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 Post subject: Hallicrafters S-11 project
PostPosted: Sep Tue 22, 2020 5:59 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 1740
Location: Peekskill, NY
As promised, here are a few photos of my new winter project - I thought it would be an SX-11 as it has the crystal, but apparently they all did, so it's really just an S-11.

It's been vacuumed out in these photos.


Attachments:
sx_11_1.jpg
sx_11_1.jpg [ 234.7 KiB | Viewed 1997 times ]
sx_11_2.JPG
sx_11_2.JPG [ 294.24 KiB | Viewed 1997 times ]
sx_11_3.JPG
sx_11_3.JPG [ 478.46 KiB | Viewed 1997 times ]
sx_11_4.JPG
sx_11_4.JPG [ 437.48 KiB | Viewed 1997 times ]
sx_11_5.JPG
sx_11_5.JPG [ 343.56 KiB | Viewed 1997 times ]
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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Wed 23, 2020 9:30 pm 
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Joined: Jun Mon 08, 2020 11:29 pm
Posts: 35
Location: Pittsburg, Kansas
Yikes, that chassis looks rough. But, I love the fact that it has an eye tube! Good luck with your winter project.

Cheers
Brian


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Wed 23, 2020 9:51 pm 
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Location: Sanford Fla 32771 (USA)
That looks like a complete teardown to bare chassis, sandblast (or bead/walnut shell) and prime/paint with appropriate color to match original look.
It looks like a radio that is worth the effort.
Keep us posted on the progress.
Do you have the tubes ?
.
EDIT: I see new parts under the chassis, has this been brought up to working condition ? Was there another thread on this radio that I missed ?

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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Thu 24, 2020 2:52 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
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Location: Peekskill, NY
The former owner (Craig) started a re-cap job on the set.

I have about half the tubes now. Still needed, a couple of 6K8s and a 6R5. I am re-basing a 5U4 to look like the 5Z3 rectifier. I could change the socket but that seems wrong....

The front panel actually is brass, and the lettering while worn is original. I am going to try to bring it up to operating condition before doing any cosmetics. Right now the front panel knobs need to be removed to get further into it. One came loose after repeated Kroil applications but there are four others that will probably need to be drilled out - I am working on the drill fixture for that.

The main tuning dial is in excellent condtion, but the bandspread one is pretty warped. I will have to come out obviously but I am afraid it will come to pieces if anything is done to it.

Will post photos of the setscrew drilling when I get to it.

Jim


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Thu 24, 2020 3:34 pm 
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Location: Sanford Fla 32771 (USA)
I don't know why, but I find this radio really interesting. I think that this will be my next project radio, if I can find one reasonably priced.
I see it does not have built in speaker, but nice PP output stage. On the attached schematic where I have circled it
shows 500 and 5000, are these the audio output impedance for external speaker, and are those circles jacks, or terminals on the back ?


Attachments:
S-11_001.png
S-11_001.png [ 158.63 KiB | Viewed 1924 times ]

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Last edited by pauls.ironhorse on Sep Thu 24, 2020 3:56 pm, edited 1 time in total.
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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Thu 24, 2020 3:43 pm 
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Location: Sanford Fla 32771 (USA)
jim rozen wrote:
I have about half the tubes now. Still needed, a couple of 6K8s and a 6R5. I am re-basing a 5U4 to look like the 5Z3 rectifier. I could change the socket but that seems wrong....



I will have to come out obviously but I am afraid

Jim

No need to be afraid. :mrgreen: Oh how a little editing can really change the meaning, I should be in the MSN or politics.
I know the "I" was meant to be "It", but I couldn't resist, sorry.
.
I do not see those tubes on the schematic, so wondering ???
I like the idea of re-basing to leave wiring the same as original.
.
I already have a S-38C (restored) and SkyBuddy S-19 (unrestored).

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https://paulsironhorse.smugmug.com/


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Thu 24, 2020 6:44 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
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Location: Peekskill, NY
Darn keyboard.

Anyway the tubes are 6R7 and 6K7. The 6R7 is the diode/triode detector/1st audio, and the 6K7s, are well, almost everything else. The speaker terminals are just screw-type connections (insulated with phenolic) on the back panel.


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Fri 25, 2020 2:32 am 
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Location: Dallas,TX
Jim,

The SX-11 has the crystal filter while the S-11 does not. I have owned both over the years. When I finally found a nice condition SX-11 I traded off the S-11. I love Hallicrafters radios and magic eye tubes so the SX-11 is one of my favorite receivers. Good luck with your restoration.

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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Fri 25, 2020 6:51 am 
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Location: Fenton, MI 48430
I would glass bead blast the top of chassis.

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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Fri 25, 2020 3:30 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 1740
Location: Peekskill, NY
Cosmetic restoration of the chassis (obviously in desperate need, glass beading would be a nice touch) is a *long* way away. Right now I almost have the drill fixtures done to remove the knob setscrews, which are pretty well locked in place. Photos as the job gets done to follow.....

Interestingly, both the BAMA and Nostalgia Air schematics are listed as "S-11" but both show an SX-11, with the crystal. They suggest the crystal be "put into an external oscillator" to do the IF alignment!


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Fri 25, 2020 9:24 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
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Location: Peekskill, NY
There will be a brief delay. Evidently, hallicrafters used knobs that have heat-treated setcrews. They're not quite glass hard but a file will not mark them. Three flute solid carbide drills on order.


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 5:01 am 
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Joined: Dec Sat 21, 2013 5:15 am
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Location: Puyallup, WA 98371
jim rozen wrote:
I am re-basing a 5U4 to look like the 5Z3 rectifier. I could change the socket but that seems wrong....


Just curious- why aren't you putting a 5Z3 back in it?

Dale


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 1:01 pm 
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I like the styling of the early Hallicrafters sets, I have a number of the earlier models.

In these sets, the only difference between the S and SX is whether it has the optional crystal which could be added at any time. Hallicrafters was trying to meet a minimum price point and making it available without the crystal element allowed a broader market. To change an S to the SX just required plugging in the crystal and aligning the IF to the exact frequency of the crystal used.

Putting the crystal in an external oscillator circuit for alignment really wasn't a great idea because the frequency will shift slightly in various oscillator circuits versus the in-receiver filter circuit HOWEVER the IF chain in these is so broad without the crystal filter in operation that it isn't that critical. However the traditional alignment procedure of getting the IF close to the marked crystal frequency before doing a second touch up alignment after finding the exact frequency in the receiver works fine.

In photos: Hallicrafters SX-9 and SX-11, S-8 prior to restoration (note wooden knobs on these early sets), SX-10 "Ultra Skyrider" for the higher bands (covers 5.5-79 Mhz).

Rodger WQ9E


Attachments:
Hallicrafters.jpg
Hallicrafters.jpg [ 1.03 MiB | Viewed 1763 times ]
Hallicrafters S-8.JPG
Hallicrafters S-8.JPG [ 692.03 KiB | Viewed 1763 times ]
SX-10.jpg
SX-10.jpg [ 423.28 KiB | Viewed 1763 times ]
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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 3:02 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 1740
Location: Peekskill, NY
Very sweet sets there. Mine as mentioned is really an SX, and the instructions do indeed say to use the the Xtal in a "external oscillator." I think I'll do it the other way when it comes around to that. Might be a while at this rate however...

The simple reason for not using a 5Z3 is, I didn't have one! And I have a lot of 5U4s, the only difference according to the RCA receiving tube manual, is the base. So I re-based what I did have.

(The SX-10, has the Lamb noise limiter?)


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 5:18 pm 
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Jim,

It is at least a variation of the Lamb type silencer. the SX-10 has a 1600 Khz IF to provide a little better image rejection given its higher frequency coverage.

National also used a higher IF frequency (1560 Khz) in their rather odd NC-80X and NC-81X receivers which had the mechanical complexity of the sliding coil catacomb introduced with the NC-100 but in these economy models there is no RF stage so the higher IF is needed for sufficient image rejection. These National sets have three IF stages to make up for the lack of RF stage gain. Building them as transformerless AC/DC sets also helped offset the cost of the sliding coil catacomb system.

I have this National general coverage and ham band receiver pair and they are usable but the cost of building them with the mechanically complex coil catacomb would have been better spent on a traditional RF stage design. The National sets have a crystal filter standard which is always in circuit and this was needed for any type of shortwave communications set with this single higher IF setup and National claims variable IF bandwidth from 300 cycles to 7 Khz but they wouldn't want to brag about the shape factor.

Rodger WQ9E


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 6:10 pm 
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Location: Seattle WA US
<<< Error - we seem to have hijacked the thread to S-10 discussions ! Sorry. >>>

That is indeed a Lamb noise blanker in the S-10. The 6J7 noise IF amplifier drives a full wave detector that uses both of the diodes on the Lower 6R7 with an unmarked L (and C21, C18) filtering the blanking signal sent back to the #3 grid of the 6L7 second IF.
Strangely, the well filtered cathode bias developed by the noise amp appears to be fed, via an unmarked bias cell and R32, to set the grid bias on the (lower) 6R7 triode first audio amp. (A feed-forward AGC ??)

Meanwhile the AM detection is performed by the two paralleled diodes on the other (upper) 6R7 which also acts as BFO.

The draftsman who prepared that schematic did us no favors......

-Chuck K7MCG

<edit> Looking at the upper 6R7 - does that common cathode resistor shared by the diode AM detector and the BFO result in it acting as a product detector when the BFO is turned on ?


Last edited by K7MCG on Sep Sat 26, 2020 10:28 pm, edited 3 times in total.

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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Sat 26, 2020 6:12 pm 
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Location: Sanford Fla 32771 (USA)
1) The SX-11 has a crystal in series with the IF (465Khz ?). I assume the crystal gives a very narrow bandwidth allowing for better selectivity, is this correct ?
2) I am guessing the xtal is cut for 465 Khz, but is it special design for IF ?
2) What is the bandwidth of the IF when xtal selected ?
3) When is it best used, AM, SSB, CW ?, or all three ?
Thanks for your answers as I have never used a receiver like this with xtal IF.

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https://paulsironhorse.smugmug.com/


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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Mon 28, 2020 4:23 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
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Location: Peekskill, NY
The setscrew saga.

Shown is a sketch used to make a fixture to drill the locked-up setscrews on the front panel black knobs for that SX-11.
Also shown is the actual fixture, and a sketch of how it was aligned with the setscrew on the knob itself. I used the backside
of a drill to line it up with the hole in the plastic part of the knob, which is larger than the setscrew itself by a good amount.


Attachments:
knob_fixture_dwg.JPG
knob_fixture_dwg.JPG [ 218.7 KiB | Viewed 1636 times ]
knob_fixture.JPG
knob_fixture.JPG [ 188.95 KiB | Viewed 1636 times ]
fixture_alignment.JPG
fixture_alignment.JPG [ 213.58 KiB | Viewed 1636 times ]
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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Mon 28, 2020 4:30 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 1740
Location: Peekskill, NY
Best laid plans: fail - it turns out that hallicrafters, in 1936, used knobs with hardened steel setscrews. So hard they cannot be marked with a file.
So the first try at drilling one out resulted in a dulled no. 31 high speed steel drill. I upped the game by purchasing carbide drills from McMaster Carr,
which were delivered the *next* *day* after I ordered them.

These worked a treat, ate up the setscrew quite easily. Next photo is the hole in the knob where the setscrew used to be.

I thought the knob would then slip right off the shaft. Again, wrong. The steel shafts were badly rusted inside the brass insert, and I needed to
use hammer-head pry bars to extract the knobs. (one control, the tone control, actually was on so tight, it extracted the shaft out of the potentiometer).

The good news is I was able to save, clean, and re-tap all the knobs.


Attachments:
carbide.JPG
carbide.JPG [ 214.89 KiB | Viewed 1635 times ]
drilling_out.JPG
drilling_out.JPG [ 293.69 KiB | Viewed 1635 times ]
screw_gone.JPG
screw_gone.JPG [ 245.99 KiB | Viewed 1635 times ]
extracted.JPG
extracted.JPG [ 267.77 KiB | Viewed 1635 times ]
knob_saved.JPG
knob_saved.JPG [ 268.38 KiB | Viewed 1635 times ]
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 Post subject: Re: Hallicrafters S-11 project
PostPosted: Sep Mon 28, 2020 4:34 pm 
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Joined: Mar Wed 16, 2011 10:44 pm
Posts: 1740
Location: Peekskill, NY
All the black knobs are now off the front of the set - although I had to make an extension for the drill to get to the larger on in the center of the panel.
I was especially worried about the one on the bandspread shaft as I did not want to damage the band switch, but that one came off OK.

The bad news is, the main tuning dial has *three* setscews in it and they are all locked in tight. So more drilling work to do.


Attachments:
drill_extension.JPG
drill_extension.JPG [ 123.05 KiB | Viewed 1635 times ]
knobs_gone.JPG
knobs_gone.JPG [ 125.71 KiB | Viewed 1635 times ]
another_extracted.JPG
another_extracted.JPG [ 263.21 KiB | Viewed 1635 times ]
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