Hallicrafters SX-71 Repair & Detailed RF/IF/Crystal Phasing Alignment

[@andybonneau9209]

I had Halicrafters ham radio gear when I first got into it many years ago. Nice to see these old beauties be brought back to life. Excellent job Tony.

[@robertarchuletta2498]

Very informative. Enjoyed this video very much. Who would have ever thought that a spectrum analyzer and a signal generator capable of sweeping would ever be used to tune these old rigs up?

[@i82996]

Nice work. Love the receiver. The accuracy of the dials are off on the higher bands because it is a Hallicrafters. It will never be right on the button after alignment. You are a good instructor. Albert

[@HazeAnderson]

Thank you for these long videos, I am learning so much. 👍

[@johnwaldburger8822]

Great video Tony. Getting ready to restore my SX-71 so this was super helpful. I am sure I will be referring back to it

[@xraytonyb]

Best wishes for your SX-71 project!

[@batterymakermarkii2654]

I had one of those in the mid eighties. Great set to listen on. It was black with yellow lettering--nicotene pickled. When I finished cleaning, it was the familiar dark grey with white lettering, nearly new looking.

[@cuban9splat]

Great job on this old National. Yup, SSB tuning on these older radios can be tricky. But, after doing it for a while you catch on. She is a classic. Thank you for sharing with us. Happy Holidays and I hope you and yours have a great New Year. 73 de K7RMJ Frank

[@jpkellyburbank]

My father brought one of these home back in 1964 and it was what got me started in amateur radio. Thanks for being my way-back machine.

[@tubeDude48]

As always...great explanation & great job on alignment !! It was worth the time... The wasn't a Lindenas hatchet job!!!!

[@Croccydile]

That receiver is almost unbelievably sensitive! I enjoyed watching all almost two hours of this video given the great detail.

[@dhpbear2]

Tony, your videos are NEVER boring! (1:48:12). I agree with you about band-sweeps, however, SW has some exotic stuff!

[@johnnorton6085]

Wow, talk about timing. I'm restoring a Drake R4B and I want to use a spectrum analyzer to align the 50 kHz passband. Thank you for the detailed procedures you used.

[@TheDevice9]

Really interesting video, thanks. This radio is very similar to my Hallicrafters S-76, which I restored early this year... the first and only dual conversion I've ever worked on. I thought mine was the first dual conversion model but the SX-71 looks like it came out a year earlier. Mine doesn't have the crystal filtering and the IF's are 50kc and 1650kc. The 50kc is not available on my signal generator, so I had to get creative on the alignment using a harmonic from an audio frequency tone. I'm sure I could have done it better. I really enjoyed seeing how this kind of thing is done when you have the right equipment and know how. Thanks again.

[@billymoretti8437]

What a wealth of knowledge! thank you for sharing this!

[@thevintageaudiolife]

Thank you for this video, For the past weeks I've been replacing capacitors and all resistor on my National 2-40D. Just finished the IF/RF alignment this morning. The instructions from the manual was straight forward, however the IF cans and capacitors inside the IF cans where full of grim and oils, thus making the alignment a bit of a headache at first. Now my National sounds super, but i mean super sensitive! thanks for this video, i really appreciate it learned new things along the way. Oh by the way, I had to replace all the Mica Mold caps, they measure dead on, but as soon as voltage is applied they drift like crazy!

[@davidhoppe3062]

Awesome!!! So awesome I found one on a auction site and made a offer, yep...offer accepted! Now to finish my Current Limiting Variac and Isolation Transformer! Happy New Year :)

[@tygertyger8597]

Great video Tony. Glad to see this one because a few years ago I rescued one of these SX 71 units from a junk shop. Turns out it is also the one with the 15 meter band and the black face knobs. I'm not sure what I'll do with it but I really appreciate learning more about it. Happy (early) New Year.

[@jdmccorful]

Outstanding!!!! Great instructions on alignments, and the different ways you were doing them. Thanks Tony, always a pleasure, Happy New Year to you and yours.

[@hestheMaster]

Tony you really know your stuff. Hopefully someone will come across this video one day and realize this is the correct procedure after replacing any bad components.

[@cjay2]

Great video - well done, Tony. Didn't think I'd stay for the whole thing, but here we are, even the dial alignment.

[@paulsto6516]

That was a very fun and fascinating video! Thanks for sharing your skills.

[@johnblystone8781]

Thanks Tony! Enjoyed the entire video.

[@Theoobovril]

Great work, Tony, here's to 2022.

[@RandomMichael]

I was having trouble fixing one of these ten or twenty years ago. An almost complete loss of sensitivity at random times. Then after several frustrating days one quiet afternoon on the dining room table, I lifted up the open chassis and turned it upside down to check something underneath. I heard the slightest sliding noise. I tried turning it over and back over again. Again I heard the tiny noise. After more examination I found one of theslugs in one of the IF transformers was broken in half and when turned over it would slide downa half inch or so! I took the transformer apart and glued the pieces together and it worked fine! Very fine in fact.

[@Gordonseries385]

Nice work. Enjoyed watching and taking the time to show us. Merry Christmas and Happy New Year. Take Care!

[@multicyclist]

I really enjoyed this video. A Hallicrafters collector (somewhat). Love these old radios. Thanks for the great video.

[@mnoxman]

Keep in mind that NBFM has become much more narrow since that radio was produced. When this was produced NBFM was 30Khz, in 60s it became 25Khz. As of 2013 NBFM is 12.5khz. All of this is used in Analog Land Mobile Radio (two-way). Not much, other than hams, is using the 30-80 mhz band any more. A few rural states still use the VHF Low band but they are very likely to be gone soon. A old school baby monitor or vintage cordless phone is what you can tune in.

[@xraytonyb]

Thanks a lot for sharing this. I wasn't sure where it was used, if at all anymore. It's interesting to learn about this stuff. The other thing I noticed about this feature on the SX-71 is that it lacked a limiter circuit and used a very basic type of detector. Thanks again!

[@dogbucket]

Great video, as usual I learned some useful stuff. I enjoyed your use of the spectrum analyzer for the crystal filter tuning. Best wishes to you, too, Tony.

[@allthegearnoidea6752]

Great video Tony. I have only worked on a few Hallicrafters but I’m a fan of them.

[@ricke.2205]

Happy New Year to you and your family, Tony!

[@johnbellas490]

Hello Tony! I have a lot of Collins radio gear including the KWS-1 1KW SSB transmitter and the 75A4 receiver of about 1956 vintage and they ALL have the Bristol setscrews so I have that same little blue set you have plus a larger X-Cellite set. I have some Hallicrafters sets too but not the SX-71. Happy New Year there Tony !! 73's from KC2UVN.

[@jim874]

So does the R-390A

[@johnbellas490]

@@jim874 I have the R-390A also! but I have never had any of the knobs off of it yet, so Now I know that radio will need the the Bristol set too, thanks a bunch!!

[@ThinkinThoed]

Love the longer video format, great work! :)

[@maj.d.sasterhikes9884]

Nice old radio. Looks similar to my old National NC-98.

[@jonteske4267]

Functionally NC-98 pretty much the same, but the SX-71 (a teen friend had one in the 1950s when I was first licensed and we used his station for contests) has many finer features such as double conversion - to reduce images - better selectively features etc. Another friend had an NC-98 and that was a quantum leap over what I had for my first receiver (Hallicrafters S-38D.) I was 13 when licensed and finally had to tell my folks the S-38D just wasn't a suitable radio. I got a Hammarlund HQ-100 which was decent but I've learn much over the years. While I have modern gear, I love working on the radios I couldn't possibly have afforded as a young teen. And XrayTonyB this was VERY informative even though I've done much of this myself.

[@sundarAKintelart]

Wish you a Happy and peaceful New year

[@billmcdonald2436]

I love alignments like this. Hopefully someday I will have the equipment and knowledge to do these myself.

[@pd1jdw630]

I skipped trough some theoretical stuff. Cause I’m on the other side of the big pond. But I do love to see these old radios getting there live back. And see them come to live with every turn and twist on a alignment point.

[@arsimahmetaj6272]

Love your work , happy holidays

[@alanc1085]

Great video, congratulations from Brazil.

[@zamankadeem]

Good job i enjoyed this adventure greetings from kuwait.

[@tectalabyss]

Amen, and all the same to you and yours. God bless.

[@EngineeringVignettes]

Being able to slowly sweep through a frequency, on a good sig gen, sounds like an ideal job for a HP 3314A. One reason why I keep a few of these units on standby (in storage). Cheers Tony, merry Xmas and have a good new year.

[@keithbrandaw7229]

I learned today thank you Tony!

[@alanlefevere3678]

Excellent work as always .

[@TheRadioShop]

Very Nice repair Tony. I expected nothing else from you :-). Great job on the demostration of the steps you take to show folks what is going on. .

[@xraytonyb]

Thanks for stopping by, Buddy! Always a pleasure to hear from you!

[@gearheadted9210]

very cool radio and great explanations,really helps a greenhorn out,I have a shelf full of old hallicrafters to go through soon as I get my bk747 tube tester calibrated soon as I get my eico vtvm squared away and calibrated haha,Happy new year,2022 will be awesome~NESARA~

[@rolfts5762]

Just started to watch this beauty "christmas-movie" , two hours :-) ,..time in norway 06.30 am ..Coffee filled up //Thanks in advance for making these videos. Joyful to watch&listen. Always learning something new from your videos.

[@rolfts5762]

(Finished watching) Super video Tony. --And thank you for the greetings you gave to us all --Happy upcoming NewYear to you & your family also.

[@billgreen4919]

Tony, Thanks for explaining what your doing and WHY! Would like to see a schematic or short video on the Isolation module for the Spectrum Analyzer. Could use one myself for those IF with a crystal.

[@zx8401ztv]

Loverly repair and tune tony, it's so alive now :-D

[@towerman75]

Outstanding, really enjoyed, very knowledgeable. Keep up the good work. Jim WA5WRE

[@dbingamon]

Good receivers. I have one, along with the original speaker.

[@steveedwards4868]

i got a hallicrafters sx-99 and it needs a little work but it does work good

[@frankcloskey7789]

Excellent Repairs. 12/28/2021

[@wagnerfratelli3500]

Muito bom ,vivendo e aprendendo sempre...

[@VAD-man]

Thanx m8. Great instructio s.

[@markanderson350]

Really good explanations of alignment with few mistakes. I found so much helpful information. I have an sx 42 to restore and will use much of your advice. Any easy way to find the xtal phase frequency with just an rf sweep generator a freq counter, meter and scope?

[@mackfisher4487]

As much as I love the high-end tube shortwave receivers accurate frequency display was an issue, WWII the aircraft all carried frequency meters so they could calibrate their receivers then net the transmitter to the receiver. The band spread made tuning a station in easier but added to the complication of determining the station's frequency.

[@robertdodge8587]

Very interesting,Bob,M1ECP.

[@vincenzofidanza2539]

I increased sensitivity by using a 6GM6 with a 10k dropping resistor for HV for the 6BA6. Replacing the 6AU6 with a 6AH6, the 6BE6 with a higher gain equivalent tube and replacing some resistor to better use the AVC on the second 6SK7, making smore similar to the first stage

[@xraytonyb]

These are all things I really want to try someday. This unit belongs to a friend and I didn't want the cost of parts, etc. to get too high. Thanks for the suggestions!

[@vincenzofidanza2539]

@@xraytonyb My pleasure tony

[@DE-iv8if]

A happy New Year ! 01:53:00 I had a Radio with a BFO for receiving SSB and I had _to reduce the Sensitivity_ (using manual Gain Control mgc) because from my Experience, _on strong_ Stations / Signals the Sound will _distort_ to much otherwise..

[@jim874]

SSB with a BFO . Turn the RF GAIN ( SENSITIVITY) down. You were running max open on 10. The front end overloads, making the signal distort, so backing off the RF GAIN fixes that. That's why the Product Detector was a vast improvement over the BFO. You didn't have to ride the gain control. Was the glass dial just dirty on the outside? Good video!

[@xraytonyb]

Thanks for the tip. I didn't think to reduce the sensitivity, but that makes perfect sense!

[@jim874]

@@xraytonyb Ask me how I learned that. As a kid, all I could afford was an HR-10 and it had a BFO . One of my best friends was over at my shack and he was using my rig. He automatically reached over and turned down the RF gain as we listened to another guy on SSB. It was like a holy cow moment for me.

[@cathrynm]

Back when USA made the best electronics.

[@watershed44]

Cathryn Mataga *...and when the USA built things to last a long time.*

[@cathrynm]

@@watershed44 It's sad that one of these old US built radio brands didn't survive into the 80's.

[@watershed44]

@@cathrynm Problem was that our gov't allowed cheap imports into our economy without any penalty many times these products were subsidized by the countries gov'ts to undercut US made product prices.

[@hansonsaylor6366]

I have a hollow crafters SX 71 receiver here at the house, that was giving to me last year, I love this thing! But I am having some problems with the VFO knobs, when I turn the knob on the right side of the band selector it turns a little bit. The needle moves a little bit then it sticks, and I tried everything I know to do, I am a general class ham radio operator, my call sign is KN4ISZ. but other than that, I love this radio, I’m just having a little bit of problems with the VFO knob trying to stick the knob doesn’t stick. The knob turns obviously lol but the needle doesn’t move I think I know how to fix it, but I can’t get down there to fix it let me know if you can help

[@Wizardofgosz]

Wait. I read Halicrafters and clicked on it immediately without seeing who the video was from, and just assumed it was from Terry at D Lab!

[@DAVIDGREGORYKERR]

Could be used as a TELEX Receiver where the output drives the Tone Decoder unit.

[@greggaieck4808]

Iam I press with the sound of the Hallicrafters sx 7 on mw and shortwave receiver

[@xraytonyb]

0:15 Intro 6:31 Power supply Test & demo of the OD3 regulator tube 16:00 Trying to receive a signal - a few issues found. 18:05 It's alive! 21:22 Cleaning the rotor on the tuning gang 23:00 Paper caps replaced, ready for another test. Works good, but not great. 27:33 Bristol wrenches used for removing the knobs ARE NOT the same as allen (hex) keys!! 29:28 This radio sounds really good! 30:53 Alignment begins. A few notes about the alignment. 39:02 Connecting the spectrum analyzer to the radio to set up the crystal phasing alignment 44:12 looking at the spectrum of normal, broad crystal and narrow crystal settings and identifying the resonant point of the crystal 47:33 Aligning the crystal at adjustment "U" 52:36 Aligning the IF to the crystal frequency. 1:00:24 Setting the NBFM "null point" for narrow band FM mode 1:06:16 What is NBFM (narrow band frequency modulation) 1:11:45 Aligning the 2.075MHz "second IF" 1:17:29 Testing the receiver after alignment.....unsatisfying results :( 1:18:57 Troubleshooting & repairing the AVC circuit 1:23:42 Testing the receiver after repairing the AVC 1:25:09 Aligning the RF section for dial accuracy 1:44:09 A few final notes... 1:48:06 Testing the finished product and closing thoughts

[@DAVIDGREGORYKERR]

3KHZ NBFM is used on the CB27/81 equipment.

[@DAVIDGREGORYKERR]

What about a new DBM mixer for the first conversion like a Vacuum tube implementation of the SO42P using 4x ECC88 tubes.

[@migueloyarzabal]

How did you make the rotating table, I didn't find it in the videos.

[@MidAtlanticRadioRepair]

Great video Tony!!!! Can you tell us what brand of alignment screwdriver that was with the orange handle? I have a set of blue ceramic screw drivers but they are very short. Thanks my friend

[@xraytonyb]

The alignment screwdriver is made in Japan by a company called Engineer. You can usually find them on eBay and sometimes Amazon, or on their website which I think is www.engineer.jp. They aren't cheap, but they are much more durable than any other ceramic alignment tool I've ever seen. You have to shop around, as I've seen prices all over the place for these, anywhere from $12 up to $30+ for each tool (they have several sizes).

[@christiantreldal1585]

Hi Tony. Tnx for another great video. It would have nice to have had a demo of how selective it is in the cw portion of the 40m band. Are there possibilities for extra filters? Happy New Year to you and yours. 73 de OZ1GNN

[@xraytonyb]

There are a lot of mods out there for these receivers. You can go quite a bit beyond where I went with this unit. As it belonged to one of my friends, I didn't want to go crazy with parts and mods on this particular unit. Maybe someday I'll do another one and we'll do some of the mods. Thanks for watching!

[@scharkalvin]

Added wire for a Q-Multiplier?

[@Homer19521]

Great vid!! Is there a way to find the crystal freq without a SA? I've a Hammarlund HQ180 & want to align it & it has 2 crystals as I recall. Thanx Tony and Happy NY.

[@xraytonyb]

Yes. The service manual explains how. It works best with an analog signal generator, so that you can rotate the frequency knob back and forth (i.e. "rock" the frequency control). Using the BFO to create a "note" anywhere from 400Hz - 1kHz, you monitor the "note" or audio tone at the speaker terminals with a scope as you rock the frequency knob back and forth. At some point, the amplitude of the tone will peak a little bit (your first peak) & then drop sharply. You have to go really slow, as this "dip" is very sharp and you can pass right thorough it if you adjust the frequency too quickly. After you pass though the "dip", the amplitude will begin to go up again until it reaches another peak (your second peak) and then begins to drop again. This "second peak" is the peak of the crystal. Adjustment point "U' will allow you to get the maximum peak for this second peak. This peak frequency will be the frequency at which you adjust all of the other IF adjustments. This will almost always be slightly off of the normal 455kHz IF, but that's OK. Hope that helps.

[@Homer19521]

I think you just told me to buy a SA. ;-) Thank you for the work around. Happy NY, Tony.

[@greggaieck4808]

When I watched Mr Carlson lab he did the lament with the bfo on, 🤔so I think

[@HAUNTED-HAM]

Great video! Where did you get the color schematic?

[@xraytonyb]

I found it online. Someone else (not sure who) did a really nice job on it. If you search "Hallicrafters SX-71 schematic" you should be able to find it.

[@burtfisher7059]

I have this the 2 mhz is missing, where does it originate?

[@mikesradiorepair]

Another way to "loosely" couple to a circuit is to use what they called a gimmick capacitor back in the day. Transceivers back in the day often used gimmick capacitors to sample the output for the RF power meter on the radio. A gimmick capacitor is nothing more than insulated wire. Take a piece of solid conductor insulated wire and cut it in half. Twist the two wires together. On one end of your now twisted together insulated wires strip the wires. Put a alligator clip on one and just leave the other one bare. The two wires are not physically connected to each other, they are insulated by the wire insulation and you end up with a "capacitor" of a couple pF. Basically the wires are the capacitor plates and the insulation is the insulator between the plates. To use it just clip the alligator clip to the circuit you want to probe and attach your test lead to your instrument to the other wire you stripped the insulation off of. Here you did basically the same thing, it's a "gimmick" capacitor.

[@xraytonyb]

So good to hear from you, Mike! That's a great suggestion. Those work really well. They also used those in some of the lower-end radios to couple the BFO into the IF. Thanks again. Hope all is well!

[@MidAtlanticRadioRepair]

Hi Mike, I hope you are well!!

[@jpdesroc]

What is the company/part number of the safety cap you chose ? So you placed it right in parallel with the incoming 120vac ?

[@xraytonyb]

I just used a standard X1/Y2 capacitor rated at .01uF /440 VAC. To test the unit, I just replaced the single cap from one leg of the power cord to chassis. After everything was working, I added a second cap from the other leg to chassis (for a "y" filter) and a third (which should be a bit higher value, .02 - .047 uF range) across the line ("X" filter).

[@jpdesroc]

@@xraytonyb Thanks for your reply !

[@WrankledEngine]

My SX-71 is missing the S-Meter. Does anybody here have an SX 71 parts chassis with a meter they would sell?

[@twoheart7813]

I know where one is in an old polebarn under a tarp , has a broken fine tuning dial string, could have it for free if I had the space, which I don't.

[@karlgoebeler1500]

Merry Xmas everyone

[@srtamplification]

Hey Tony, what kind of antenna would be best to use with one of these units?

[@xraytonyb]

These old radios work great with a simple long-wire antenna. Now if you plan on using a transmitter, that's a different kettle of fish ;)

[@David-gw2lv]

A long wire.

[@andybonneau9209]

The lower the frequency, the longer the wire. Calculators available online. Best to keep it well off the ground if you can.

[@DAVIDGREGORYKERR]

This receiver could have be made very portable if they had used the low voltage vacuum tubes designed in 1957 and used 2x 2N2955 output transistors for the power output stage and run off 2xPP9 9V batteries and would be a lot lighter due to the fact that the heavy power transformer is not required.

[@greggaieck4808]

Xraytonyb your frands Hallicrafters sx 7 shortwave receiver is cool

[@DAVIDGREGORYKERR]

Someone has gutted one of these radios and rebuilt it using solid state parts and I thought he would would have used two SO42P DBM units which include an oscillator and MC1350 as the IF stages but he didn't.

[@harbselectronicslab3551]

Those set screws are also known as Torx drivers.....the Male version is Torx drivers and the Female (sockets) are called eTorx sockets.

[@xraytonyb]

I think the bristol spline drivers are slightly different than the torx, as they have sharper flutes. I have tiny torx drivers and they don't seem to fit the screws properly. I shoul compare them someday. Thanks for the comment!

[@materialsguy2002]

Hi Tony: Great video btw, thanks for taking the time. You are correct, Bristol predates Torx by nearly 50 years. Although they are similar, they should not be interchanged either from the fastener side or the driver side. The R390 series of receivers famously made use of Bristol fasteners, many of which have been ruined by the use of Torx or (even worse) hex drivers.

[@K7MD]

Sooo, my SX-71, along with other radios, came stock with Bristol Splines. At this point they’re mostly still spline, but many are ‘damaged’ and only a hex or Allen wrench can remove them. Question, where is a good source for replacement grub screws for them?

[@bobvecchi7981]

The wrenches used on the knobs would be torx wrenches, not spline wrenches. The configuration of a spline wrench is different.

[@ErwinSerle]

1:25 do not kill your Voltmeter with the volume up ;-)

[@samjones1954]

By the time you replace all the caps and replace any bad tubes, you might be further ahead to buy a brand new receiver.