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Re: SR-150 and SR-160 QRO modifications
Last year I turned the rig on and the band sounded in really poor shape but there was a station calling CQ and I answered and worked him. Afterwards I realized why the band was quiet. I was on the dummy load and the other station was about 1500 miles away! Who needs QRO?? 73 Don ve3ids? On Mon., Feb. 24, 2025, 6:50 p.m. edward schumacher via , <eddiewa9gqk=[email protected]> wrote:
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Re: SR-150 and SR-160 QRO modifications
On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
I would tend to agree.
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If I am not mistaken,? the SR 500 in good repair and alignment would presumably do somewhere around 250-275W PEP output based on operating it at 500W PEP input.
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My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
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The difference between 150w (approx 52dBm) and 275W (54.4dBm) is not even 3dB total making it an essentially un-detectable difference on the other end.
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And even if you're going from 100W to 300W (50-54.8dBm) it's less than a 5dB difference, which is also not very significant on the other end.? To me, it doesn't really seem worth it to "butcher" the radio to make it happen.?
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Most of the fun I have using my HT44, HT32B and? SR400 (and even the HT33 Mk I, HT45 Mark IIA)? is the simple joy of operation in good band conditions.? When I mention I am using them, it generates all sorts of fun conversation about them vs how strong the signal is!
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73/Rick W7IMM __________________________________ All posts are created using free and opensource? Linux |
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Re: SR-150 and SR-160 QRO modifications
On Mon, Feb 24, 2025 at 05:28 AM, Robert Kembel wrote:
The comparison of horizontal sweep tubes vs the 6146 should probably include mentioning the fact that the vacuum tube manufacturers did not use CCS/ICAS ratings for nearly all the? sweeps (some exceptions)? because they weren't tested for those types of service. (that of course did not mean they wouldn't work!)
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The CCS? plate dissipation rating of an RCA 6146/6146A is? 20W.? (27W for a 6146B/8298A)?
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Collins, Heath, Hallicrafters (to name a few) designed their transmitters using the 6146 to put out about 100W (staying approx? within the ICAS ratings [25w ea] for a pair of them
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For comparison, the plate dissipation of a 6JB6 horizontal sweep tube (used in the Drake T-4X, TR-3[12JB6], TR-4, TR-6, TC-6) is 17.5W? (A whole 2.5W difference vs the 6146)
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Some had more dissipation.... The 6DQ5 for example in our beautiful HT-44's,? has 24W plate dissipation etc....
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That would make the 6DQ5 "better" than a 6146/6146A I would think.
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Now having said that,? the original 6146 had 20W CCS dissipation, what would the 6DQ5 have if it was rated CCS?
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I would submit that because horizontal sweep tube service actually is "CONTINUOUS"? (I.E, your TV was turned on in the morning and maybe not turned of until 18-24hrs later? (OR not turned off at all!!)? (wake up in the wee hrs of the morning to "snow" on the screen!!)
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That's about as continuous as it gets!.....so the 6DQ5 would have 4w more dissipation vs a "CCS" 6146/6146A
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Now, I will concede that Hallicrafters, Drake, Swan and all the others did indeed design and suggest operating sweeps at much higher peak power than would even be possible with? 6146s and included cautions to not "key-down" for too long...... But,? I don't think 6146's would fare any better than any sweep tube if abused at greatly higher power levels.
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Now to get back to the original (opinion) discussion, I really am with a few others here in that increasing the power output of an SR160 or an SR150? (even double [3dB])? is simply not worth the effort.
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Get a linear amplifier.
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By the way, I am looking for a REALLY nice SR-150 to put next to my Loudenboomer if someone wants to part with one! (It cannot look like it was stored in someones leaky-roof garage though)
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73/Rick W7IMM __________________________________ All posts are created using free and opensource? Linux |
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Re: SR-150 and SR-160 QRO modifications
开云体育
We shouldn't loose sight of the original topic, which was the use of the 6DQ5
in place of?the 8236. The 6DQ5 has a plate dissipation of 24?watts and transconductance of 10.5K. The 6DQ6 is 18 watts and 7.3K.
Two interesting tubes on the chart which I have not considered or explored are the 6JE6 and the 6JF6, 30 watts and 10.7K. I think I have some in my treasure boxes, may have to investigate them.
Has anyone played with either of these tubes?
Walt Cates, WD0GOF
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Re: SR-150 and SR-160 QRO modifications
开云体育Hi all,
As I recall, there was a bit of a
"horsepower" (er, Peak Envelope Power - PEP) thing going on during
the late 60s and 70s where manufacturers focused on the 'peak'
power (PEP) rather than average power or CW power. It was also a
time when TV sweep tubes were inexpensive and if pushing the power
a bit resulted in a shorter tube life, so be it. The plate
dissipation of the 6DQ6/12DQ6 is only 18 watts, so figuring a
typical efficiency of 50% to 60% for class AB1 operation, the "key
down" power would be limited to about 70 watts input for a pair of
tubes. Fortunately most ham operation is not continuous key down
and we are able to get away with more peak power. One common
assumption for SSB operation is that the peak power (PEP) is about
twice the average power (the duty cycle is about 50%). Given this,
a pair of these tubes could conservatively be used at about
140-150 watts input without stressing the tubes. The intended
application for the sweep tubes as horizontal output tubes in TV
requires high peak power (plate current), while the average
dissipation is significantly lower. I have attached a small file
comparing the ratings of several of the sweep tubes used in ham
and CB equipment during this time frame. Note that the largest
plate dissipation is about the same as the venerable 6146B at
around 30 watts. The difference is that the 6146 is designed for
continuous duty operation vs. low duty cycle operation. A number
of hams have been bit by not being aware of power requirement when
using modes that are in fact 100% duty cycle such as RTTY and (I
think) FT-8.
I suspect the use of PEP was mostly a
marketing statement intended to provide a simple number that could
be used to compete against other manufacturers using PEP in their
advertising, much as we see the same thing today in marketing 1kw
amplifiers vs 1.5kw amplifiers. The difference is less than 1/2 of
an "S" unit but, golly, its 50% more power.
Anyhow, almost all of these tubes are
getting harder to find and more expensive as the existing supplies
gradually dry up...
Bob,? K7DYB
On 2/23/2025 1:36 AM, HF via groups.io
wrote:
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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,? you can’t get away with this without doing a post-mortem for the benefit of? many many others that might go down your road starting where you started. [Smiley-face here] The coax has nothing to do with your original alignment problems? Right ? In the event that the trimmers are far off the needed values, just maybe C3 and C4 ?interact a bit, lulling them to a small false peak [somehow] and trapping you there.? Early on I was trying to encourage you to set the trimmers near max and start again. You had test/alignment gear and could not get it “unstuck”? but would have pre-tuned it properly had it not been for that coax? Now that it is aligned, how is the sensitivity? And how does the V1-V2 get coupled. Are we down to the invisible gimmick in the band switch? ? From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io
Sent: Sunday, February 23, 2025 9:29 AM 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! ? MEA CULPA ?_._,_ -- 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!
开云体育Hello Emanuele, So my intuition was right. Happy to know that all is good with your S-85 now. Case closed ! ? 73, Jacques, VE2JFE in Montreal ? MEA CULPA!!? SORRY!! SORRY!! SORRY!! SORRY!! SORRY!!? ? As Jacques suggested I had to double check the measuring setup. Nothing strange in there but a leap of imagination on my part: for convenience I connected the probe tip to the sample point via 15cm of coaxial cable. By removing that cable and positioning the tip of the probe very close to the sampling point, all the numbers immediately turned out to be spot on where they had to be. So, no bad or wrong parts. ? I was also been able to isolate the "sudden signal level decrease" problem: it's a fault in the TG circuit of my Spectrum Analyzer. So the cleaning the spring contacts of C7 I performed yesterday, even if did some good anyway, had nothing to do with that problem. ? Reconnecting C33 to the V1 grid dropped the peak frequency a bit, but I was able to easily recover it to the correct values by slightly tweaking the TRIMCAPs. So, with this setup, in order to bring C3 and C4 close to the alignment points, I tweaked them so that the peaks are (visually) located exactly on the frequencies required by the alignment procedure (a sort of "prealignment" procedure). ? Then I turned the rig ON and performed an accurate alignment as per service manual. Everything went well with no further problems. ? My conclusion is that some previous owner played with the tuning without any test gear and screwed it up in all stages and completely. With my "prealignment" procedure, done using the spectrum analyzer, I brought things closer and closer to where they had to be, allowing me to perform the final alignment as per service manual without any further problem. ? Once again: SORRY for my mistakes, .. many mistakes! I can declare this post CLOSED and problem SOLVED. ? THANK YOU VERY MUCH INDEED TO ALL YOU GUYS!!!!!!!!!!!!!!!? -- Emanuele (IU1KNR). |
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Re: SX-117 Power transformer Voltage
开云体育Hello Wolfgang, From the schematic and the “normal” voltages chart in the SX-117 manual, the primary +B voltage at C117B looks to be 200V. Which means a transformer HV secondary of 280Vct (140-0-140). There is also a replacement transformer specified in the attached document, but the secondary voltage rating seems to high, IMHO. ? 73, Jacques, VE2JFE in Montreal ? Hello, I am restoring a SX-117. A former owner replaced the original transformer by a transformer with a primary voltage of 220 Volt. The secondary voltage of this transformer is much too high. I would like to know if there is any info on the secondary voltage of the original transformer as I am looking for getting a replacement. 73s Wolfgang dk7cy |
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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!
MEA CULPA!!? SORRY!! SORRY!! SORRY!! SORRY!! SORRY!!?
?
As Jacques suggested I had to double check the measuring setup.
Nothing strange in there but a leap of imagination on my part: for convenience I connected the probe tip to the sample point via 15cm of coaxial cable.
What a mistake!! By removing that cable and positioning the tip of the probe very close to the sampling point, all the numbers immediately turned out to be spot on where they had to be.
So, no bad or wrong parts.
?
I was also been able to isolate the "sudden signal level decrease" problem: it's a fault in the TG circuit of my Spectrum Analyzer. So the cleaning the spring contacts of C7 I performed yesterday, even if did some good anyway, had nothing to do with that problem.
?
Reconnecting C33 to the V1 grid dropped the peak frequency a bit, but I was able to easily recover it to the correct values by slightly tweaking the TRIMCAPs.
So, with this setup, in order to bring C3 and C4 close to the alignment points, I tweaked them so that the peaks are (visually) located exactly on the frequencies required by the alignment procedure (a sort of "prealignment" procedure).
?
Then I turned the rig ON and performed an accurate alignment as per service manual.
Everything went well with no further problems.
?
My conclusion is that some previous owner played with the tuning without any test gear and screwed it up in all stages and completely.
With my "prealignment" procedure, done using the spectrum analyzer, I brought things closer and closer to where they had to be, allowing me to perform the final alignment as per service manual without any further problem.
?
Once again: SORRY for my mistakes, .. many mistakes!
I can declare this post CLOSED and problem SOLVED.
?
THANK YOU VERY MUCH INDEED TO ALL YOU GUYS!!!!!!!!!!!!!!!
?
?
--
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!
Since you are having strange problems I would suggest not trusting rivets to make a good ground connection.? Much better to solder the riveted grounds to the chassis at the tube sockets and the single ground point near the wafer switch.?? There appears to be ample room as shown in Jim's photos to get a large 100 or so watt soldering iron in there to solder the ground terminals to the chassis.? Nokorode solder paste works well for me.? A little fine grit sandpaper held by a hemostat to roughen up the area would help prepare the joint for soldering. Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
On Saturday, February 22, 2025 at 04:01:20 PM CST, JThorusen <jthorusen@...> wrote:
Hi Emanuele!
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?? It takes me a bit of time to respond to these things... I had a serious fall in January and broke my back in 3 places so I am hobbling around in a back brace and cannot lift anything myself, but must get my care giver to do it.?? However, it has been done; here are the results:
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I hope this is of some help.?? I am not able to take the radio any further apart at this time.
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73,
--
Jim T.
KB6GM |
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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Hi Emanuele, I do not understand why the measurement of the L3 and C7A values can be good and the combination of the two so wrong. The only thing I do not see correct in your setup is the use of the RTMA “dummy” antenna which can screw up the whole measurement setup by adding more parallel capacitance to the whole circuit. If you try to measure one of the L3 sections ALONE with the C7A parallel capacitor + trimmer the results HAVE TO BE DIFFERENT. OK for the active fet probe, but those things are not magical and often present an input impedance lower than a 10:1 low cap probe. Which model of fet probe are you using ? The signal source used to measure the parallel resonance should have a resistive only impedance at least 100 times more high than the reactance of the coil or the capacitor, and this is why I put a 100k ohms in the setup I suggested to use. Using a SA as the signal source is OK, I think, but just try a scope with a low cap probe instead of the fet probe, just to see if there is a difference. ? It just makes no sense that the whole parallel resonant circuit, when measured, performs that way off compared to what it should. ? 73, Jacques, VE2JFE in Montreal ? Jacques, I repost the measuring setup: The RF probe is an with 1500MHz bandwidth. Do you see anything wrong here? please let me know! I repeat that actually C33 has been disconnected from V1 pin4 and the probe moved to the now free terminal of C33 so that the ANT circuit has become completely standalone. I also tried to change the antenna connection between the following configurations: RTMA, a 0.01uF cap, pure induction (air): the signal levels change, but the peaks are steady at the wrong too low values. C7 and L3 were measured out of circuit using a DE-5000 LCR meter. If everything is ok as I suppose it to be, your question remains unanswered: where does the excess capacitance come from? I can only think of wrong parts or a miswiring problem. ? Jim, thank you very much indeed for your effort! I am going to have a close look at your pictures tomorrow. First impression: your radio is much better preserved than mine! ? I have a news: during today's tests I saw the signal going up and down for no apparent reason, without me doing anything. Also, when going up and down in band 1 by rotating the main tuning knob, the signal showed a significant drop in the lower half of the band (something I had never seen before). This gradual increase in contact resistance as the tuned frequency decreases could explain the problem of the significant decrease in sensitivity the radio shows at these frequencies. ? Unfortunately, the effect of the hidden capacitance has remained the same. I think I have to tear C7 down and bring it somewhere to give it an ultrasonic treatment. -- Emanuele (IU1KNR). |
don Root
Don VE3IDS
Rick W7IMM
waltcates
Robert Kembel
Jacques_VE2JFE
Emanuele Girlando
Jim Whartenby