[Hallicrafters] SX-71 Notes

Sun Feb 26 21:40:41 EST 2006

I have been reading with interest the various postings about this, my
favorite, Halli receiver.

I have restored two of them. In both instances I had to replace abou 95% of
the carbon resisitors. They had shifted value up to 300%!

The info on the audio caps and the cathode resistor is spot on!! Do it! You
won't regret it. I used all brand new orange drop caps, and went over
voltage any where I could. Likewise with the electrolytics. I over
engineered them, also. I replaced the coaxial lines going to and from the
2nd mixer....used RG-174 for the replacement as it is a lot smaller and only
handels signal voltages.

Interestingly on the 2nd restoral, once the resistors were replaced and the
unit recapped, it was fired up and under went alignment. The alignment was
pretty fast as there was very little to "tweak". The receiver fell right
into spec with very little "diddle-sticking" on my part. That was a
surprise.

It sits now on my end table in the living room. I fire it up almost daily
and listen to some SW bcst and some 80 M AM phone ops (3885 kc).

The SX-71 is a grand old Halli that is often times overlooked in favor of
the SX-62, SX-100, etc. If you get a chance to pick one up, by all means.

Speaking of the 2nd mixer: there are two different schematics of this mixer.
I went with th eone in the Sams Photofacts.
73

Rich K7SZ

The 2nd mixer (it sits above the chassis in it's own little "can")
----- Original Message ----- 
From: <hallicrafters-request at mailman.qth.net>
To: <hallicrafters at mailman.qth.net>
Sent: Sunday, February 26, 2006 8:48 PM
Subject: Hallicrafters Digest, Vol 25, Issue 39

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> Today's Topics:
>
>    1. SX-71 UPDATE (GBrown)
>    2. Re: SX-71 UPDATE (Oliver J. Dragon)
>    3. Re: SX-71 UPDATE (carolew)
>    4. WTB: lamp holders (Edward B Richards)
>    5. HT-37 Sideband Supression (Joe and Ann Vlk)
>    6. re Globe V-10 vfo (Fern Rivard)
>    7. Re: re Globe V-10 vfo (Glen Zook)
>    8. Head Scratcher (GBrown)
>    9. Re: HT-37 Sideband Supression (Mark Shaum)
>   10. RE: Head Scratcher (Bill Gerhold)
>   11. Re: Head Scratcher (amfone at sbcglobal.net)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 26 Feb 2006 08:47:32 -0500
> From: "GBrown" <gkbrown at gwi.net>
> Subject: [Hallicrafters] SX-71 UPDATE
> To: <hallicrafters at mailman.qth.net>
> Message-ID: <002e01c63adb$31e6dca0$40a7c3d8 at computer>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Just a few notes to anyone who mite be starting a recap job on a SX-71.
> First thing I done was cut the line cord of the radio. This removes the
> temptation to plug it in. I went over the schematic diagram, made notes of
> suspected areas of attack. Removed the one line bypass cap rated at 600
> volts and replace with one rated at 1.6kv. I also added another one to
other
> side of line. Next I jumped to the electrolytic and unsoldered all
> connections while drawing a little diagram. You never know, if your like
me,
> your going to forget which wire went where and spend time tracking down
the
> connection on the schematic. I did notice that when I removed the
> electrolytic can cap, two twist lugs were soldered to the chassis. LOOK
> AGAIN, it looks like there soldered but I will bet you the solder has
> separated or all most separated from the chassis. I tested the cap, all
> three sections were a little leaky so I restuffed it with NOS caps and
> reinstalled. I did resolder the two tabs to the chassis and also ran a
> ground from one of the tabs to a known good ground. Next area of
> concentration is the audio section. As we all know, Hallicrafters radios
are
> very susceptible to failure in the audio section. With no questions asked,
> changed out ALL the caps in this area. The cathode resistor had gone up
> about 300 ohms. This is a MUST change also in allot of radios with any
age.
> CHANGE THAT CATHODE RESISTOR. When you do change it, put one in that's a
> little bigger wattage, if possible. I had tested all the tubes. Seeing
they
> were all logoed Hallicrafters. Most were weak and one had an open
filament.
> If you have a capacitor checker, make sure to check all the micas and
those
> double duty disc ceramics. Well, that's about it for yesterday, will be
> headed back to the shop today to tackle some more areas that need
attention.
> Before I forget, I don't think I saw a line fuse in this radio.
> NOTE: Install line fuse when installing new three conductor power cord.
And,
> one other little tip. When you remove a component, just clip a jumper wire
> to where the part was. This saves some head scratching after you come back
> from dinner.
> All have a good weekend.
> Regards,
> Gary...WZ1M
>
>
>
> ------------------------------
>
> Message: 2
> Date: Sun, 26 Feb 2006 11:32:08 -0500
> From: "Oliver J. Dragon" <spress at rcn.com>
> Subject: Re: [Hallicrafters] SX-71 UPDATE
> To: "GBrown" <gkbrown at gwi.net>, <hallicrafters at mailman.qth.net>
> Message-ID: <6.0.0.22.0.20060226112142.029869c0 at pop.rcn.com>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> Gary,
>
> Thanks for the detailed description of your SX-71 recap. I am learning a
> lot from your
> notes and adding them to the file of experiences that you and others have
> passed along
> to the rest of us. These details will be of great help and guidance in the
> future as I tackle
> the recap of various boatanchors. I'm sure there are many others here that
> are storing
> (if only mentally) the info in personal archives.
> Please keep up the great work. Thanks again!
>
> Ollie
>
> At 08:47 AM 02/26/2006, GBrown wrote:
> >Just a few notes to anyone who mite be starting a recap job on a SX-71.
> >First thing I done was cut the line cord of the radio. This removes the
> >temptation to plug it in. I went over the schematic diagram, made notes
of
> >suspected areas of attack. Removed the one line bypass cap rated at 600
> >volts and replace with one rated at 1.6kv. I also added another one to
other
> >side of line. Next I jumped to the electrolytic and unsoldered all
> >connections while drawing a little diagram. You never know, if your like
me,
> >your going to forget which wire went where and spend time tracking down
the
> >connection on the schematic. I did notice that when I removed the
> >electrolytic can cap, two twist lugs were soldered to the chassis. LOOK
> >AGAIN, it looks like there soldered but I will bet you the solder has
> >separated or all most separated from the chassis. I tested the cap, all
> >three sections were a little leaky so I restuffed it with NOS caps and
> >reinstalled. I did resolder the two tabs to the chassis and also ran a
> >ground from one of the tabs to a known good ground. Next area of
> >concentration is the audio section. As we all know, Hallicrafters radios
are
> >very susceptible to failure in the audio section. With no questions
asked,
> >changed out ALL the caps in this area. The cathode resistor had gone up
> >about 300 ohms. This is a MUST change also in allot of radios with any
age.
> >CHANGE THAT CATHODE RESISTOR. When you do change it, put one in that's a
> >little bigger wattage, if possible. I had tested all the tubes. Seeing
they
> >were all logoed Hallicrafters. Most were weak and one had an open
filament.
> >If you have a capacitor checker, make sure to check all the micas and
those
> >double duty disc ceramics. Well, that's about it for yesterday, will be
> >headed back to the shop today to tackle some more areas that need
attention.
> >Before I forget, I don't think I saw a line fuse in this radio.
> >NOTE: Install line fuse when installing new three conductor power cord.
And,
> >one other little tip. When you remove a component, just clip a jumper
wire
> >to where the part was. This saves some head scratching after you come
back
> >from dinner.
> >All have a good weekend.
> >Regards,
> >Gary...WZ1M
> >
> >______________________________________________________________
> >Hallicrafters mailing list
> >Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> >Help: http://mailman.qth.net/mmfaq.html
> >Post: mailto:Hallicrafters at mailman.qth.net
> >----
> >List Administrator: Duane Fischer, W8DBF **for assistance**
> >dfischer at usol.com
> >----
> >Hallicrafters Collectors International: http://www.w9wze.org
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sun, 26 Feb 2006 12:09:29 -0500
> From: carolew <carolew at bellatlantic.net>
> Subject: Re: [Hallicrafters] SX-71 UPDATE
> To: "Oliver J. Dragon" <spress at rcn.com>
> Cc: GBrown <gkbrown at gwi.net>, hallicrafters at mailman.qth.net
> Message-ID: <4401E0C9.AFB23237 at bellatlantic.net>
> Content-Type: text/plain; charset=us-ascii
>
> I agree with Ollie. I love those progress reports, Gary. Your sequence of
repairs
> is a good lesson for us all.
>
> Joe Connor
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sun, 26 Feb 2006 09:26:21 -0800
> From: Edward B Richards <zuu6k at juno.com>
> Subject: [Hallicrafters] WTB: lamp holders
> To: hallicrafters at mailman.qth.net
> Message-ID: <20060226.092621.3924.3.zuu6k at juno.com>
> Content-Type: text/plain; charset=us-ascii
>
> I am looking for 2 (maybe 4) matching lamp holders of the type that mount
> on a front panel and illuminate the meter below. They should be hooded
> except for an opening at the bottom. I have seen them on military gear.
> Thanks.
>
> 73, Ed Richards K6UUZ
> Simi Valley, Ca 93065
> Home of the Air Force 1 pavilion
>
>
> ------------------------------
>
> Message: 5
> Date: Sun, 26 Feb 2006 13:19:50 -0500
> From: "Joe and Ann Vlk" <jvlk at charter.net>
> Subject: [Hallicrafters] HT-37 Sideband Supression
> To: <hallicrafters at mailman.qth.net>
> Message-ID: <004001c63b01$3c16efa0$2f85ec18 at winxphome>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I am still having trouble getting the unwanted sideband on my HT-37
properly supressed.  I inject an audio signal at the mic input and watch the
display on my Icom 756 pro.  I see the unwanted sideband amplitude go down
about 25-30 db on the display as I adjust the HT-37 (HT-37 spec is minus
40db @ 1 kc).  Yet, when I modulate the rig in regular conversation on the
air, the receiving station says my unwanted sideband is only about 2 S units
(12 db ?) lower than my desired sideband.  Any words of advice?  Joe  W8DCQ
>
> ------------------------------
>
> Message: 6
> Date: Sun, 26 Feb 2006 11:57:05 -0700
> From: "Fern Rivard" <crc at cyberlink.bc.ca>
> Subject: [Hallicrafters] re Globe V-10 vfo
> To: <Hallicrafters at mailman.qth.net>
> Message-ID: <009901c63b06$6f8e09e0$6400a8c0 at your03667082de>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
>
> >> Does anyone have any information regarding the Globe V-10 vfo? I
> >> wonder what vintage it was and was tube line up was in it.  Would it
> >> be compatible with the Globe Scout Deluxe transmittter? Also what
> >> would be the approximate value of one of those in excellent condition
> >> please? Were they fairly stable or real drifty?
> >>
> >> Thanks from Fern
> >
>
>
>
> ------------------------------
>
> Message: 7
> Date: Sun, 26 Feb 2006 13:54:10 -0800 (PST)
> From: Glen Zook <gzook at yahoo.com>
> Subject: Re: [Hallicrafters] re Globe V-10 vfo
> To: Fern Rivard <crc at cyberlink.bc.ca>, Hallicrafters at mailman.qth.net
> Message-ID: <20060226215410.7516.qmail at web52905.mail.yahoo.com>
> Content-Type: text/plain; charset=iso-8859-1
>
> The V-10 VFO came out after the WRL 755 / 755A series.
>  They are compatible with the Globe Scout Deluxe.  If
> I remember correctly they are pretty stable.  However,
> like all external VFOs you need to let them run
> continuously when transmitting (definitely do NOT key
> the VFO on CW to avoid chirp).
>
> The 755 and 755A were very stable after warm up.  I
> have a 755 in the re-creation of my first General
> Class station from 1959 and it is definitely stable.
>
> Glen, K9STH
>
>
> --- Fern Rivard <crc at cyberlink.bc.ca> wrote:
>
> Does anyone have any information regarding the Globe
> V-10 vfo? I wonder what vintage it was and was tube
> line up was in it.  Would it be compatible with the
> Globe Scout Deluxe transmittter?
>
>
>
>
>
>
>
> Glen, K9STH
>
> Web sites
>
> http://home.comcast.net/~k9sth
> http://home.comcast.net/~zcomco
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
>
> ------------------------------
>
> Message: 8
> Date: Sun, 26 Feb 2006 20:36:32 -0500
> From: "GBrown" <gkbrown at gwi.net>
> Subject: [Hallicrafters] Head Scratcher
> To: <hallicrafters at mailman.qth.net>
> Message-ID: <008b01c63b3e$3d993620$d5a3c3d8 at computer>
> Content-Type: text/plain; charset="iso-8859-1"
>
> OK, maybe someone has asked this before but here it goes again.
> #1. When Hallicrafters assigned a number to a piece of equipment, why did
> the receiver get designated "S". I assume the "T" ment transmitter.
> #2. This is a hard one. How were the numbers assigned to the different
> equipment. From SX-62 to SX-71 we are missing the ones in between. Were
the
> missing numbers experimental and never made production? Were the numbers
> just a random pick? Were the numbers pulled from a hat?
>     As you can see, I have to much time on my hands, hehehehehe
> Regards,
> Gary...WZ1M
>
>
>
> ------------------------------
>
> Message: 9
> Date: Sun, 26 Feb 2006 19:40:55 -0600
> From: "Mark Shaum" <k9tr at dtnspeed.net>
> Subject: Re: [Hallicrafters] HT-37 Sideband Supression
> To: "Joe and Ann Vlk" <jvlk at charter.net>,
> <hallicrafters at mailman.qth.net>
> Message-ID: <000801c63b3e$e0a21e90$0400a8c0 at xp2500>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> Joe,
>
> I don't have my original notes handy from when I swept an audio generator
> through my HT-37, but I do recall that 20-25 db of unwanted sideband
> suppression was the best I could manage across the entire audio range.  I
> could easily get 40+ db at any single frequency via adjustments, but a
sweep
> generator more closely will show what the exciter will do when voice
> modulated.
>
> And with S meters being they way they are nowadays, 2 S units could mean
> anything from 8 to 20 db depending on the receiver and received strength.
>
> 73! - Mark K9TR
>
> ----- Original Message ----- 
> From: "Joe and Ann Vlk" <jvlk at charter.net>
> Subject: [Hallicrafters] HT-37 Sideband Supression
>
>
> I am still having trouble getting the unwanted sideband on my HT-37
properly
> supressed.  I inject an audio signal at the mic input and watch the
display
> on my Icom 756 pro.  I see the unwanted sideband amplitude go down about
> 25-30 db on the display as I adjust the HT-37 (HT-37 spec is minus 40db @
1
> kc).  Yet, when I modulate the rig in regular conversation on the air, the
> receiving station says my unwanted sideband is only about 2 S units (12 db
> ?) lower than my desired sideband.  Any words of advice?  Joe  W8DCQ
> ______________________________________________________________
>
>
>
> ------------------------------
>
> Message: 10
> Date: Sun, 26 Feb 2006 20:44:57 -0500
> From: Bill Gerhold <k2wh at optonline.net>
> Subject: RE: [Hallicrafters] Head Scratcher
> To: 'GBrown' <gkbrown at gwi.net>, hallicrafters at mailman.qth.net
> Message-ID: <000b01c63b3f$6a925070$8e1ac144 at nlrhv0jzb9hyx7>
> Content-Type: text/plain; charset=us-ascii
>
> Well then, why are tubes called tubes instead of bulbs.
>
> Seriously though, the "S" was used because competing manufacturers were
> already using "R" and Hallicrafters wanted to be distinguished from the
> crowd.
>
> Hallicrafters used "T" for transmitter because it was the logical choice
for
> transmitters because most manufacturers of radio equipment at the time
were
> only making "R"'s or receivers.
>
> Now, if you believe this baloney well I have bridge to sell you. Hi Hi.
>
> K2WH
>
> -----Original Message-----
> From: hallicrafters-bounces at mailman.qth.net
> [mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of GBrown
> Sent: Sunday, February 26, 2006 8:37 PM
> To: hallicrafters at mailman.qth.net
> Subject: [Hallicrafters] Head Scratcher
>
> OK, maybe someone has asked this before but here it goes again.
> #1. When Hallicrafters assigned a number to a piece of equipment, why did
> the receiver get designated "S". I assume the "T" ment transmitter.
> #2. This is a hard one. How were the numbers assigned to the different
> equipment. From SX-62 to SX-71 we are missing the ones in between. Were
the
> missing numbers experimental and never made production? Were the numbers
> just a random pick? Were the numbers pulled from a hat?
>     As you can see, I have to much time on my hands, hehehehehe
> Regards,
> Gary...WZ1M
>
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Hallicrafters at mailman.qth.net
> ----
> List Administrator: Duane Fischer, W8DBF **for assistance**
> dfischer at usol.com
> ----
> Hallicrafters Collectors International: http://www.w9wze.org
>
>
>
>
> ------------------------------
>
> Message: 11
> Date: Sun, 26 Feb 2006 20:46:05 -0500
> From: <amfone at sbcglobal.net>
> Subject: Re: [Hallicrafters] Head Scratcher
> To: "GBrown" <gkbrown at gwi.net>, <hallicrafters at mailman.qth.net>
> Message-ID: <000601c63b3f$93394420$a00c8d46 at x4q6i8>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
>    "S"meant basic selectivity , that is not really meant for
communications
> work, but good overall performance.  SX as in the SX 71 meant excellent
> selectivity and " high end communication" ability for separating close in
> stations from the station you want to listen too. I believe the SX 71 was
> the first to have this designation.
> 73tim
> wb8uhz
> ----- Original Message ----- 
> From: "GBrown" <gkbrown at gwi.net>
> To: <hallicrafters at mailman.qth.net>
> Sent: Sunday, February 26, 2006 8:36 PM
> Subject: [Hallicrafters] Head Scratcher
>
>
> > OK, maybe someone has asked this before but here it goes again.
> > #1. When Hallicrafters assigned a number to a piece of equipment, why
did
> > the receiver get designated "S". I assume the "T" ment transmitter.
> > #2. This is a hard one. How were the numbers assigned to the different
> > equipment. From SX-62 to SX-71 we are missing the ones in between. Were
> > the
> > missing numbers experimental and never made production? Were the numbers
> > just a random pick? Were the numbers pulled from a hat?
> >    As you can see, I have to much time on my hands, hehehehehe
> > Regards,
> > Gary...WZ1M
> >
> > ______________________________________________________________
> > Hallicrafters mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> > Help: http://mailman.qth.net/mmfaq.html
> > Post: mailto:Hallicrafters at mailman.qth.net
> > ----
> > List Administrator: Duane Fischer, W8DBF **for assistance**
> > dfischer at usol.com
> > ----
> > Hallicrafters Collectors International: http://www.w9wze.org
>
>
>
> ------------------------------
>
> ______________________________________________________________
> Hallicrafters mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:Hallicrafters at mailman.qth.net
>
>
> End of Hallicrafters Digest, Vol 25, Issue 39
> *********************************************
>
>
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