SX-101A

[WA1HZK]

Anybody got the mods written down on this rcvr. yet?
Keith

[w3jn]

Keith, it's been too damn hot to work in the garage... I'll shoot them off as soon as I get it figured out (again).

[wn5t]

I just picked up an SX-101A in need of TLC at the 2006 Russellville, AR hamfest.  Actually, I got an SX-101A and an HT-32A for $35...I didn't have room or desire for the very poor condx HT-32A, so I sent it home with WD5BZO for parts...I guess that makes my SX-101A cost $35!!! 

Anywho, was just wondering about the status of the mod write up...while I vacuum the acorn hulls out of the RX...yes...ACORN hulls...    

73,
Michael
WN5T

[The Slab Bacon]

John has'nt got to penning down the whole shebang, but I can tell you what I did to mine, and it works quite well. Mine is an SX101-A

1. Change C-100 from .001 to .047.
2. Remove C-102
3. Remove C-80 This stops most of the clipping on strong mod peaks and                  Dramatically improves the am auidio quality but makes the ANL totally inoperative.
It is worth doing as it is the one dramatic improvement. I changed the ANL switch from a single pole to a double pole and switch it back in when the ANL is turned on.
If you do the switch deal, you may want to experiment with the value of the cap.
4. Change the audio outpoot transformer to any good single ended transformer rated at somewhere around 5w. Mine wouldnt pass any audio below 300Hz.
5. Change the audio outpoot tube from a 6K6 to a 6V6.
6. (optional) you may want to experiment with stagger tuning the IF's to stretch their bandwith a little.
7. (optional) You may also want to clip out C-94 for a few more highs.

This is what i have done to mine and it has nice rich audio with nice bottom end and warmth. It is still lacking on highs a little due to it's tight IF's, but is VERY plesant to listen too. It is one of if not my favorite receiver.

Trying to trace the audio path on the skizmatic is somewhat difficult due to their portrayal of all of the wafer switches. John (JN) has found a way to jump a couple of the wafers to eliminate the last of the distortion due to the detected audio being still passed through the product detector while in the AM mode. I have not done this to mine and dont know if it is really necessary as mine has a really nice smooth sound to it as it is now and sounds real nice playing through my 12" 3 way speaker system.

                                                                    The Slab Bacon

[wn5t]

Thanks, Bacon... 

I have a  couple of full-BW rcvrs and find them to be...not very useful in the mornings when I'm usually listening on 3.890...unless David (WD5BZO) in Little Rock fires up Big Bertha or the FAT LADY to run off adjancent SSBers...   I'm hoping that this RX and the NC-98 will give me enough selectivity to enjoy what I'm hearing but still sound better than the R-4B.   If nothing else, it will look cool on the desk with the R-46B spkr.

I'll be taking digital photos as I do the refit/restore job so I can post them about...

73,
Michael
WN5T

[WA1HZK]

Thanks
I printed out the suggestions and I'll start with those.
Keith
WA1HZK

[KC4ALF]

Tnx for printing the mods. Picked up an SX-101 at Berryville last year and needs much work this will help.

[The Slab Bacon]

Remember that the mods that I posted were for a 101A and not a straight 101. I dont know that the component numbers are the same on the 101. They made many variations of this radio. Compare the skizmatic of the 101a to your plain 101 before making the component changes. They made 101, 101 mark1, 2, 3, and 101A, mark 1, 2, and 3 so you be sure which one you have and compare its skiz to the skiz for the plain 101a. Either way the circuits are similar and the mods will do the same thing, but the component numbers may be different.

                                                                    The Slab Bacon

[Pete, WA2CWA]

Remember that the mods that I posted were for a 101A and not a straight 101. I dont know that the component numbers are the same on the 101. They made many variations of this radio. Compare the skizmatic of the 101a to your plain 101 before making the component changes. They made 101, 101 mark1, 2, 3, and 101A, mark 1, 2, and 3 so you be sure which one you have and compare its skiz to the skiz for the plain 101a. Either way the circuits are similar and the mods will do the same thing, but the component numbers may be different.

                                                                    The Slab Bacon

I'm not sure where you're getting your info from, but there was an SX-101, Mark 1, 2, 3, and 3A. On the SX101A, there is no record of any Mark series for this model.
You can see some of the differences on the Hallicrafters (HCI) web site, under SX-101 lineage:
http://www.w9wze.org/

The Hallicrafters collector, Chuck Dachis, also makes no mention of an 101A Mark series.

[The Slab Bacon]

Pete,
        I know that they made many versions of the 101, exactly how many I dont know. (or care) But the component mumbers mentioned in my mods were based on the factory schematic for the 101A that I have. If he has a 101 or one of the other variants the component numbers may be different. I dont want him to get into trouble changing the wrong parts. He will have to look at the skizmatics for both and compare them to see what I did.
                                                                 The Slab Bacon

[Pete, WA2CWA]

Pete,
        I know that they made many versions of the 101, exactly how many I dont know. (or care) But the component mumbers mentioned in my mods were based on the factory schematic for the 101A that I have. If he has a 101 or one of the other variants the component numbers may be different. I dont want him to get into trouble changing the wrong parts. He will have to look at the skizmatics for both and compare them to see what I did.
                                                                 The Slab Bacon

No problem Frank. You made the same statement about the various models in your “The Slab Bacon’s ‘Receiver Road Test’” write-up under “General Technical Info” over on Steve’s site. My point was that people sometimes use what is written as “reference” and didn’t want them to be misguided with your incorrect identification of the models. Let me also point out that Hallicrafters, like many manufacturers of their day, often did impulsive assembly line component tweaks and often, they never made it into an updated schematic. Sometimes, the identification of a change, was only documented with a Service Bulletin” to the dealers.

For the record: 5 documented models for the SX-101, 1 documented model for the SX-101A.