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| Reviews Summary for Hallicrafters SX-100 (and S-85) |
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Reviews: 8
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Average rating: 4.5/5
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MSRP: $$325
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Description: General Coverage Communications Receiver
Double Conversion Superheterodyne. 14 Tubes
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More info: http://www.dxing.com/rx/sx99.htm
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You can
write your own review of the Hallicrafters SX-100 (and S-85).
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WA7VTD
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Rating: 4/5
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Apr 30, 2007 13:15
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My First Rcvr & Still Enjoying It
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Time owned: more than 12 months
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The SX-100 Mk II was my first receiver, and I used it exclusively from Novice licensure at age 15, past Advanced licensure at age 16 and today still turn it on for fun as a vintage station component as an Extra.
This review is a bit lengthy, but I hope it will help any new owner of this fine receiver to avoid common errors and to achieve full enjoyment of this classic radio.
I can't give it a "5" in view of the Collins, Hammurlund and Drake gear that existed at about the same time (although they were significantly more expensive than this rig), and I wish there were a "4.5" option, but I'll have to settle for a "4" -- which should not be taken as a slight in any way toward this very fine early Cold-War-era receiver.
This is a very easy receiver to align; just follow the excellent directions in the manual. You will need a VTVM to "do it right," but you can get away with a VOM attached to the speaker leads in a pinch. Remove the bottom cover, and just follow the sequence. A signal generator is needed to "do it right," but again, you can get away with a cruder method, by homing in on sigs of known frequency such as WWV, a local AM broadcast station, and your transmitter of known accuracy with the drive down, into a dummy load. (Or, an antenna analyzer such as the MFJ works great, also; it can be coupled to the antenna terminals of the SX-100 by winding a couple of turns of wire around the analyzer output connector, then just set the analyzer to the frequency called for in the SX-100 manual for each stage being aligned).
My first ham station as a new Novice in 1973 was the SX-100 Mk II with a rock-bound Knight T-60 XMTR. In the old crystal-control-only Novice days, the very poor frequency resolution on the SX-100 (demarcations on the ham bands every 20 kHz!) didn't matter, since one would call CQ in CW on one's fixed xtal frequency and then tune up and down the band listening for a reply in CW from another Novice rockbound on a different xtal freq. In many ways, it was much more fun than the high-pressure operating styles of today.
Upon earning the Advanced, a local old-timer, Ernie W7BPQ who was an Elmer of mine, gave me his Heath DX-100, which ended up dedicated to Army MARS CW nets after I managed to save enough money working nights for $1.85 per hour (and with some help from dear old Dad) to purchase a used HT-37, driving 200 miles to pick it up (which wasn't that bad, considering that my same-age best buddy and I had to find rides 110 miles one-way just to sit at the semi-annual FCC ham license testing sessions!). Then the real fun began! I had a really poor antenna installation for my QTH -- a Hy-Gain 18AVQ vertical ground-mounted on very resistive earth with only two radials per band and a mountain on one side. But it played OK to the South (worked Antarctica one late, groggy night) and to New England and occasionally Europe, and it actually was a boon to the very near West (Oregon, Washington) where its angle was high enough to get over the saddle of the mountain, not quite NVIS. My buddy had more open space around him a quarter mile away, and his SX-146 also seemed more sensitive; with his random-wire up 50 feet, strung between two lodgepole pines at each end of his parent's home, which we cut in the forest one day with the help of Dave WA7ROJ (another Elmer, ex-EL5B also, now SK), my pal WA7VTG usually beat the pants off of me into Europe with his straight key, often achieving 2 X 599 when I could barely hear them.
When it has good tubes and is recently aligned, the SX-100 is a very hot receiver, though, and an excellent example of quality double superhet design with one exception (noted later). The xtal bandwidth filters have nice skirts and provide 500 Hz, 1 kHz, 2 kHz, 3.0 kHz and 5 kHz selectable bandwidths (stock, unlike today's paradigm of "optional" filters, or optional "roofing filters" in the IF DSP rigs).
The notch filter works amazingly well. The audio fidelity on both AM and SSB is great, and there is a "treble cut" position that was intended probably for when the rig was used as a monoraul phonograph amplifier (there is an RCA jack phonograph line input provided on the rear chassis and a switch position for that function on the front panel), but that position worked well on strong SW boradcast stations also, and really filled a room with resonant sound when a nice large speaker was connected.
The only tubes I had to change over a period of 34 years were the RF amplifier (changed it 4 times) and the power supply rectifier (changed it three times); this was simply a function of heavy daily use of this receiver as half of an active ham station, with zillions of relay changeovers and exposure to strong adjacent transmitter signals every night and the radio left on almost 24/7. As far other tubes, it doesn't care much whether a 12AX7 is replaced with a 12AT7 or 12AU7.
Stability was indeed sometimes an issue, more so on some bands than others, especially (on mine) in the 15-25 MHz range. As has been noted, a good bump of the operating table would send the rig off frequency in those ranges, which was sometimes a problem on CW but not so much on phone.
I guess the complainers about the rig's lack of "full break-in" must use that term as it has been used since the 60's or so; i.e., QSK in which one can, for example, hear received signals at full sensitivity in between one's sent CW dits. With that working definition, of course this 1959-era radio didn't provide "full QSK," but it does have remarkably good, fast break-in ("semi-break-in") when paired with a transmitter such as an HT-32 or HT-37. One could either use an external antenna changeover relay, which provided an impressive three-clack sound when changeover between Tx & Rx occurred, or if one used separate TX and RX antenna, one could achieve quite rapid semi-break-in and the SX-100 remote stand-by cutoff was so good that the rcvr's sensitivity would not be diminished at all on each changeover.
IMPORTANT NOTE: When the SX-100 does demonstrate receiver desensitization for several seconds after changeover from TX to RX, this is a sign that the relay control tube in the transmitter is getting weak. Untold numbers of us relatively green hams either spent hours (and hours) carefully bending the various relay contact arms on the HT-37 to adjust the switching sequential timing in order to fix this problem, or spent an entire day enlarging the chassis relay mounting opening and replacing the original HT-37 relay with a modern relay...only to later realize that all we had to do was replace the transmitter relay control tube!
Changing bands was always impressive to friends, as this entailed 17 separate operations on the HT-37 & SX-100 in a precise sequence, which could be done in about 20 seconds after one got used to it; this produced lots of neat whistles and tuning sounds as one's hands flew all over the front panels of both rigs, throwing switches and turning knobs.
The schematic is very detailed and the radio is really not very difficult to trouble shoot. As was typical for its amateur gear, Hallicrafters incorporated into the manual the complete description of the construction and theory of each circuit in each stage of the receiver, and provided a full parts list, a lengthy alignment procedure section, and excellent troubleshooting algorithm, as well as tales of the various votages and resistances one should obtain at various test points.
The only true repairs I ever had to do (other than rotuine maintenance such as occasionally replacing the GE-47 lamps) were: (1) replacing the AC line cord in about 1979; (2) in 1989 (some 30 years after manufacture) troubleshooting and fixing lost reception in the second bandswitch position which included 80 and 40 meters. Studying the schematic led me straight to the culprit, a cracked ceramic capacitor. A couple of dollars later for a suitable, though not exact replacement, and I had it working as good as new after a few minutes of alignment. This is of note because I am not exactly an ace technician and I have stubby fingers.
The bandswitch should be worked frequently, as it will othwerwise become sticky and even damaged, as is common with older gear that is not used often.
I agree that this receiver is, in today's ham world, best suited for specialty AM work, where the lack of frequency resolution and occasional proneness to "bump instability" aren't of concern, or for SWLing.
In order to use the receiver on the ham bands, one first sets the main (left) tuning dial on a large white "index dot" near the megahertz frequency of the chosen ham band, with the gang for the right-hand dial (bandspread) fully closed. The calibrator is then switched on in order to find the precise alignment of the left vertical red line of the frequency dial window, on the index dot, with the bandspread dial set to the highest end of the ham band in question, zero-beated with the bandspread dial lined up at the highest edge of the chosen band (which will be multiple of 25 and 100 kHz).
The ham band setting process is made rather quick by use of the excellent logging scale system. Both frequency tuning knobs are indexed on their outer skirts in 100 numbered divisions, and each dial wheel has a logging number index. So, with a little chart at the operating desk, one can glance at it and see that for example, to put the receiver on 20 meters, one adjusts the main tuning dial to "1218" (I just pulled that out of my hat; it's not the real setting) which translates to the main dial being just advanced past "12" on the logging scale, and the outer skirt of the main tuning knob lined up on its pointer mark at "18." It then takes about one second to fine tune the setting and to peak the receiver for that band, both accomplished with the very stable xtal calibrator.
The antenna trim capacitor is next adjusted for maximum speaker noise/S-meter deflection and then the calibrator is turned off and you're ready to roll.
The bandspread (right-hand) knob and dial are then used to tune across the ham band in question, with the main tuning knob/dial remaining stationary (this is why a good bump can throw the thing off frequency). But unlike the SX-99 and earlier versions of the SX-100, the Mark II does not seem to suffer from frequency drift occasioned by such simple things as blowing into the cabinet.
Notwithstanding this Rube Goldberg-esque band changing procedure resulting in part from the bass-ackwards design in which the "wrong one" of the two receiver stages is fixed and the other is "wrongly" variable, I managed at age 16 to obtain the highest phone score in the old ARRL "CD Party" in the Northwest Division one weekend. It's too tedious for most operating now, but for work on only a few net frequencies, AM roundtables, vintage rig nights, straight key night, etc, it's no sweat and is kinda fun, and it is also an EMP-resistant rig which also can withstand substantial surges and variances in household line current.
For basic SWL or MW AM BC band listening, one uses the left main tuning knob/dial, and then fine tunes with the right bandspread knob/dial. Again, by using the logging indexing system of each one of those, it's very easy (after 30 minutes of warm-up) on a later date to return precisely to where a prior station was heard by, for example, setting the left dial/knob at, say "1786" and the right one at "1397" or whatever, corresponding to the settings at which the station was best received on the earlier date.
The "pitch control" doubles as a shape filter; pull it out one detent and it tightens the skirts on the CW selectivity filter. On SSB, the pitch control provides about 3 kHz of "RIT"-like adjustment in either direction, and on CW one can, with the pitch control and choice of sideband on the function switch, produce any kind of note which pleases the ear, from low, resonant, thumping beat to a high, sharp, blasting tone.
There is a very good internal electrical S-meter adjustment which with the aid of signal generator, permits the S-meter to be precisely and very easily aligned to factory specs (inject so many microvolts, adjust S-meter to reflect correct measurement). The large S-meter is very cool, and the "h" logo on it turns on a hidden pivot to reveal the mechanical zero adjustment for the S-meter.
The front panel antenna trim control knob is mounted on a long shaft attached to a variable cap at the rear of the inside, and over time the mating sleeve between the control shaft and the cap shaft will cease to provide a tight enough grip, causing slippage. Replacing the control shaft with somethng suitable (such as a cut-to-length piece of electric fence fiberglass stake rod) will cure this problem.
The dual frequency tuning controls have a very solid feel; they are mounted directly to heavy flywheels and the dial stringing method is very good, being combined with a direct-gear-driven mechanism such that there is zero dial backlash. If the dial string breaks, the manual provides excellent directions on restringing the thing and it's so easy that even I can do it, and probably even a caveman could do it.
The SX-100 -- at least the Mk II I've had since I was a teenager -- is really quite a remarkable receiver for its era and its cost at the time ($395 new in the late 50s/early 60's). Yes, that was a LOT of money in those days, but considering the many features such as the effective notch filter (better than the notch filter on my IC-735 and comparable in effectiveness to my IC-756 Pro II's manual notch), etc., it was worth its price at the time and has maintained its value today. It actually is kind of a steal at its typical prices today on the used gear market.
It also looks cool, especially in the dark. This will be an heirloom for my 11-year-old son. If bad times strike and I have to walk around clad in only a barrel, I'll make sure to swipe a shopping cart so I can hold onto my SX-100.
A bit of advice: please change the 2-wire AC line cord to a modern 3-conductor grounded line cord, for safety.
73 & enjoy your SX-100!
- Kevin WA7VTD
Oregon City, Oregon
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A few errors appear in my review above; I have corrected them -- and also provided additional information more user-oriented re. operating the rig and describing the band coverage, frequency resolution, aesthetics, construction, etc. -- in a separate review under a new dedicated review heading dedicated to the Mark II version of the SX-100 -- which also contains info unique to that final, best version of this receiver. If you are considering purchase of an SX-100, you may wish to go to that article in the SX-100 Mk II section, rather than expending time reading the somewhat lengthy review posted below. What can I say? I love this radio!)
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N6KYR
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Rating: 5/5
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Feb 4, 2007 10:42
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Great rig
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Time owned: more than 12 months
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Classic looking radio. You can have your I-ken-com job sitting next to it and any visitor in the shack will home on this beauty and "diss" the plastic. Take away the ricebox and replace it with a Ranger. Put a D-104 and a polished J-38 in the mix. Now that's some nice glow-in-the-dark action. Extreme eye candy for the operating table. It's 1957 all over again.
Back in the late '80s, I bought an earlier version from a college ham friend for $75. I had a ball with it. Only one problem was that the audio output transformer crapped out. I replaced it with a conventional 10k to 8 ohm replacement. Worked real fine except now I didn't have the alternative 4 ohm/600 ohm output selection.
I wouldn't trust it for regular SSB/CW ops unless I make a super conscious decision not to bang on the operating table. That's what I like to call "incidental contact instability." It's unsettling to be in a CW QSO only to have your station disappear in a disconcerting bang while you madly scramble to find your signal again. AM is a different story. Fat, solid and nice sounding.
Had it for about a year before I sold it (drat!)
But, I recently swapped for a Mark II (with SX-111 type knobs). It's the "famous" one that was written about in Electric Radio. That's my "keeper."
So if you find one, hang on to her for dear life. I know I will!
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SWL377
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Rating: 4/5
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Jan 29, 2007 21:59
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Great looking, good performing
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Time owned: more than 12 months
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If you marry for looks, get an SX 100. To my eye it is one of the best looking 50s era general coverage receivers made. It is just flat out gorgeous. Can it cook? Well... yes but not nearly as well as its plain (but not homely) sister, the Hammarlund HQ 180. I own both. The SX 100 consistently loses in side by side shootouts with the HQ 180. The HQ 180 is quieter, at least as sensitive, better SSB performance, and more stable on high frequencies. Still, I just love my SX 100. It performs well and looks GREAT. Til death do us part.
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VE3DJY
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Rating: 5/5
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Dec 26, 2006 01:43
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A Fixit Yourself CW Operators View of the SX-100
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Time owned: more than 12 months
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We all know that CW can penetrate the poor propagation conditions where PHONE often fails to make it. The SX-100 is perfect in many ways but lacks full breakin like most receivers of its time. I have owned my Hallicrafters SX-100 since 1978 and it has always served perfectly for me, but for one instance where the 2nd mixer screen resistor went open which is accessible only after considerable effort and care to remove the module - too bad Hallicrafters did not make this a plug-in module. It hears everything my modern equipment hears and the audio is comparable. However it is aimed at Amateur Radio so the fidelity is restricted somewhat - if I want better fidelity, I use my SX-62A. The frequency indication is of course analogue but is spring loaded gear driven and bandspread in the usual Hallicrafters philosophy so resetability is quite acceptable and backlash minimal for tuning in faint Morse signals. Finding the edge of the band is facilitated using the 100 Kc Crystal calibrator. Its sensitivity is comparable to my modern receivers but is more pleasant to operate. The STBY switch kills reception, a good thing for PHONE ops but not for CW as most TXs of this era had no sidetone. It could have benefitted from having full breakin featured. The SX-100 is remarkably sturdy compared to lesser offerings like my SX-99 and weighs accordingly a bit more. It is not so compactly layed out that one cannot get in to do any service or repair work. However, if you have to remove the module, pull in hookup wire leads so that the module's leads can be pulled back in along their original path. The "lid filter" works nicely and notches out annoying heterodynes very well. The feel of the controls is typically Hallicrafters, quality and elegance combined with practicality makes for success, and are easy to use. I am loath to modify any classic gear and I will refrain from adding QSK and keep it 100% original. In pursuit of repairing the second mixer above, it was discovered that the screen grid resistor, as well as being open, had never been soldered to the lug. Unfortunately Hallicrafters is like many radio makers now only a fond memory of the peak of American achievement in radio ranking. Their new owners seemed to not understand what it was that made them great, it is a fragile lifeline not well understood by all.
I have never used a better receiver, even though I have an HRO-60 and an AR88-LF which occupy prominent places in my shack. It does all the others do but uses less space without being cramped.
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KC0LUL
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Rating: 5/5
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Oct 24, 2006 11:49
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SX-100 or SX-71
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Time owned: more than 12 months
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I did have an SX-100 but it was destroyed by a house fire,my SX-71 survived and it I believe is just as good of a radio as the SX-100.
(Both radios are first rate!)
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KA8DLL
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Rating: 5/5
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Oct 24, 2006 11:21
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best general coverage radio make by hallicrafters
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Time owned: more than 12 months
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Best general coverage radio made by Hallicrafters. Second best is an SX122. Variable selectivity and notch filter do a good job on bring in ssb. Very attractive front panel. Geared tuning feels like a precision instrument while tuning. Comes close to a general coverage SX101.
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PY2EWP
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Rating: 4/5
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Apr 19, 2006 15:02
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Small correction to previous review
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Time owned: 6 to 12 months
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Just one small correction to W2SX evaluation of the Hallicrafters SX-100 : this model does have a kind of product detector and does have AVC while receiving SSB
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W2XS
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Rating: 4/5
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Jun 9, 2004 23:00
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Fun Vintage Radios
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Time owned: 6 to 12 months
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I decided to combine both of these receivers into one review even though they are somewhat different.
The SX-100 was a high-end radio in its day and the S-85 was more low-end, but they both work very well for AM broadcast and short wave listening today. I own and use both of these radios (along with a bunch of other
vintage radios).
These receivers came out in the mid 50's when SSB was in its infancy. They both share a tunable first oscillator system and a fixed second oscillator- unlike the Drakes and Collins that use a tunable second oscillator and a
fixed first oscillator - a big difference in stability and dial calibration. The Drake/Collins approach resulted in a design where all of the bands have the same dial readout. If good CW and SSB reception is wanted for use with a transmitter, then any Drake or the later Collins receivers will win hands down. Neither of these two Hallicrafters has a product detector nor do they have AVC in the CW/SSB modes. The SX-100 would be my choice for a vintage AM station, and the S-85 is a good choice for general SWL use. I like having the general coverage of these types of receivers as opposed to a ham-bands only receiver.
Keep in mind that these tube type receivers will need some maintenance at some time - tube replacements, new electrolytics, etc. Keep an eye out at hamfests and you will be in good shape.
The internet (eBay, e.g.) has loads of tubes too, some NOS. I can keep my Hallicrafters going
for several generations thanks to people selling tubes at reasonable prices (unless BPL wipes us out, that is).
Here is a list of differences and similarities:
Both:
General coverage, with calibrated ham-band band-spread tuning.
6SC7 and 6K6 audio amplifier stages - plenty of audio, good sound.
Separate BFO circuit and diode detector (no product detector).
CW/SSB listening with AVC off, AF gain turned up, and RF Gain turned down.
Pretty good sensitivity (even on band 4).
Pretty good dial calibration.
Automatic Noise Limiter (old fashioned).
Automatic Volume Control (useable only on AM).
Variable BFO pitch control for CW.
Tone control.
Large half-round dials.
SX-100:
Double-conversion (1650kHz/50kHz).
L/C filters at 50kHz (like the Drake 2B and R4, R4A, and R4B).
500Hz to 5kHz selectivity - a tiny bit narrow for hi-fi SWL use.
Single-signal selectivity on CW. Good rejection of opposite sideband.
The 50kHz IF section is on a sub-chassis. Very difficult to get to.
Really nice lit-up dial using 4 bulbs.
One RF and three IF stages - a lot of gain!
Antenna trimmer control (for peaking the signal).
Nice S-meter calibrated in S units and microvolts.
Notch filter.
Needs an external speaker.
Very smooth gear-driven dials. Very good re-settability. (Tuning knobs also have scales).
Voltage regulation for better stability.
"Miniature" tubes like the 6BE6 etc.
Criss-crossed front panel that is easily scratched.
Built-in 100kHz calibrator that puts out a strong reference signal.
The SX-96 is similar but without the notch filter (and 1 less IF stage).
The SX-88 is also similar but who has $10K to spend on one.
The S-76 and SX-122 have the same IF frequencies.
S-85:
Single conversion (455kHz) - some images at higher frequencies.
No selectivity other than the IF transformers and a tone control.
No S-meter (but one can be added externally).
2 bulbs light the dials. Not as brightly lit as the SX-100.
One RF and two IF stages - pulls in a lot of stations (more than my S-38).
Built-in top-facing speaker (works OK - and convenient).
Requires high-impedance headphones (which I don't have).
Slight backlash on the main tuning control (not gear driven).
No voltage regulation (OK for AM listening but CW can sound warbly).
No calibrator.
Uses larger tubes such as the 6SK7.
The SX-99 is similar but has a one-crystal filter, S-meter, and no speaker.
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