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AMfone's Online AM Handbook => Receivers => Topic started by: wa2pjp on July 05, 2018, 02:56:40 PM

Title: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 02:56:40 PM
I thought I might share the story about the SX-88 I acquired last year from the second owner as a project. It was S/N 294 Run 2 and was pretty dirty, neglected, rotted line cord, just what you would expect from a piece of gear sitting in a basement for 30 years. The pictures below show the radio as I got it before I had done any work to it. The receive sat in the owner's basement on a shelf for about 30 years because it had failed and no one was able to repair. The owner said he had given it to several different techs to trouble shoot the problem, but  no one was able to find the problem and repair it, so since I was looking for an 88 again, I thought I would take a chance and purchase it. Looking at the bottom of the chassis, there were several of the molded paper caps cut out (bumble bee caps), wires unsoldered and loose hardware, I guess from techs that thought that's the way to trouble shoot a problem........ The first pictures show the front panel and who ever removed and replace the panel (one of the techs that worked on it), wired the switches wrong and his fix was to put tape over the panel markings and write on it rather than wire the switch correctly..... the last picture is of course with the panel removed and you can see the condition of the chassis. I have owned several 88's in the past and just moved them on because I was never impressed with their performance. 

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:02:57 PM
The next pictures show the dismantling of the chassis and the second IF chassis that was mounted to the top of the main chassis.....anyone who is familiar with the 88 knows that the second IF chassis is very difficult to remove since all the wiring runs down through the main chassis and is wired to various parts of the radio. The problem that plagued this radio was a burned open resistor under the second IF chassis that was bypassed with a molded paper cap (bumble bee cap) that had very high leakage current to ground. Since none of the techs that worked on this radio was willing to remove that chassis, the poor guy who owned this radio never got very much use of it. The first two pictures show the bottom of the second IF chassis and the last pictures is after I had finished replacing all the parts and wiring. I checked the two crystal frequencies and found that both crystals were way off freq. so I order two new ones to replace the old ones. Bench checking the oscillator showed to be only a few cycles off spec.

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:09:30 PM
After stripping all the parts off the main chassis I had sent it out along with brackets, gussets and shafts to be replated at the chrome plating shop.  The first pics are of the chassis after all the tube sockets and terminal strips were removed Also, the last picture is of the harness before I removed wires that were cut too short and force to fit or reach a tube socket or terminal strip. One of the leads in the harness was cut so short that the terminal strip it was connected to was bent way over just to make the connection.....JUST POOR craftsmanship.

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:14:59 PM
Here is the chassis back from the plating shop in the first picture and the underside after I installed all new tube sockets and terminal strips. On the tops sidethe IF cans remounted. Most of the tube sockets just had poor pin tension and the terminal strips were just over heated and I found on one of the strip, large solder blobs had dripped down though the eyelets and came with in mils of shorting to the chassis.....again just poor craftsmanship and I guess the QC department was on break. 

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:20:41 PM
Here is the underside of the chassis with the harness reinstalled and most of the chassis components installed. I replace every resistor and cap with new ones and replaced the wiring in the harness that was cut short at the factory.  The third and second pictures is of the RF sections and band switch which I completely dismantled to get to components that were located under the switch such as the molded papers and burned resistors and to also clean the switch contacts properly. 

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:24:38 PM
The selectivity switch also had to be completely dismantled and all components replace, contacts cleaned and the detent taken apart, old grease cleaned and a new ball bearing installed. The main and band spread tuning were taken apart for cleaning and new bearings installed because the old bearing had rust on them in the last picture.

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:31:26 PM
The main tuning and band spread caps were reinstalled on the chassis. The main tuning gear assembly did not feel good and was sticking and just was not smooth. the whole unit was cleaned dismantled and new bearing installed, all the bearing races were polished reassembled and all the gear lash was reset. Now the tuning was very smooth and nice feeling then reinstalled on the chassis. All new exact replacement toggle switches were installed because the old ones were intermittent, dull and just worn. None of the old hardware was reused, all the self tapping screws and corroded hardware were replaced with brand new stainless machine screw, many holes re-tapped for either 6-32 or 8-32 machine screws. Also, Hallicraftes had a habit of soldering grounds to the chassis, I used solder lugs attached to tube sockets mounting screws and because of the way the factory did some of the grounding, the lead lengths were just too long, so I rearranged the grounding by adding additional solder lugs to keep all leads short as possible.  A newly repainted front panel was mounted to the chassis and mechanical alignment set so all shafts moved freely. The power transformer was sent out for rewind for the new primary voltage of 120 VAC then remounted.

Title: Re: Hallicrafters SX-88 RUN 3
Post by: wa2pjp on July 05, 2018, 03:41:54 PM
The completed receiver in it's new repainted cabinet and next to my J-500 for on the air testing. the last picture showing some of the old parts removed from the radio. I ran through a very careful alignment and found that it pretty much met specs which the other 88's did not. Everyone of the molded paper caps had checked bad with very high leakage current on a my Sprague Tel-ohmike cap checker and were also way off value. In fact, I thought that since all the caps were reading bad, my Tel-Ohmike, I had a problem with my cap checker.....which I did not, just after 60 years the component were all failing. Most of the resistors I checked were also out of tolerance. The other 88s I owned in the past were all original and performed poorly, maybe most of the components in those radios were also failing.........Since this was such a complete rebuild.......basically I built a new receiver, I'm calling this the RUN "3".

Title: Re: Hallicrafters SX-88 RUN 3
Post by: KD6VXI on July 05, 2018, 07:40:55 PM
That is a really clean restoration.  I wish mine came out as nice cosmetically.

Great job, gave me a bit of inspiration to tackle this Johnson V2 I've had sitting for years.

Kudos, bud.


Title: Re: Hallicrafters SX-88 RUN 3
Post by: w3jn on July 05, 2018, 08:38:10 PM
Beautiful 100-point restoration, Joe.  Thanks for sharing!

Title: Re: Hallicrafters SX-88 RUN 3
Post by: K1JJ on July 05, 2018, 11:25:47 PM
Absolutely amazing job, Joe! My jaw dropped. 

Looks like the perfect companion to an HT-32.  Chrome plated chassis,  new wiring, new switches, new tube sockets, smooth mechanical tuning, panel restored, etc... wow.

I'll bet you have a few hundred hours into that. The old saying, "If ya want something done, give it to a busy man"  applies here.

Some of your other projects are no less impressive - the Collins tube audio board restorations, the many Heathkit  projects, your homebrew 813 rig, vintage cars, motorcycles....  You could easily make a great living restoring stuff in the same class as master Howard Mills.



Title: Re: Hallicrafters SX-88 RUN 3
Post by: WA2TTP Steve on July 06, 2018, 02:32:15 AM
Fantastic! A work of art.

Title: Re: Hallicrafters SX-88 RUN 3
Post by: K1ETP on July 07, 2018, 10:16:58 AM
Outstanding job, Joe. Have you compiled the hours spent on the project?


Title: Re: Hallicrafters SX-88 RUN 3
Post by: KL7OF on July 07, 2018, 10:40:58 AM
very nice Joe...

Title: Re: Hallicrafters SX-88 RUN 3
Post by: KB2WIG on July 07, 2018, 12:02:09 PM

Nice work.


Title: Re: Hallicrafters SX-88 RUN 3
Post by: W2PFY on July 07, 2018, 02:58:40 PM
Great job Joe! Joe has been keeping me updated on his progress on this SX-88. He explained to me the very laborious
methods of cleaning the "bread slicers" and it all comes down to sweat equity big time! I wonder how many hours do you think it took you to do all this fine work Joe?

There are not a lot of people like you in radio Joe, and for that you deserve a hardy wheel barrel full of Congratulations For a Job Well Done!


Title: Re: Hallicrafters SX-88 RUN 3
Post by: WBear2GCR on July 08, 2018, 09:38:09 AM

Curious about a few things.

How were you able to paint and create a silkscreen for the front panel??
The bezel, was the original crackle?

And, if you have a good example of the SX-28, how do they compare, side by side?
(They seem similar in several regards...)


Title: Re: Hallicrafters SX-88 RUN 3
Post by: WA2SQQ on July 10, 2018, 09:52:55 AM
I'm really impressed and that does not happen that often. Just curious, how much did it cost you to have the chassis replated and how many hours did you spend on  this project?
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