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Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
开云体育Jim? thanks from us! so both are similar, peaking too low Poor low band may be due to No “C 62” as in the S40B ?? ? From: [email protected] [mailto:[email protected]] On Behalf Of JThorusen
Sent: Wednesday, February 19, 2025 9:51 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak! ? Greetings to the Group: ? ?? I attempted to replicate Emanuele's measurement of the RF tank circuit.?? This required that I construct an RTMA dummy antenna, which turned out to be a bit of a chore; I had to make the 20 uH coil as I didn't have anything close in stock.?? Since Emanuele used a spectrum analyzer with tracking generator, I decided to do the same.?? The tracking generator output was connected to the antenna terminals (with the low side jumper to ground in place) through the RTMA dummy antenna.?? The signal was taken from the RF amplifier (V1, 6SG7) control grid, pin 4 with a 10:1 oscilloscope probe.?? The receiver main tuning dial was set to 1.4 MHz.?? The tracking generator level was set to 0 dbm to obtain adequate signal for display.?? The sweep range was from .5 MHz to 1.6 MHz.?? 10 db/division vertical scale. ? Here are the results: ? This is the response with C4 set to minimum capacity. ? This is the response with C4 set to maximum capacity. ? ?? Incidentally, my receiver also displays considerable sensitivity change over the broadcast band.?? At the high end, there is considerable 60Hz hash and noise as one would expect in a suburban environment.?? As one tunes to the bottom of the band, the receiver becomes virtually quiet.?? I live a fair distance from the nearest AM broadcast station and I was unable to hear anything on the pair of clip leads I was using for an antenna; only the above mentioned noise. ? 73, -- Jim T. _._,_._,_ -- don??? va3drl |
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Re: SX-28A Hum
I am not sure that the problem is resolved.? CH2 was replaced with a similar value choke with less winding resistance so it will have higher Q.? Higher Q will affect the audio filter curve so there will most likely be more ripple in the audio bandpass in the bass out switch position.? This may not be that noticeable to the ear but the scope will see it. In Tom's first video, at about the 45 second mark, the scope shows a strange waveform.? The main peaks are of a 60 cycle waveform.? The center peak is at 120 cycle but it's peak is negative, the two remaining peaks are at 240 hertz and positive.? There must be some nonlinearity to cause these harmonics to be generated.? This nonlinearity is acting like a diode and causing the second and forth harmonics of the 60 cycle waveform. Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Wednesday, February 19, 2025 at 02:13:41 PM CST, Richard Knoppow via groups.io <1oldlens1@...> wrote:
Thank you. Since its a different choke it doesn't explain why the original was humming. Doesn't matter if the problem is solved but would be interesting to know. Its possible there is a leak between the winding and core or frame in the original. A sensitive ohm meter would probably tell. I had thought of suggesting putting the old choke on an insulator (just a sheet of paper) temporarily to see if the hum stopped. Not worth taking the new choke out to try. The SX-28 is an interesting receiver, an attempt by Hallicrafters at advanced engineering that didn't quite come off. The Lamb noise blanker was a very good idea but was not well implemented. Eventually, Drake and others, did a better job with it. This type of blanker works well on pulse type noise, like ignition noise, but hardly at all on the more common (now) power line noise. Hallicrafters eventually published a modification (on BAMA) to disable it and replace it with a conventional series limiter. I hope not many SX-28s were mutilated this way. On 2/19/2025 11:57 AM, thoyer via groups.io wrote:
Yes, I replaced the original CH2 with another 4hy one I had from an -- Richard Knoppow Los Angeles WB6KBL SKCC 19998 |
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Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
开云体育Hello Emanuele, ? Did you see any part number on the Main Tuning Capacitor ?(C7) ?? It should end with 341… ? As you seems to have a LCR meter, can you also measure C7A (the section of the main tuning capacitor that tunes the Antenna Coils ?? It can be easy with L3 being removed. Please measure the fully meshed and fully open values. ? And, being there, can you also measure the inductance of the two L3 windings, please ?? From those measures, we can try to make sense of what is happening. ? It will be also good if you can take pictures of the L3 coil, seen from the top, and also from the bottom. Can you see something in the center hole, or not ? ? 73, Jacques, VE2JFE in Montreal ? De?: [email protected] <[email protected]> De la part de Emanuele Girlando via groups.io ? Don, no idea about the run of this unit. The serial on paper is almost impossible to read; looking carefully it seems read "serial. 196479". No other info. Here is an info briefing: As arrived, the radio looked fully original. I recapped it following this rule: do not touch anything in RF sections (ANT, MIX, OSC) unless something proves to be really faulty. Main filter caps were retained as they measured good and perform well. Checked all resistors and replaced when out of value (above the required tolerance). At the end of the job all voltages where very close to the ones indicated in the service manual. One exception: V1pin6 measures 140V instead of 125Volts. V1 and V2 measured "good" and "very good" respectively on my simple emission tube tester. As I said multiple times the radio works, but:
Furthermore, it appears that no one here can fully understand how these strange RF ANT and MIX circuits really work, making fault finding process close to impossible - really frustrating. What surprises me a lot is that in more than 70? years no one has ever raised a hand on the subject: we all were not able to find any reference to the problem... IMHO, the best way to represent what's going on is the following picture: ? Today I torn down L3/C4 assembly. Here it is. ? In DC, using 4 wire measurement procedure, the first coil (pins C and D) measures 5ohm, while the second (pins A and B) measures 1.5ohms, all in line with what is reported in the S-40B service manual for the same L3 (even if the part numbers differ...). The TRIMCAP, measured with an LCR meter, ranges from 1.7pF to 30pF - good to me. ? ? ? Now I have to go. Tomorrow I am going to check the ANT and MIX wiring... and S1 wafers positioning... -- Emanuele (IU1KNR). |
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Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
开云体育Emanuele Real good pics! The knowledge that it looks original helps reduce speculation that it has been modified and that is causing the problem.. good to know about that. The trimmers for band 4 have a range of 20 to 1 while the others are 10 to 1. ? About L3 ?just thinking out loud, when in band 1 the incoming signal arrives at the top coil, where there is a tendency for it to peak at say ??4Mcs due to its trimmer ?but that should not hamper the signal on band 1. ?The tuning of the lower coil is mostly done by the main tuning cap in resonance with that lower coil[schematic view not physical], then the signal is passed thru the switch to the V1 grid. We expect some interaction? between c4 and c3 but ?L3 lower for band 1 ?is likely using the top coil just to transfer the signal, and maybe isolate this tuning from the antenna. when the dial is at the top it resonates at 1.6 ? mc while the upper coil remains near 4mc , still well away from 1.6. It is the same idea for band 2. But swap all the stuff. Here the lower coil has only its trimmer connected and wants to resonate ??at 1.6 or whatever which is not much lower than band 2 bottom? so I wonder about that Note I hate using all these “I’s” but it is how I am thinking for good or bad, its far from a law. The Mixer has similar coils and caps but the switching seems more normal BUT ?the big mystery of V1 v2 coupling The S-85 ?Mixer tank area seem to be identical to the S-40B, except for the C62 which maybe does enough coupling at resonance [] So I am convinced that the antenna tank might work in general but but why it wont peak high enough remains a big mystery. ? Maybe put L3 back but don’t connect the variable caps, and try a sweep to see how high the frequency goes, then perhaps connect the variable one at a time and contemplate that. Hope you get the gist of this stuff, but don’t quote me! From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io
Sent: Wednesday, February 19, 2025 5:59 PM To: [email protected] Subject: Re: [HallicraftersRadios] S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak! ? Don, no idea about the run of this unit. The serial on paper is almost impossible to read; looking carefully it seems read "serial. 196479". No other info. Here is an info briefing: As arrived, the radio looked fully original. I recapped it following this rule: do not touch anything in RF sections (ANT, MIX, OSC) unless something proves to be really faulty. Main filter caps were retained as they measured good and perform well. Checked all resistors and replaced when out of value (above the required tolerance). At the end of the job all voltages where very close to the ones indicated in the service manual. One exception: V1pin6 measures 140V instead of 125Volts. V1 and V2 measured "good" and "very good" respectively on my simple emission tube tester. As I said multiple times the radio works, but: 1.???? IF aligned seamlessly; 2.???? bands 1 & 2 trimcaps don't peak during alignment; 3.???? sensitivity close to zero in the lower part of band1; can hear stations on the higher part of the band; 4.???? bands 3&4 work much better and the trimcaps peak during alignment (even if we have seen the ANT and MIX peaks behave like the ones in band 1&2. May be the trimcaps range is much larger allowing the tanks to reach the alignment frequency. Still I have to check if sensitivity remains constant all over the bands.. 5.???? while keeping reasoning about the RF circuits I replaced R26 as you can see in my previous posts pictures; 6.???? once again I can assure C5 was fully OPEN while performing all test; 7.???? both the variable capacitors seems in good shape; nothing prevent them from traveling the entire route, in one direction or the other. Furthermore, it appears that no one here can fully understand how these strange RF ANT and MIX circuits really work, making fault finding process close to impossible - really frustrating. What surprises me a lot is that in more than 70? years no one has ever raised a hand on the subject: we all were not able to find any reference to the problem... IMHO, the best way to represent what's going on is the following picture: ? Today I torn down L3/C4 assembly. Here it is. ?
In DC, using 4 wire measurement procedure, the first coil (pins C and D) measures 5ohm, while the second (pins A and B) measures 1.5ohms, all in line with what is reported in the S-40B service manual for the same L3 (even if the part numbers differ...). The TRIMCAP, measured with an LCR meter, ranges from 1.7pF to 30pF - good to me. ? ? ? Now I have to go. Tomorrow I am going to check the ANT and MIX wiring... and S1 wafers positioning... -- Emanuele (IU1KNR). _._,_._,_ -- don??? va3drl |
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Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!
Don,
no idea about the run of this unit. The serial on paper is almost impossible to read; looking carefully it seems read "serial. 196479". No other info.
Here is an info briefing:
As arrived, the radio looked fully original.
I recapped it following this rule: do not touch anything in RF sections (ANT, MIX, OSC) unless something proves to be really faulty. Main filter caps were retained as they measured good and perform well. Checked all resistors and replaced when out of value (above the required tolerance).
At the end of the job all voltages where very close to the ones indicated in the service manual. One exception: V1pin6 measures 140V instead of 125Volts.
V1 and V2 measured "good" and "very good" respectively on my simple emission tube tester.
As I said multiple times the radio works, but:
Furthermore, it appears that no one here can fully understand how these strange RF ANT and MIX circuits really work, making fault finding process close to impossible - really frustrating. What surprises me a lot is that in more than 70? years no one has ever raised a hand on the subject: we all were not able to find any reference to the problem...
IMHO, the best way to represent what's going on is the following picture:
?
Today I torn down L3/C4 assembly. Here it is.
?
In DC, using 4 wire measurement procedure, the first coil (pins C and D) measures 5ohm, while the second (pins A and B) measures 1.5ohms, all in line with what is reported in the S-40B service manual for the same L3 (even if the part numbers differ...).
The TRIMCAP, measured with an LCR meter, ranges from 1.7pF to 30pF - good to me.
?
?
?
Now I have to go.
Tomorrow I am going to check the ANT and MIX wiring... and S1 wafers positioning...
--
Emanuele (IU1KNR). |
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Re: SR-500 Tornado
开云体育Hi Scott,
Talk about timing...
I have an SR-160 (upgraded to
SR-500), an SR-400, and matching P-500 power supply that I would
like to find a good home for (all in good working order and
condition).
The SR-160 is a bit of an oddball in
that the original VFO had been replaced with a solid state VFO
when I got the rig. I don't know if this was something done by a
previous owner, or as a factory experiment or prototype. Because
this rig was already non-standard, I made the changes to upgrade
it to be functionally equivalent to the SR-500. Walt Cates (who
replied to you earlier and whom I consider the expert on these
rigs) had put together a list of differences/changes between the
two rigs.
As I only have the one power supply
(which works for either rig), I don't want to break up the set.
By the way, I also have an SR-2000
and matching P-2000 power supply. All of these are great rigs,
even by today's standards (especially for someone who likes to
fiddle with real knobs instead of a computer screen).
Like you, I started in ham radio
early in life, getting my novice license in 1957 at the age of
12 (KN7DYB). Since then, I have been in and out of ham radio
depending upon the demands of real-life. When I retired from the
computer industry, I had enough time (and money) to nurture my
interests in vintage tube-type ham radios. I am more of a
restorer and tinkerer rather than operator, although I do get on
the air occasionally, mostly to check out whatever project I am
working on at the time.
If you are interested, I can send you
more information (photos, etc.). My email is good on QRZ.com.
Bob,? K7DYB
- - - - - - -
On 2/19/2025 1:21 AM, Scott WA9WFA via groups.io wrote:Hi, Lately I’ve been waxing nostalgic about the old Hallicrafters transceivers. ?A friend loaned me his SR-160 for several months back in 1971 while I was in Senior in High School and I used it for that summer before heading off to the Vietnam War. ? It was a wonderful transceiver! ?
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Re: SR-500 Tornado
开云体育Hi Scott,
Talk about timing...
I have an SR-160 (upgraded to SR-500),
an SR-400, and matching P-500 power supply that I would like to
find a good home for (all in good working order and condition).
The SR-160 is a bit of an oddball in
that the original VFO had been replaced with a solid state VFO
when I got the rig. I don't know if this was something done by a
previous owner, or as a factory experiment or prototype. Because
this rig was already non-standard, I made the changes to upgrade
it to be functionally equivalent to the SR-500. Walt Cates (who
replied to you earlier and whom I consider the expert on these
rigs) had put together a list of differences/changes between the
two rigs.
As I only have the one power supply
(which works for either rig), I don't want to break up the set.
By the way, I also have an SR-2000 and
matching P-2000 power supply. All of these are great rigs, even by
today's standards (especially for someone who likes to fiddle with
real knobs instead of a computer screen).
Like you, I started in ham radio early
in life, getting my novice license in 1957 at the age of 12
(KN7DYB). Since then, I have been in and out of ham radio
depending upon the demands of real-life. When I retired from the
computer industry, I had enough time (and money) to nurture my
interests in vintage tube-type ham radios. I am more of a restorer
and tinkerer rather than operator, although I do get on the air
occasionally, mostly to check out whatever project I am working on
at the time.
If you are interested, I can send you
more information (photos, etc.). My email is good on QRZ.com.
Bob,? K7DYB
On 2/19/2025 1:21 AM, Scott WA9WFA via
groups.io wrote:
Hi, Lately I’ve been waxing nostalgic about the old Hallicrafters transceivers. ?A friend loaned me his SR-160 for several months back in 1971 while I was in Senior in High School and I used it for that summer before heading off to the Vietnam War. ? It was a wonderful transceiver! ?
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Re: SX-28A Hum
开云体育Thanks Jacques, well that seems to pour cold water on the magnetic coupling theory. If the trace I copied is typical {I don’t know}… ie; assuming? that hum is 60 cps with third harmonics at /I n /close to the choke, there can be electrostatic coupling by close parallel wires from AC incoming wires being too close to the? choke ??wires. ??? Moving stuff might mean moving wires and coupling. I worry more about long wires running to the switch. ?Another long shot.? … but the old stories of just moving stuff raises its head. I’m dried out. ? From: [email protected] [mailto:[email protected]] On Behalf Of Jacques_VE2JFE via groups.io
Sent: Wednesday, February 19, 2025 3:04 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-28A Hum ? In a SX-28A, the CH2 is as far as it can be from the power transformer: ? ? ? The black “core” at the left is the CH2. You can see the bottom of the power transformer and the filtering choke at right. The closest transformer to the CH2 is the audio output. ? ? 73, Jacques, VE2JFE in Montreal ? De?: [email protected] <[email protected]> De la part de don Root ? Tom and/or anybody still tuned in. Still looking for what really failed and how. For anyone wondering about the details and possible source, I copied a bit of your first Video so I could take a closer look. I see 60 Hz and strong third harmonics, and no visible high harmonics. It reminds me of core saturation. Power transformer magnetics and primary is the only source I can think of. Any comments?
_._,_._,_ -- don??? va3drl |
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Re: SX-28A Hum
开云体育In a SX-28A, the CH2 is as far as it can be from the power transformer: ? ? The black “core” at the left is the CH2. You can see the bottom of the power transformer and the filtering choke at right. The closest transformer to the CH2 is the audio output. ? ? 73, Jacques, VE2JFE in Montreal ? De?: [email protected] <[email protected]> De la part de don Root ? Tom and/or anybody still tuned in. Still looking for what really failed and how. For anyone wondering about the details and possible source, I copied a bit of your first Video so I could take a closer look. I see 60 Hz and strong third harmonics, and no visible high harmonics. It reminds me of core saturation. Power transformer magnetics and primary is the only source I can think of. Any comments?
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Re: SX-28A Hum
开云体育Tom, if I recall it was not fastened to the chassis… at least in the same way. ?If the power transformer is near by the choke, it’s flux can/might? use a bit of the chassis and the choke could pick it up from the flux in the chassis. For that I would try removing steel fastening on one hold down point or both and grounding the core for safety at one point only or separately.? You could Put a little space under the choke as a test? ? But it is also possible that wires from the on/of switch run too close to the BASE ?switch. ? If you want more stable scope traces sync to the “line” or whatever it might be called now. ? From: [email protected] [mailto:[email protected]] On Behalf Of thoyer via groups.io
Sent: Wednesday, February 19, 2025 12:52 PM To: [email protected] Subject: Re: [HallicraftersRadios] SX-28A Hum ? Interesting Don........ ? When I replaced the choke, CH2, this all went away so I don't know how it would be related to the power xfmr? ? Tom ? On Wednesday, February 19, 2025 at 12:31:39 PM EST, don Root <drootofallevil@...> wrote: ? ? Tom and/or anybody still tuned in. Still looking for what really failed and how. For anyone wondering about the details and possible source, I copied a bit of your first Video so I could take a closer look. I see 60 Hz and strong third harmonics, and no visible high harmonics. It reminds me of core saturation. Power transformer magnetics and primary is the only source I can think of. Any comments?
-- don??? va3drl |
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Re: SX-28A Hum
开云体育Tom and/or anybody still tuned in. Still looking for what really failed and how. For anyone wondering about the details and possible source, I copied a bit of your first Video so I could take a closer look. I see 60 Hz and strong third harmonics, and no visible high harmonics. It reminds me of core saturation. Power transformer magnetics and primary is the only source I can think of. Any comments?
-- don??? va3drl |
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Re: SR-500 Tornado
开云体育
Hi Scott,
The Tornado (SR-500) is an excellent tri-bander. It is a single conversion receiver that performs better than a lot of dual?conversion rigs. With its 250 to 300 watt output it will punch through the noise. The SR-500 is actually an SR-160 with a beefed up
PA subsystem and a power supply providing higher voltages.
The 8236 tubes ARE a problem. Although these are magnificent tubes, with solid carbon block plates, they do occasionally go bad. There are not many good sources for them. When you do run across them there is no guarantee that?they will be matched. Matching
is key to proper operation of the PA.?
The 6DQ5 is a direct replacement for?the 8236. There is a problem with the height of 6DQ5. They come in various?sizes and even with the shortest tubes you need to dimple the PA gage cover.?
The final Achilles heel is the vfo. The 500, like all the SR series rigs, are three times older than the shelf life of its temperature compensating capacitors. This is not a difficult problem to solve, replace C129 NPO and C133 N470.
I hope I have not scared you off the quest for a Tornado. But all ventage rigs require a little TLC.
I have written a repair manual for the SR-500 Tornado. It is a no cost download at:
Good luck with your quest, 73.
Walt Cates, WD0GOF
?
From: [email protected] <[email protected]> on behalf of Scott WA9WFA via groups.io <whitebear1122@...>
Sent: Wednesday, February 19, 2025 12:21 AM To: [email protected] <[email protected]> Subject: [HallicraftersRadios] SR-500 Tornado ?
Hi, Lately I’ve been waxing nostalgic about the old Hallicrafters transceivers. ?A friend loaned me his SR-160 for several months back in 1971 while I was in Senior in High School and I used it for that
summer before heading off to the Vietnam War. ? It was a wonderful transceiver! ?
The premium Hurricane, Cyclone, and Tornado have fascinated me for many years but I never pursued them during my collecting years. ?The collecting years are long over and I’ve sold 99% of my collection with only a few left, but I’m still
intrigued by those premium Halli transceivers.?
Maybe I need another one just to enjoy the nostalgia it gives.?I’m thinking of buying a Tornado for my one last remaining SSB tube transceiver.
The Hurricane and Cyclone scare me in terms of big size and complexity of repair. ?What about the Tornado? ?Do you Tornado owners find them easy or hard to repair? ?Are final amplifier tubes available or do you have to rewire
the socket for something else? ?
What do you Tornado owners think of them? ? Do you know of any working one’s for sale?
Thanks. ?73, Scott WA9WFA
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don Root
Jim Whartenby
Jacques_VE2JFE
Emanuele Girlando
Robert Kembel
waltcates