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Subject line says it all. Thanks & 73, Jeff W8KZW

A note about the color code on resistors in the SX-23 and perhaps other receivers of this vintage. The colors stand for the same numbers as in current practice but the bands are read differently. The first number is the "body color" which is the color of the two wide bands of the same color separated by a narrow band. On one end of the resistor is the silver or gold color indicating tolerance, just like today. The band between the tolerance color and the body color is the second number. This used to be called the "tip color" before tolerance bands were used. Then the narrow band that separates the two wide body color bands is the number of zeroes. The best illustration of this that I have found is https://www.radioremembered.org/rescode.htm#:~:text=Basis%20of%20the%20RMA%20Resistor,or%20as%20a%20body%20color Figure 2 is the one to use but it should have also shown the silver or gold tolerance band at the left end. Bob Krassa AC?JL

I am about to start restoration of an SX-23. It works but not perfectly. It was apparently recapped early in the plastic capacitor era but needs some cosmetic and mechanical help. I am asking for help with the following questions. Cabinet paint. Was the original cabinet paint smooth or wrinkle? I have seen pictures of both black and light gray cabinets where it looks like a very light wrinkle but could even simply have been paint with sand grains mixed in? Front Panel. My front panel needs help, probably best an overlay. Does anyone know of someone who can make one and does anyone have a good image of an SX-23 front panel that I can provide to such a company if they don't already have? I think the word I am looking for regarding the image is orthogonal, that is the same scale in all directions. Maybe dry transfer lettering or decals would also be feasible - can anyone recommend sources? S- meter mounting. My s-meter works which is very fortunate but it is not well attached to the front panel. Can anyone provide a description or a picture of the back of the front panel in the s-meter area that could show how it is attached to the front panel? There are no screws into the meter housing through the front panel. Maybe it was just held in by the tight springy sheet metal wrapper? Bandspread dial indicator. The bandspread dial indicator mechanism is missing. The bandspread works and there is still some dial cord from the bandspread switch shaft that I can see was routed to the indicator mechanism. I found a blurry picture which shows the pulley for the bandspread indicator is about 2 inches diameter. Can any one provide the exact diameter? It looks like the pulley is on the back end of a short shaft and toward the front there would probably be a clear circular piece of plastic with a radial black line. There would also be a bracket for the dial light. I might be able to build such a mechanism but it would help to have a description and pictures. Of course if someone would be willing to sell one of these mechanisms I would be interested in purchasing! On the under side, there is a shelf along each side of the chassis on which there were some components. Can anyone tell me or confirm what those components were originally? Looking at mine and at some pictures of the underside that I have seen, it looks like Power Transformer Side. On the power transformer side the shelf had a candohm resistor. These were used in many radios of that vintage and are a long flat metal can containing a wire wound tapped resistor. For example, on the SX-28 R31 and R32 are the two sections of a candohm resistor, used as a voltage divider for screen voltage. On the SX-23 the candohm serves the same purpose and comprises R30 and R31. On mine the candohm was replaced by two separate resistors. My only question on this side is whether there was anything else on this shelf originally? I.F. Transformer Side. It looks like the only items on the shelf were R20 and C68 connected to the headphone jack, toward the front of the radio. There is an unused hole in that shelf toward the rear. Again here my only question is whether there was anything else on this shelf originally? Any information will be much appreciated! Bob Krassa AC?JL

When I first got my HT-44 running, I was using a high impedance Heathkit microphone and had no trouble achieving full output from the HT-44 with a relatively low mic gain setting (around 3). When I switched over to the main station microphone, an Inrad M629 dynamic (600 ohm impedance), the best I could do was around 50 watts output with a mic gain setting around 8 on the HT-44. I also have a Drake T-4XC which has a high impedance input and had the same result with the Drake. I looked around for a reasonably priced solution and found this: It's a model CP8201 inline impedance transformer sold under the ATUS label and manufactured by Audio-Technica. The primary impedance is 250 ohms and the secondary is 50,000 ohm. Input is a three pin female XLR connector and the output is a 1/4 inch plug. The price of the device is around $15. My Inrad mic uses an XLR cable and I installed the device inline at the end of the mic cable and made another short cable to connect to the HT-44. The matching device solved the problem with using the dynamic mic with the HT-44 and I am able to achieve full output with the mic gain set around 3 on the HT-44, same as with a high impedance mic. There are many other types of matching transformers available on eBay, most being a bit more expensive than this one. Another good source of matching devices is Reverb.com, but prices are a bit higher there. 73, Floyd - K8AC

Hello all. Somehow, this group disappeared from my groups.io list, so I re-applied. Back in the 1970's I ran an HT-37 with good results--a fine transmitter. I sold it to a friend, and after about 6 months, the power transformer died. (Not to merge into the other HT-37 transformer thread) Recently, I found another HT-37 that was said to be in good operating condition. It showed a few problems on testing, but I picked it up anyway. The plate tune capacitor was arcing--that has been resolved. A hum in the transmitted signal led to re-capping the rig. No more hum in the signal. I replaced the 5R4 and 5V4 rectifiers with plug-in diode/resistor modules to take the HV off of the transformer filament windings; inrush current limiters are installed ahead of the primary winding. Three tubes were weak, including a 6146. The 6AB4 (heterodyne oscillator) was very weak and one of the 12AT7's in the SSB generator had been replaced with a 12AU7A. All have been replaced with good or new tubes. In SSB mode, the carrier balance works and properly nulls the carrier. My questions: #1. All bands function except 40 meters--it is dead. Thoughts? #2. The audio section produces a strong signal relative to the amplitude of the voice audio input in the SSB modes, but the audio is not heard in a local receiver. Just a muffled hint that there may be audio there. I didn't have a 10uf 350VDC capacitor to replace the electrolytic in the audio section, so I temporarily installed a 33uf 450 in its place. It appears to be a DC filter ahead of the 12AX7 plates and not in the audio stream. Thoughts? The HV is running high at about 1000 volts. It's higher than the 750 VDC in the schematic, but I have a plan for that. Regards and 73. Russ KW6T "The cheap item is rarely the least expensive."

Did just recheck and yes, there is a capacitor at the input and then the swinging choke. When I built my rig we started with the semiconductor diode bridge and down the road I realized I did not need to have that choke in there. My High B+ jumped from around 700 to near 1000. I get away with this because I run 6146Bs and not 6146s. Whistle down gets down to under 900 under load which they can handle. Interesting note and maybe also important, the HT37 was rated for use of line voltages from 105 to 125. Not uncommon to find higher such as I have discovered here up to 130+! Thus running my vintage transformer type rigs off Variacs set to 115. My original manual also does have the CAUTION note about pausing when switching the rig off but does not go into details on why. Thought on the crystal (which was my first thought on this). First exercise the crystal for the problem band by unplugging and reseating a couple of times to see if it comes back to life. Easiest fix. If the crystal is sluggish in starting, you can try a separate different value resistor for that one to ground. Per Mr Orwin, the single resistor was the production value that would work most of the time for most crystals. If you don't mind a little testing, you can actually set a best value for each xtal. They had no time for this on an assembly line so used one resistor for all. Good luck. Ed, WA9GQK On Wednesday, August 14, 2024 at 06:36:42 PM CDT, edward schumacher <eddiewa9gqk@...> wrote: The HT-37 as built did not have a capacitive input filter. There is a swinging choke at the input which was commonly used with tube rectifiers. Ed, WA9GQK On Wednesday, August 14, 2024 at 02:42:47 PM CDT, don Root <drootofallevil@...> wrote: Halden, Russ too Re “just a tad above 1000 V in STBY mode.” I think I made a question comment on Hilden’s topic, saying that I could find no information at all for the conditions under which the voltages in the chart or elsewhere were taken; so I am guessing / we are guessing? , and as I recall there is no AC voltage anywhere for transformer HHv or the 5R4 plate voltages. Without knowing enough about the operation, if one guesses or knows that STBY draws very little current from B++ , the power supply may well have been designed to unload into the higher voltage region typical of capacitor input filters. and I should not say it here , but dumping a small current from the 8 Henry is not at all the same as dumping the energy of its rated 150 mA somewhere when turning the rig off with no pause in STBY.

SR-150 information. I have had several contacts lately about problems with the VFO in the SR-150. I put together a document specifically addressing issues with the VFO, how to test subsystems and alignment. I have published it on my website. It can be downloaded @ wd0gof.com/hallicrafters-radio/technical-discussions/sr-150/ Walt Cates, WD0GOF https://wd0gof.com/Hallicrafters A majority of acceptance is not proof of correctness. https://wd0gof.com/bible-study/commentaries/

A rainy day here and thought I'd dig into the SX-117 again and investigate the AVC pumping situation that's been discussed in the past. For those not familiar with the problem, the symptom is that AVC "pumping" and associated desensitization occurs with strong nearby signals outside the receiver passband. I have a late model 117 corresponding to the "D" level schematic. I've moved the tap for the AVC amplifier to much later in the IF chain, to pin 3 of T8. That's the source of the IF signal for the product detector and my thinking was that the AVC amp shouldn't be seeing any signal that I'm not hearing. Turns out that isn't true. Testing was done using the calibrator signal. In SSB mode with the selectivity in the 5 kHz position, I don't see the problem. Same is true in the .5 kHz position. But in the 2.5 KHz position it is there in spades. When I tune across the calibrator signal, I see the expected rise and fall of the S-meter and when I'm tuned about 3 kHz above the carrier frequency, the S-meter reads about nothing as it should. But, as I continue to tune below the calibrator frequency (in LSB mode), as I approach 4 kHz above the calibrator signal, the S-meter rises again and reaches a peak very slightly greater than the peak seen when tuned to the signal. When this occurs, nothing is heard from the speaker or phones of course, but the S9+ signal desensitizes the receiver. It appears that the unwanted signal is reaching T8 via some other path than the desired signal. Any ideas on what could be happening? With the AVC source tap where I have it, the notch control works with the AVC and if I turn the notch control all the way counterclockwise, the S-meter reading of the phantom signal is reduced slightly. Does your 117 exhibit this same behavior? 73, Floyd - K8AC

I just received a DVD I bought on FleaBay that contains volumes 1-23 of the Riders Manuals. I scanned through a little of it and found pages of radios I've never even heard of! 73, -- Justin B. KI5GKD

A few months ago I acquired a Hallicrafters SX17 receiver intending to restore it as a winter project. Well the winter months have come and gone and I have finally gotten around to getting it on the bench (without injury to self I might add - it is a bit of a boat-anchor!) for a preliminary look. This is my first time on here, so just wanted to say hello to everyone and thank the moderator for accepting me into the group. As might be expected for something from circa 1937, the radio is in a bit dirty and metal surfaces are oxidized. Some of the wiring (particularly the mains) looks a bit of a mess and will require re-wiring, but the immediate showstopper is the fact that the power transformer (T7) has an open primary. There seems to be no indication on the radio of the mains input voltage, however, I have read that these were made to be powered from a 110Vac line? Since the radio is located in the UK, it may have been previously assumed that it would run from UK mains which is at 230Vac, which might perhaps explain the open transformer.... Can anyone confirm whether these were ever made for the UK market and for 240Vac mains supply? The next question is whether it is possible to source a replacement? The manual I have found does not indicate the transformer voltages so I wondered whether anyone has this information? This looks like it is going to be a huge project but I think it would be interesting to restore this circa 90 year old receiver if possible.

I am looking for an HA-16 vox adaptor. It doesn't have to be functional, as long as it is complete and not "over-modified"?. Walt Cates, WD0GOF https://wd0gof.com/Hallicrafters A majority of acceptance is not proof of correctness. https://wd0gof.com/bible-study/commentaries/

I figured it was time to take a break from Heathkit Transmitters, and such, so my brain could rest for a while. I thought what better way to rest up than going through a Hallicrafters receiver that was different than the ones I have. I picked this 8R-40 for a pretty decent price and it looks great and even has all of it's knobs, which is a rarity for me. It should be here by weeks end and I'll get the caps ready! :-) Here one of the FleaBay pics... 73 -- Justin B. KI5GKD

I obtained a Hallicrafters S-38B which is missing both the knobs and their external knob shafts for the tuning and bandspread functions. The metal shafts and brackets inside the radio are in place and the dial cords are still fitted. My question is: What material are these shaft extensions made of which connect the knobs to the internal tuning shafts? Are the shafts plastic or metal? I suspect they are most likely made of plastic, but want to confirm this before proceeding with the restoration. Cheers Ron VK2IRS

This pdf copy was scanned via OCR so it is searchable so it is much easier to find tidbits. https://www.worldradiohistory.com/BOOKSHELF-ARH/Technology/RCA-Books/RCA-Radiotron-Designer%27s-Handbook-4th-Edition-1953.pdf I agree with Richard, it is a must have book that will answer most tube radio questions. Jim Logic: Method used to arrive at the wrong conclusion, with confidence. Murphy On Saturday, August 3, 2024 at 08:43:04 PM CDT, Richard Knoppow <1oldlens1@...> wrote: I meant to say that the Radiotron 4th edition is available as a PDF from several sources on the web, all free. For instance tubebooks.org Despite its age this continues to be a very useful and interesting book. IMO a must have. On 8/3/2024 10:11 AM, John via groups.io wrote: I pulled down the user manual for the SX18 and had a look at the -- Richard Knoppow Los Angeles WB6KBL SKCC 19998

Another reason that early – and still, many, many – elevators run on DC is that a shunt would motor produces huge torque while starting. Add to that, a number of relays (contactors) with differing amounts of resistance (at high wattage) as the controller interface, and you get strong, smooth acceleration and deceleration, low vibration, and easily adjustable t positioning for no-trip-and fall-down entry and exit to and from floors. A building I worked in years ago had an early (around the mid-‘50s’) variety AC elevator. It was jerky upon starting and stopping, and would jerk-jerk-jerk when leveling at each floor for ingress and egress. Conversely, a building in which I installed an FM translator years ago had DC elevators. In the elevator room there was an incessant clicking reminiscent of being in and old telephone step-by-step (Strowger) central office switch room. Those DC elevators were smooth as silk. I suspect, but don’t know, that current elevators likely still use rectified AC to provide DC for the motors, perhaps now controlled on the AC side by triacs rather than the power-wasting resistance ballasts. It would be interesting to know! Mike/ K5MGR ___________________________________ Mike Langner 929 Alameda Road NW Albuquerque, NM 87114-1901 (505) 898-3212 home/home office (505) 238-8810 cell mlangner@...

Fair to say that after some 20 years of use, this group is using perhaps 1GB of the 30GB allotted? Perhaps some dos and don'ts on group posting etiquette from the boss? I ask this since some posters eliminate the original thread which makes it difficult, at least for me, to remember what has been said in previous posts within the same thread. Jim

First time shipping this power supply so I thought I'd solicit suggestions. For example, I know to separate a Collins 516F-2 from its cabinet before shipping - any similar caveats here? I am not asking for generic help with packaging - I've shipped delicate radio equipment across the globe successfully. Rather, I seek specific product-related advise, if any. Thanks, & 73, Jeff W8KZW Jeff Bauman 11390 Clark Rd, Davisburg, MI 48350 Boatanchors since 1965 (WN2SCH, WB2WRH, WB5KZW)

Bought from a local estate a few years ago. Finally got around to playing with it. Replaced caps and tested the tube, seemed to be in good shape. After a warm up period the audio is solid at 400 hz. Now on to the RF portion. Any idea for a source of these Pin Tip leads? Any other advice for this particular model? trentfleming.com

Has anyone designed a sidetone oscillator for this pair? 73, K8AC

Finally got back to looking at this problem. In short, the problem is that when sending CW in what Hallicrafters called "break-in" mode (Operation switch in VOX position), the first dit or dah sent is severely truncated to the point that a dit might not even be heard at the other end. Looking at the timings observed by Halden, if we could just somehow lengthen the leading dit or dah by 30 ms. or so, we would mask the problem and all would be well. I read through a lot of posts on the K1EL group here on groups.io (Winkeyer info) and found that K1EL had already thought of that solution and built it into the Winkeyer USB. In the Winkeyer USB settings, there's a parameter called "1stExt". If you put a value in there in milliseconds, Winkeyer will automatically lengthen the first dit or dah sent by that amount of time and all other dits and dahs are unaffected. I used the Winkey utility called "WinKey2 Standalone Editor" to play with the value and at 30 ms. it sounds pretty good. Later I'll hook up the scope and make a final adjustment of the value. This solution makes the HT-44 a very decent CW rig where before it was useless to me. 73, Floyd - K8AC