The
>>>>>capacitance turned out to be 50 pfd. It is connected
>>>>>directly from cathode to ground with short leads.
>>>>>W6TC
>>>>>--- Tony King - W4ZT wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Ian White, GM3SEK wrote:
>>>>>>
>>>>>>
>>>>>>>Roger D Johnson wrote:
>>>>>>>
>>>>>>>
>>>>>>>>Tony King - W4ZT wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>>I don't know if any of you have looked into this
>>>>>>>>>
>>>>>>>>>
>>>>>>particular product but
>>>>>>
>>>>>>
>>>>>>>>>at first glance it appears that this is one
>>>>>>>>>
>>>>>>>>>
>>>>>>solution for the tuned input
>>>>>>
>>>>>>
>>>>>>>>>problem many of us face and at the right price
>>>>>>>>>
>>>>>>>>>
>>>>>>too:
>>>>>>
>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>73, Tony W4ZT
>>>>>>>>>
>>>>>>>>>
>>>>>>>>The purpose of the tuned input is to provide a
>>>>>>>>
>>>>>>>>
>>>>>>"flywheel" effect to
>>>>>>
>>>>>>
>>>>>>>>smooth out the variations of amplifier input
>>>>>>>>
>>>>>>>>
>>>>>>impedance over the
>>>>>>
>>>>>>
>>>>>>>>operating cycle. The Q of the circuit determines
>>>>>>>>
>>>>>>>>
>>>>>>how much "flywheel"
>>>>>>
>>>>>>
>>>>>>>>effect we have. The lowest recommended value I've
>>>>>>>>
>>>>>>>>
>>>>>>seen is 2. Solid
>>>>>>
>>>>>>
>>>>>>>>state transceivers want even more...perhaps 3 to
>>>>>>>>
>>>>>>>>
>>>>>>5.
>>>>>>
>>>>>>
>>>>>>>>The LDG tuner is an L network in which the Q is
>>>>>>>>
>>>>>>>>
>>>>>>dependent on the ratio
>>>>>>
>>>>>>
>>>>>>>>of impedances to be matched. For normal input
>>>>>>>>
>>>>>>>>
>>>>>>impedances, the resulting
>>>>>>
>>>>>>
>>>>>>>>Q will be very low. It's hard to write the
>>>>>>>>
>>>>>>>>
>>>>>>formula in text format but
>>>>>>
>>>>>>
>>>>>>>>in words it's as follows: divide the higher
>>>>>>>>
>>>>>>>>
>>>>>>impedance by the lower,
>>>>>>
>>>>>>
>>>>>>>>subtract 1 and then take the square root. For
>>>>>>>>
>>>>>>>>
>>>>>>example to match an
>>>>>>
>>>>>>
>>>>>>>>impedance of 100 ohms to 50 ohms, the resulting Q
>>>>>>>>
>>>>>>>>
>>>>>>is only 1!
>>>>>>
>>>>>>
>>>>>>>>With a 3 terminal network you can choose the Q
>>>>>>>>
>>>>>>>>
>>>>>>independently of the
>>>>>>
>>>>>>
>>>>>>>>matching and would seem to be the way to go.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>The recommendation for an input tuned circuit Q of
>>>>>>>
>>>>>>>
>>>>>>2-4 came from a 1961
>>>>>>
>>>>>>
>>>>>>>article by Eimac authors in QST. That
>>>>>>>
>>>>>>>
>>>>>>recommendation was specifically
>>>>>>
>>>>>>
>>>>>>>based on a pi tank, and it was also pointed out
>>>>>>>
>>>>>>>
>>>>>>that the output
>>>>>>
>>>>>>
>>>>>>>capacitor provides a direct shunt path from
>>>>>>>
>>>>>>>
>>>>>>cathode to ground for
>>>>>>
>>>>>>
>>>>>>>circulating harmonic currents. But when an
>>>>>>>
>>>>>>>
>>>>>>L-network is being used in
>>>>>>
>>>>>>
>>>>>>>impedance step-down mode, it doesn't even have an
>>>>>>>
>>>>>>>
>>>>>>output C.
>>>>>>
>>>>>>
>>>>>>>Now it may be that the designers know all about
>>>>>>>
>>>>>>>
>>>>>>these things, have
>>>>>>
>>>>>>
>>>>>>>checked their effects on amplifier IMD
>>>>>>>
>>>>>>>
>>>>>>performance, and have found some
>>>>>>
>>>>>>
>>>>>>>reason to ignore the Eimac recommendations. If
>>>>>>>
>>>>>>>
>>>>>>that is the case, it
>>>>>>
>>>>>>
>>>>>>>would be good to hear why.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>73 from
>>>>>>>Ian GM3SEK
>>>>>>>
>>>>>>>
>>>>>>These are very good points that raise questions that
>>>>>>must be answered
>>>>>>before I would consider using such a tuner as the
>>>>>>input circuit. I'm
>>>>>>with you Ian, I'd like to see the answers to the
>>>>>>questions.
>>>>>>
>>>>>>It's been said many times that the best input
>>>>>>circuit is a pi-network
>>>>>>which will provide the fly-wheel effect to help
>>>>>>smooth the dynamic
>>>>>>changes in input impedance. As Skipp025 said, on
>>>>>>another list, "The
>>>>>>automated antenna tuners might tend to hunt around
>>>>>>looking for the best
>>>>>>match." If that happens, we've just moved the
>>>>>>problem from the
>>>>>>transceiver to the amp.
>>>>>>
>>>>>>Bill, WA4LAV, has an interesting suggestion about
>>>>>>shunting the cathode
>>>>>>with a capacitor and I wonder what everyone thinks
>>>>>>of that?
>>>>>>
>>>>>>73, Tony W4ZT
>>>>>>
>>>>>>
>>>>>>_______________________________________________
>>>>>>Amps mailing list
>>>>>>Amps at contesting.com
>>>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>>>
>>>>>>
>>>>>>
>>>>>_______________________________________________
>>>>>Amps mailing list
>>>>>Amps at contesting.com
>>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>>
>>>>>
>>>>_______________________________________________
>>>>Amps mailing list
>>>>Amps at contesting.com
>>>>http://lists.contesting.com/mailman/listinfo/amps
>>>>
>>>>
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>>>>No virus found in this incoming message.
>>>>Checked by AVG Free Edition.
>>>>Version: 7.1.375 / Virus Database: 267.14.21/236 - Release Date: 2006-01-20
>>>>
>>>>
>>>>
>>>--
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>>>Checked by AVG Free Edition.
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>>>
>>>_______________________________________________
>>>Amps mailing list
>>>Amps at contesting.com > http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>
>------------------------------
>
>Message: 2
>Date: Sun, 22 Jan 2006 14:07:12 -0800
>From: "Dan Hearn" <dhearn at wwnw.net>
>Subject: [Amps] Info needed
>To: "amps" <amps at contesting.com>
>Message-ID: <ACEGINBFNLHLHJAHIHCPEEILCJAA.dhearn at wwnw.net>
>Content-Type: text/plain; charset="iso-8859-1"
>
>I recently acquired several HV rectifier units from an estate sale. A Google
>search did not give me information on them. Any help in determining their
>voltage and current ratings will be appreciated.
>1. Unitrode UDA5. It looks like and has the same dimensions as a UDE5 on the
>Surplus Sales Nebraska site.
>2. Varo VC80X
>3. Semtec SDHD 15K. Also SDHD 5K
>4. Solitron C711 7410
>5. IRC 6809
>Tnx, Dan, N5AR
>
>
>
>------------------------------
>
>Message: 3
>Date: Sun, 22 Jan 2006 18:07:54 -0500
>From: "carl s." <carlseye at tampabay.rr.com>
>Subject: [Amps] input ckts.
>To: <Amps at contesting.com>
>Message-ID: <010001c61fa8$adbdc620$7524fea9 at tampabay.rr.com>
>Content-Type: text/plain; charset="iso-8859-1"
>
> Does all this info on input ckts. apply to both directly and and
>indirectly heated tubes.?? Seems to me it should, but want an expert (?)
>opinion!!!!!!
> thanks !!!
> CARL . KZ5CA
>
>
>
>
>------------------------------
>
>Message: 4
>Date: Sun, 22 Jan 2006 19:00:38 -0500
>From: Tony King - W4ZT <amps080605 at w4zt.com>
>Subject: Re: [Amps] Tuned Input
>To: "carl s." <carlseye at tampabay.rr.com>
>Cc: Amps at contesting.com
>Message-ID: <43D41CA6.8050105 at w4zt.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>yes. 73, Tony W4ZT
>
>carl s. wrote:
>
>
>> Does all this info on input ckts. apply to both directly and and
>>indirectly heated tubes.?? Seems to me it should, but want an expert (?)
>>opinion!!!!!!
>> thanks !!!
>> CARL . KZ5CA
>>
>>
>
>
>------------------------------
>
>Message: 5
>Date: Sun, 22 Jan 2006 18:31:18 -0800
>From: "Bob Selbrede, K6ZZ" <k6zz at ccis.com>
>Subject: [Amps] Building or Buying a Tuned Input Network
>To: amps at contesting.com
>Message-ID: <43d43ff6.3d0.5b64.342172725 at mail.ccis.com>
>Content-Type: text/plain; charset="iso-8859-1"
>
>Hi Folks,
>
>I would like to build or buy a tuned input network
>(160M-10M) for an amp running a pair of 3CX800A7's. Here
>are my thoughts so far. Comments appreciated.
>
>Buy:
>
>So far, I haven't found anyone on the web building and
>selling tuned input networks suitable for this application.
>I could probably just buy one of those LDG units that was
>mentioned on the AMPS List the other day, but it seems like
>overkill. After the values for the input matching network
>are know and set, they most likely won't change so an
>autotuner seems to provide features that aren't really
>necessary. Then again, for $125 maybe, it may be worthwhile
>in the long run.
>
>Another thought would be to buy a tuned input board for an
>existing commercial amplifier such as the Ameritron AL-800H.
> I'm not sure how much it would cost, but it runs a pair of
>3CX800A7's so it would most likely work fine.
>
>Are there other "buy" alternatives? I called Omega
>Electronics and they apparently don't have any more tuned
>input boards on hand.
>
>Build:
>
>Building a tuned input network seems pretty straightforward.
> A switchable PI network with tunable slug inductors seems
>like a good approach. I'm assuming that the input impedance
>for the tubes would be approximately 25 Ohms so I would be
>looking at matching 50 Ohms to 25 Ohms from 160M through
>10M. Shooting for a Q of 2-4 I should be able to use a PI
>network calculator to get the proper component values.
>Sound about right?
>
>Another approach would be to build the network utilizing the
>same component values as used in the AL-800H or other 2x
>3CX800A7 amplifier input circuit?
>
>Am I overlooking any other build/buy alternatives?
>
>73, Bob K6ZZ
>
>
>
>------------------------------
>
>Message: 6
>Date: Sun, 22 Jan 2006 22:14:41 -0500
>From: Tony King - W4ZT <amps080605 at w4zt.com>
>Subject: Re: [Amps] Building or Buying a Tuned Input Network
>To: amps at contesting.com
>Message-ID: <43D44A21.2000903 at w4zt.com>
>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>Take a look at Paul's (WD7S) tuned input board:
><http://home.earthlink.net/%7Ewd7s/TU-6B.htm>
>
>73, Tony W4ZT
>
>
>Bob Selbrede, K6ZZ wrote:
>
>
>>Hi Folks,
>>
>>I would like to build or buy a tuned input network
>>(160M-10M) for an amp running a pair of 3CX800A7's. Here
>>are my thoughts so far. Comments appreciated.
>>
>>Buy:
>>
>>So far, I haven't found anyone on the web building and
>>selling tuned input networks suitable for this application.
>>I could probably just buy one of those LDG units that was
>>mentioned on the AMPS List the other day, but it seems like
>>overkill. After the values for the input matching network
>>are know and set, they most likely won't change so an
>>autotuner seems to provide features that aren't really
>>necessary. Then again, for $125 maybe, it may be worthwhile
>>in the long run.
>>
>>Another thought would be to buy a tuned input board for an
>>existing commercial amplifier such as the Ameritron AL-800H.
>> I'm not sure how much it would cost, but it runs a pair of
>>3CX800A7's so it would most likely work fine.
>>
>>Are there other "buy" alternatives? I called Omega
>>Electronics and they apparently don't have any more tuned
>>input boards on hand.
>>
>>Build:
>>
>>Building a tuned input network seems pretty straightforward.
>> A switchable PI network with tunable slug inductors seems
>>like a good approach. I'm assuming that the input impedance
>>for the tubes would be approximately 25 Ohms so I would be
>>looking at matching 50 Ohms to 25 Ohms from 160M through
>>10M. Shooting for a Q of 2-4 I should be able to use a PI
>>network calculator to get the proper component values.
>>Sound about right?
>>
>>Another approach would be to build the network utilizing the
>>same component values as used in the AL-800H or other 2x
>>3CX800A7 amplifier input circuit?
>>
>>Am I overlooking any other build/buy alternatives?
>>
>>73, Bob K6ZZ
>>
>>_______________________________________________
>>Amps mailing list
>>Amps at contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>>
>
>
>------------------------------
>
>Message: 7
>Date: Sun, 22 Jan 2006 19:33:15 -0800 (PST)
>From: Hector Garcia XE2K <j_hector_garcia at sbcglobal.net>
>Subject: Re: [Amps] Building or Buying a Tuned Input Network
>To: k6zz at ccis.com, amps at contesting.com
>Message-ID: <20060123033315.26821.qmail at web81108.mail.mud.yahoo.com>
>Content-Type: text/plain; charset=iso-8859-1
>
>Bob:
>
>this option works for you ?
>
>http://home.earthlink.net/~wd7s/TU-6B.htm
>i found it several monts ago for the idea to add to
>the MLA2500
>
>
>--- "Bob Selbrede, K6ZZ" <k6zz at ccis.com> wrote:
>
>
>
>>Hi Folks,
>>
>>I would like to build or buy a tuned input network
>>(160M-10M) for an amp running a pair of 3CX800A7's.
>>Here
>>are my thoughts so far. Comments appreciated.
>>
>>Buy:
>>
>>So far, I haven't found anyone on the web building
>>and
>>selling tuned input networks suitable for this
>>application.
>>I could probably just buy one of those LDG units
>>that was
>>mentioned on the AMPS List the other day, but it
>>seems like
>>overkill. After the values for the input matching
>>network
>>are know and set, they most likely won't change so
>>an
>>autotuner seems to provide features that aren't
>>really
>>necessary. Then again, for $125 maybe, it may be
>>worthwhile
>>in the long run.
>>
>>Another thought would be to buy a tuned input board
>>for an
>>existing commercial amplifier such as the Ameritron
>>AL-800H.
>> I'm not sure how much it would cost, but it runs a
>>pair of
>>3CX800A7's so it would most likely work fine.
>>
>>Are there other "buy" alternatives? I called Omega
>>Electronics and they apparently don't have any more
>>tuned
>>input boards on hand.
>>
>>Build:
>>
>>Building a tuned input network seems pretty
>>straightforward.
>> A switchable PI network with tunable slug inductors
>>seems
>>like a good approach. I'm assuming that the input
>>impedance
>>for the tubes would be approximately 25 Ohms so I
>>would be
>>looking at matching 50 Ohms to 25 Ohms from 160M
>>through
>>10M. Shooting for a Q of 2-4 I should be able to
>>use a PI
>>network calculator to get the proper component
>>values.
>>Sound about right?
>>
>>Another approach would be to build the network
>>utilizing the
>>same component values as used in the AL-800H or
>>other 2x
>>3CX800A7 amplifier input circuit?
>>
>>Am I overlooking any other build/buy alternatives?
>>
>>73, Bob K6ZZ
>>
>>_______________________________________________
>>Amps mailing list
>>Amps at contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>>
>
>
>Hector Garcia XE2K / XF1K
>Mexicali B.C DM22
>
>
>------------------------------
>
>_______________________________________________
>Amps mailing list
>Amps at contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
>
>End of Amps Digest, Vol 37, Issue 64
>************************************
>
>
>
>
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