[Hallicrafters] SX71 MOD, a reprise

Dan Cotsirilos K9DTC dcsfree at comcast.net
Wed Mar 8 15:58:02 EST 2006 

I will say only one thing only once, That MOD is about a copy rightable as 
changing a tire with a socket wrench or which way you comb your hair!

Dan K9DTC



----- Original Message ----- 
From: "GBrown" <gkbrown at gwi.net>
To: "Duane Fischer, W8DBF" <dfischer at usol.com>; "Philip Atchley" 
<Beaconeer at sbcglobal.net>; "Magoo" <magoo at isp.ca>; 
<hallicrafters at mailman.qth.net>
Sent: Wednesday, March 08, 2006 2:50 PM
Subject: Re: [Hallicrafters] SX71 MOD, a reprise


> Who said I took this from someone, YOU did. I was only passing on what I 
> had
> done to a restoration, and what I had come by on my own, no ones help.
> What YOU are doing is just plain harassment. You have a problem with me,
> get it out in the open. Don't HIDE behind some trumped up charge or
> allegation.
> Duane, be a man, take responsibility for your actions.
> Gary...
> ----- Original Message ----- 
> From: "Duane Fischer, W8DBF" <dfischer at usol.com>
> To: "Philip Atchley" <Beaconeer at sbcglobal.net>; "Magoo" <magoo at isp.ca>;
> <hallicrafters at mailman.qth.net>
> Sent: Wednesday, March 08, 2006 2:57 PM
> Subject: Re: [Hallicrafters] SX71 MOD, a reprise
>
>
>> Phil (and all)
>>
>> When someone takes the copyrighted work of another without permission, or
>> does so with permission, you always credit the source and the author. To
> do
>> otherwise is theft and/or plagerism, depending on whether or not the
> person
>> taking said material 'claims' to be the author. What Gary Brown did was
>> wrong and unethical.
>>
>> Whether it is donated or whether it is not, what is on the HCI web site 
>> is
>> copyrighted under that entity. If someone wants to reprintn something,
> they
>> need to get permission from the Web Master first.
>>
>> Gary is just complaining because once again he got caught being dishonest
>> and is trying to pass the buck elsewhere.
>>
>> The HCI policy is clearly stated. If you wish to reprint an item or 
>> photo,
>> ask the Web Master first. Then credit the source and the author or
>> contributor. What is there is for the benefit of all, but we also have an
>> obligation to those who donate their work to protect it from theft, 
>> misuse
>> etc. Not all of what is on the HCI web site is donated! Hence the "Get
>> Permission First" policy.
>>
>> Duane Fischer, W8DBF
>>
>> ----- Original Message ----- 
>> From: "Philip Atchley" <Beaconeer at sbcglobal.net>
>> To: "Magoo" <magoo at isp.ca>; <hallicrafters at mailman.qth.net>
>> Sent: Wednesday, March 08, 2006 10:14 AM
>> Subject: [Hallicrafters] SX71 MOD, a reprise
>>
>>
>> > Hi All,
>> >
>> > Sheesh, if I'd have realized what a firestorm all this was going to
> create
>> > I would have kept my mouth shut, or rather, my fingers off the 
>> > keyboard!
>> >
>> > Anything that I submit or come up with, whether on my web site or via
>> > Email, is for the full benefit of the boatanchor community.  The SX71
>> > "mod" (which I first posted in the form of an Email and which was
>> > subsequently copied to the HCI site with my approval) that I came up
> with
>> > was 'slightly' more than just the cathode resistor, I also changed the
>> > screen bias etc. of the second stage.  Still, all pretty simple stuff.
>> > All that the HCI folks did was copy my email to the Web-site and add
> some
>> > advertising pictures to make it interesting.
>> >
>> > As far as I'm concerned, the written part that I produced can be 
>> > printed
>> > and may be freely used anywhere so long as there isn't any monetary
>> > compensation (though if it's copied to any web-site etc. I'd appreciate
>> > credit).  So far as I know, the PICTURES ARE HCI PROPERTY and any 
>> > needed
>> > permission should be definitely be obtained to use them.
>> >
>> > Since I originally wrote the article, and only parts of it made it's
> away
>> > "around the circuit",  I'm re-posting a copy here from my own archives.
>> > Enjoy!
>> >
>> > <Pasted in>
>> > I decided to take a '2nd' look at the SX-71.  While it played quite 
>> > well
> I
>> > never felt like it was doing all that a receiver with 3 IF stages 
>> > should
>> > do. Front end seemed sensitive enough, but overall gain and AGC action,
>> > while a little better than 'most' receivers with 2 IF's like the
>> > Hammarlund HQ-100, Halli SX-110 etc, just didn't seem to really have 
>> > the
>> > "punch".  After I overhauled Don's National NC183D that had 3 IF's and 
>> > a
>> > circuit design quite similar to the SX-71, that opinion was further
>> > reinforced.  In that set I had to change a couple resistors (per 
>> > factory
>> > recommendation) to decrease the gain slightly as it was unstable.
>> >
>> > So anyway, I sat down with the schematic and tube manual to see if I
> could
>> > determine why it's gain seemed so modest for the tube lineup.  Didn't
> take
>> > me long to spot it.  The 2nd IF stage had it's tube cathode biased very
>> > high and an unusually low screen Voltage on the screen grid.  So, I dug
>> > out ye old trusty soldering iron and set the cathode resistor and 
>> > screen
>> > Voltage to the same level that the 1st and 3rd IF stages use, which is 
>> > a
>> > normal and expected value.  Voila! Gain and AGC action came up to my
>> > expectations.  It won't affect overall sensitivity/noise figure as that
> is
>> > mostly determined by the RF amplifier and first mixer stages.  What it
>> > does affect, especially on the higher frequencies is how well the AGC
>> > performs and how high you need to turn the volume on the weak stations.
>> > Before you always had to 'crank it up' on weak stations on the 17 &
> 21MHz
>> > bands, which is why I nearly always used the Ameco Nuvistor preamp over
> 15
>> > MHz.  The thing really sounds good now and that is without the preamp!
>> >
>> > The SX-71 is claimed to be the first double conversion set on the
> market.
>> > They also wanted the selectivity and perhaps a 'little' extra gain that
> an
>> > extra IF amplifier gave them.  I can think of no explanation of why the
>> > receiver was purposely 'tamed down' by crippling the 2nd IF and putting
>> > coils that are sub par for the BCB band in an otherwise hot set.
> Perhaps
>> > 3 IF stages were so rare back then that they felt the "little" added
> boost
>> > was sufficient, while now days we are used to all receivers having
> several
>> > AGC controlled stages that give superb AGC action.
>> >
>> > <end of article>
>> >
>> > 73 de Phil,  KO6BB
>> > DX begins at the noise floor!
>> >
>> > THE BEACONEER'S LAIR:  http://www.geocities.com/ko6bb/
>> > MY RADIO-LOGS:   http://www.geocities.com/ko6bb/Logs/
>> > QSL GALLERY:       http://photobucket.com/albums/y123/KO6BB/
>> > Merced, Central California,    37.3N  120.48W  CM97sh
>> >
>> >
>> > ----- Original Message ----- 
>> >
>> >> Let's see if I have this sequence right-
>> >>
>> >> Someone discovers that changing a resistor in a stage leads to better
>> >> performance and posts this for everyone's benefit.
>> >>
>> >> Someone else posts a message indicating that this mod is similar to 
>> >> one
>> >> found in a pre-written article. That article is identified with a link
>> >> for everyone to see.
>> >>
>> >> The author of this earlier article contacts the list administrator to
>> >> protest that someone has hijacked his material without giving him
> credit.
>> >>
>> >> Right so far?  OK-so if I discover a mod for a radio and post it for
>> >> everyone's benefit, not knowing that someone else has "discovered" 
>> >> this
>> >> earlier and written an article on it then I am contravening 
>> >> "copyright"
>> >> laws?
>> >>
>> >> Horse puckey!!  Let's get real!  I know Americans are a litiginous
>> >> society but let's not get carried away here.  This is ham radio, not
> the
>> >> great Blackberry steal.
>> >>
>> >> Bill, VE3NH
>> >
>> > ______________________________________________________________
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>> > ----
>> > List Administrator: Duane Fischer, W8DBF **for assistance**
>> > dfischer at usol.com
>> > ----
>> > Hallicrafters Collectors International: http://www.w9wze.org
>> >
>> >
>> >
>> > -- 
>> > No virus found in this incoming message.
>> > Checked by AVG Free Edition.
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>> >
>>
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>> ----
>> List Administrator: Duane Fischer, W8DBF **for assistance**
>> dfischer at usol.com
>> ----
>> Hallicrafters Collectors International: http://www.w9wze.org
>>
>
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> ----
> List Administrator: Duane Fischer, W8DBF **for assistance**
> dfischer at usol.com
> ----
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