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Dirk van der Berg
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Post subject: Hallicrafters sx71 - will it be worth it ? Posted: May Fri 04, 2012 5:08 pm |
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Joined: Feb Sun 07, 2010 6:04 pm Posts: 106 Location: South Africa
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I received this sx71 is this condition BUT will it be worth it ? Will have to hunt for front panel ...  wonder if someone out their could put me in the right direction ?  Looks like all the knobs is on . Will have to install mains transformer - I think somewhere i might have sx42 mains transformer ...will check voltages  Your thoughts please Dirk
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rsingl
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Fri 04, 2012 5:40 pm |
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Joined: Jun Sun 19, 2011 2:31 pm Posts: 905
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Your SX-71 is a later production version because the 15 meter band appears on the band spread side of the dial.
The SX-71 is a competent receiver and their first double conversion design with a 455 Khz. second IF. The S-76 came out a short time later and was also double conversion but was the first of the Hallicrafters to use a 50 Khz. final IF and that became the Hallicrafters standard with the SX-88, 96, 100, 101, 115 and 117 receivers. The SX-71 relies upon a crystal filter for most of its selectivity capability while the later receivers benefited from the very nice selectivity from the low final IF.
The SX-71 is a decent general coverage receiver and is usable for amateur radio operation. Since you need a front panel you are probably looking for a parts unit in good shape and it is likely the parts unit may be cleaner than what you have now. If the parts unit is an earlier run, you might want to transfer your dial scale over to it.
Whether it is worth repairing will have to be decided in terms of how much fun you have restoring gear. The SX-71 was sold in large numbers and it was a decent receiver but nothing extra special. It was the first of the Hallicrafters dual conversion receivers and few of the double conversion Hallicrafters used a 455 Khz. final IF; the SX-73 comes to mind and there may have a few other models but Halli settled on using a very low frequency final IF. It will also receive NBFM which was marketed heavily by Hallicrafters as a means for amateurs to avoid BCI (broadcast interference) but TVI quickly made BCI relatively less important and NBFM for HF use never caught on. I have a HT-18 VFO and HT-19 transmitter, both with built in NBFM , but those were short run items, I don't think the HT-19 really made it into full production. My HT-19 came with the original 4 pages of instructions and open binding posts on the back which are hot with 1,500 volts; these posts allowed the use of an external modulator for AM but there should have been a cover on them.
Rodger WQ9E
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Ed Engelken
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Fri 04, 2012 6:48 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 1070 Location: Canyon Lake, TX
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It looks like the power transformer is missing. That will add the to the cost of restoration unless you can pick up a junker SX-71 to obtain the front panel and cabinet that also has a good power transformer.
_________________ http://www.tarc.gvtcwebspace.net
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tubeR
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Fri 04, 2012 7:34 pm |
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Joined: May Wed 06, 2009 7:01 pm Posts: 477
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Hi Dirk, It appears you following a couple of my bad habits. Picking up basket case projects such as this and this  If so you will need this:  Here's the story on my completed SX-71. http://www.ohio.edu/people/postr/bapix/SX71.htmThe same fellow I bought my SX-71 from and to whom I gave a small stack of 30s QSTs (duplicates) saw me at the next hamfest and passed a faceless parts-donor SX-71 to me insisting I take it. I insisted on some minor remuneration back to him. The following hamfest, he brought this SX-71 face. Don't know what the shipping to U of SA will be but I doubt the panel will be damaged in shipping. It's a tough piece of metal. Sorry, transformer needed here but then I believe you need a 50 Hz 240 volter anyway. Send me your address and I'll see what the US PO will charge. Remuneration? Hey it's worth its weight in Krugerrands.  No? Well then stick some extra for me in your church collection plate. Cheers, -- Rich
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Dirk van der Berg
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Sat 05, 2012 7:27 am |
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Joined: Feb Sun 07, 2010 6:04 pm Posts: 106 Location: South Africa
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Thank you for all the info Rodger , luckily the chassis (underneath) is quite "clean" so the previous owner spared me any surprices Now tubeR ( Rich) ! This will be excellent if i could get hold of front panel all the from USA ? Will i have a story to tell years from now re: this sx71  I have installed some exstra lightning to try and avoid "Multiplying" of my radios in my shack / radio room at night  . Where can i get hold of your email adress please Rich ? Regards Dirk / zs1vdb Email: zs1vdb@hotmail.com
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Ancient_Hacker
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Sat 05, 2012 1:56 pm |
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Joined: May Sat 22, 2010 4:42 pm Posts: 2424
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You might be able to find a panel for it. I used to have a rather rare GE console chassis, but no case. Two years later at a garage sale, I stumbled onto a matching console case, with no chassis. Put them back together. Bliss.
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Burnt Fingers
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Sat 05, 2012 5:10 pm |
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Joined: Oct Sat 20, 2007 3:36 am Posts: 13596 Location: New Hampshire
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Quote: Your SX-71 is a later production version because the 15 meter band appears on the band spread side of the dial. It is a Run 4, the final production and it was and looks like 15M was a jammed in afterthought. Since 15M was approved years before actually being released Halli could have designed the radio with it at the begining and provided a full width bandspread. Its a worthwhie receiver to restore just for the high image rejection of the double conversion which will be a big help for the frequencies above about 12-14 MHz. Just dont expect much on 6M. Carl
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Dirk van der Berg
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: May Sun 06, 2012 4:27 pm |
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Joined: Feb Sun 07, 2010 6:04 pm Posts: 106 Location: South Africa
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After replacing power supply transformer and electrolytics  switched on and heard stations all over ..  Some valves was changed before - 6SK7 with miniture valve and 6SC7 with 6SN7  The cabinet has seen beter days , will soon start on respray project .. Best wishes Dirk
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radioterry
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: Jun Tue 12, 2012 12:55 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 1872 Location: Central VA
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Dirk:
I recently picked up an SX-71 Run 4 off of Craigslist. It was in pretty bad shape both chassis and cabinet-wise. It looked like someone had it stowed in their shack near the beach/ocean...lots of rust and "interesting" patina.
I recapped and aligned it and then removed the rust and repainted the cabinet. I was somewhat surprised at both it's sensitivity and selectivity!
BR,
Terry
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Dirk van der Berg
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: Jun Wed 20, 2012 6:02 pm |
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Joined: Feb Sun 07, 2010 6:04 pm Posts: 106 Location: South Africa
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Thanks to Rich , the frontpanel arrived here in S.A  and will start soon to complete the restoration job ....I heard their is a S53 on its way  Terry , i was surprised how well the SX71 works just on "short" piece of wire about 6meters above ground . Regards Dirk
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morseguy
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: Jun Wed 27, 2012 1:14 am |
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Joined: Aug Mon 28, 2006 3:07 am Posts: 994 Location: Boston area
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I too have an SX-71 that I'm rehabbing, a late model I believe. Check my thread on it. I have recapped and replaced out of spec. resistors. I can't figure why the S meter won't work. Meter seems fine. A resistor (can't remember of hand which one) keeps burning up. Have you done anything more than cleaning to that front panel. Mine looked rough like yours and I did not to go through the bother of sanding, repainting and trying to re-letter it. Silk screening is very expensive so that was out of the question. So I cleaned it very carefully soaked it in a solution of warm water and plain dawn dish detergent. Rubbed it gently with a soft cloth and rinsed it well. Let it dry overnight and do the same again. Let it dry for 24 hours and make sure there is no lint. I then applied about 5 coats of Krylon satin clear coat (TEST FIRST ON A VERY SMALL AREA). What that did make slight scratches almost disappear and larger ones lessen. Plus it gave it a "fresher" look. I clear coat should also help protect the lettering. I'll try to put an after pic up on my sx71 thread to show you.
Dave
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uxnjhdj
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Post subject: Re: Hallicrafters sx71 - will it be worth it ? Posted: Jun Thu 28, 2012 7:08 am |
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Joined: Jun Thu 28, 2012 7:03 am Posts: 1
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It looks like the power transformer is missing. That will add the to the cost of restoration unless you can pick up a junker SX-71 to obtain the front panel and cabinet that also has a good power transformer.
_________________ Lunettes Ray Ban
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