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Re: For Sale - Hallicrafters R-274/FRR with speaker

 

Dwight, I like that counterweighted roof setup. I've never seen anything like that. It gives you great low angle viewing! The roof on my primary observatory is motorized so it tracks on rails but the room has 8' ceilings and requires a Pier 2 to lift the OTA. This works ok but I would much rather have a setup like yours. It does allow me to roll the roof back and remotely operate the scope from Houston. It's set up with OAK control hardware so if a storm sneaks up, the skycam senses the weather, closes the roof and shuts things down until the weather passes unless you run into daylight. I've got one of the original AP 6" that I use on a portable mount. I also have a 10" f4.5 that I ground polished and figured when I was a kid. I built an alt-az mount for it and still use it on occasion on the deck while running the other gear.
?
The other observatory with the dome is located on a regional hill and makes the most of the incredible Bortle 1 skies in our area. The dome isn't motorized so during the course of the night you have to manually push the dome. It's a 10' fiberglass dome and doesn't like to be pushed. I have a 12" RC at that location and eyepiece astronomy is my favorite. It also has an AP 1200 mount but it's not goto like yours. That hasn't been a problem for me because I'm on the eyepiece and not the camera.
?
If the last picture is your current setup in ABQ, you aren't hurting too bad. LOL Very nice equipment and I especially like the AP 1200.
?
I didn't totally dodge the bullet in the service. I enlisted in the Navy Seabees and went to boot camp at Great Lakes. I got on the plane in late November in Baton Rouge wearing a long sleave shirt at 80 degrees. I wore a long sleeve shirt because I was told it might be colder up north. I got off the plane in Chicago and determined I had made a tactical error. When I left the building and found a cab to take me to the Great Lakes Naval facility, I determined just how large a tactical error I had made. The next 2 1/2 months were not meant for people much less a coonass from south Louisiana. I'm not sure what the ambient temp was that winter but I do know the wind chill in 40mph winds is brutal. On top of that Vietnam caused an overload with the barracks and we spent the 1st month in the wooden WW2 barracks that had very little steam radiator heat and no running water. We had to march to the chow hall and showers daily. The military was great with the Seabees but the Navy boot camp, not so much.??
?
Tom
N5AMA
Re: S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1?

 
Edited

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Emanuele ?

Yes, I prefer to look at R26 and C29 as the plate load Impedance, so the V1 output voltage is developed thru it, and as you reiterated there is no V1-V2 obvious intended coupling in band 1, but the switch has inherent capacitance across the wafer and perhaps that is enough, as your tests seem to indicate.

Any yes R65 is probably to reduce overload tendencies on the BCB.

?

Recall that C62 began with the S-40A [not the same spot] , and perhaps the S-40?

?

From: [email protected] [mailto:[email protected]] On Behalf Of Emanuele Girlando via groups.io
Sent: Wednesday, February 26, 2025 12:46 PM
To: [email protected]
Subject: [HallicraftersRadios] S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1?

?

This topic raised in the "TRIMCAPs don't peak" thread.

I think it's worth its own thread. Here it is.

?

In the S-85 there is no obvious coupling between the RF amplifier tube (v1) and the MIX/OSC tube (v2) in band 1.

The output of V1 seems to get lost in the R26/C29 couple.

?

Someone argued that the signal path could go through the S1B wafers.

Other argued that there is some other stray coupling in the circuit wiring.

Someone noted that the S-40B has an identical circuit but it is equipped with an additional capacitor (C62), positioned just between the V1 output and the v2 input.

The following picture sketches the S-85 circuit with the possible signal path and the phantom C62 highlighted.

?

?

?

So I've made some measurements on my S-85.

Using my 9640B sig-gen connected to the ANT A2 input via a RTMA dummy antenna (A1 shorted to GND),

AM modulated at 30%,

I got the following:

Below the indicated value the signal gets lost in the noise.

As you see I also made a test shorting R65 in the input circuit as someone argued that it could impact (as it does) the receiver sensitivity in the higher part of band 1.

?

Thoughts?

--

Emanuele (IU1KNR).


--
don??? va3drl
Re: For Sale - Hallicrafters R-274/FRR with speaker

 
Edited

Nice looking setup.? I love New Mexico for the landscape.? You don't see this on the east coast. My step-son lives in Houston. We have driven there a couple of times and know it is a long trip. We stop for the night in Fredericksburg TX and stay at a friend's place.?
?
Be glad you were not in the military with me. My first assignment was in upper Michigan, where the temps would fall to -60 degrees.??
Here is a shot of my observatory when I lived north of Albuquerque.? It is a DobHut that I converted to my use. It held my main two scopes and I had a pier behind it for my long scope. But I got sick and had to sell the obs and house and move into ABQ to a single story house.? I get some good nights here, so can't complain.?
Dwight
?
S-85: how are the RF amplifier tube (v1) and the MIX/OSC tube (v2) coupled in band1?

 
Edited

This topic raised in the "TRIMCAPs don't peak" thread.
I think it's worth its own thread. Here it is.
?
In the S-85 there is no obvious coupling between the RF amplifier tube (v1) and the MIX/OSC tube (v2) in band 1.
The output of V1 seems to get lost in the R26/C29 couple.
?
Someone argued that the signal path could go through the S1B wafers.
Other argued that there is some other stray coupling in the circuit wiring.
Someone noted that the S-40B has an identical circuit but it is equipped with an additional capacitor (C62), positioned just between the V1 output and the v2 input.
The following picture sketches the S-85 circuit with the possible signal path and the phantom C62 highlighted.
?
?
?
So I've made some measurements on my S-85.
Using my 9640B sig-gen connected to the ANT A2 input via a RTMA dummy antenna (A1 shorted to GND),
AM modulated at 30%,
I got the following:
Below the indicated value the signal gets lost in the noise.
As you see I also made a test shorting R65 in the input circuit as someone argued that it could impact (as it does) the receiver sensitivity in the higher part of band 1.
?
Thoughts?
--
Emanuele (IU1KNR).
Re: For Sale - Hallicrafters R-274/FRR with speaker

 
Edited

Hi Dwight,
I've attached a few pics of the Pie Town setup. Actually, it's two sites. One is a rolltop with a connected warm room. The other is a hill top site with a typical dome and an incredible view of the horizon. The views in the area are spectacular. I think you would enjoy a visit.
?
Tom
Re: For Sale - Hallicrafters R-274/FRR with speaker

 

Hey Dwight,
Thanks for the email. FB on your Rio Rancho observatory. As you might guess, I’m not up there every weekend for several reasons. It’s a 17 hour drive one way for me from Houston. Another reason is I’m a coonass from south Louisiana and 5 degree temps in the winter don’t work well for me. Next time I go up, I’ll be glad to give you a heads up, meet you there and show you around. I’m on the IPad right now but will post you a few pictures when I get on the desktop.
?
Pie Town does have a restaurant that serves good pies but I’m not sure they are open every day. Once there were two places that served pies across the street from each other but they swapped open days because there really wasn’t enough business to support two open at the same time.
?
Tom N5AMA
Re: SR-150 and SR-160 QRO modifications

 

Rick W7IMM,
If you would please contact me offline.
73/Randy WN9D
Re: For Sale - Hallicrafters R-274/FRR with speaker

 

Hey Tom.? I had an observatory in Rio Rancho for a while.? I would love to see your setup.? My wife and I went to Pie Town once and they did not have any pies.? WTF!!!
?
Let me know when you are going to be in the area.?
?
Dwight.?
?
?
Re: SR-150 and SR-160 QRO modifications

 

For several years during the 1970s my only rig was a Heath HW-7 running
3 watts with which I worked over 30 states on 40 CW using an attic
dipole. Lots of fun. You can't work everyone you hear with QRP, but
patience helps.

73,

Maynard
W6PAP


On 2/24/25 15:50, edward schumacher wrote:
And for proof of the power theory (fact) I just completed a cw Q to Wake
Island over the weekend accidentally driving my Acom 1500 which was till
tuned for 15M while having the K4 set for 100W drive on 12M. Made the
contact in one call and then noticed I had not thrown my antenna
switches to go 'round the amp. My forward power with this mixup was _3W_.

Confirmed this by going up freq and keying and sure enough, my inline
wattmeter was barely moving attesting to genuine QRP. I received a 559
from Wake.

The lesson, don't need to burn the rig for a few more watts.

Ed, WA9GQK

On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via
groups.io <myr748@...> wrote:


On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:

*We shouldn't loose sight of the original topic, which was the use
of the 6DQ**5 **in place of?the 8236. *
**
**
*Walt Cates, **WD0GOF*
*_ <> _*
*A majority of acceptance is not proof of correctness. *
*
<>**
*

I would tend to agree.
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.
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP
output.
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.
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.
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!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
Re: SR-150 and SR-160 QRO modifications

 

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That Dummy is not so dumb?

?


--
don??? va3drl
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:
And for proof of the power theory (fact) I just completed a cw Q to Wake Island over the weekend accidentally driving my Acom 1500 which was till tuned for 15M while having the K4 set for 100W drive on 12M. Made the contact in one call and then noticed I had not thrown my antenna switches to go 'round the amp. My forward power with this mixup was 3W.

Confirmed this by going up freq and keying and sure enough, my inline wattmeter was barely moving attesting to genuine QRP. I received a 559 from Wake.

The lesson, don't need to burn the rig for a few more watts.

Ed, WA9GQK

On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via <myr748=[email protected]> wrote:


On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.

?
I would tend to agree.
?
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.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
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.
?
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.?
?
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!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
Re: SR-150 and SR-160 QRO modifications

 

And for proof of the power theory (fact) I just completed a cw Q to Wake Island over the weekend accidentally driving my Acom 1500 which was till tuned for 15M while having the K4 set for 100W drive on 12M. Made the contact in one call and then noticed I had not thrown my antenna switches to go 'round the amp. My forward power with this mixup was 3W.

Confirmed this by going up freq and keying and sure enough, my inline wattmeter was barely moving attesting to genuine QRP. I received a 559 from Wake.

The lesson, don't need to burn the rig for a few more watts.

Ed, WA9GQK

On Monday, February 24, 2025 at 03:40:49 PM CST, Rick W7IMM via groups.io <myr748@...> wrote:


On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.

?
I would tend to agree.
?
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.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
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.
?
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.?
?
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!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
Re: SR-150 and SR-160 QRO modifications

 

On Mon, Feb 24, 2025 at 06:53 AM, waltcates wrote:
We shouldn't loose sight of the original topic, which was the use of the 6DQ5 in place of?the 8236.
?
?
?
Walt Cates, WD0GOF
?
A majority of acceptance is not proof of correctness.

?
I would tend to agree.
?
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.
?
My HT44 with the stock PS-150-120 seems to work well at about 150W PEP output.
?
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.
?
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.?
?
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!
--
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
Re: SR-150 and SR-160 QRO modifications

 

On Mon, Feb 24, 2025 at 05:28 AM, Robert Kembel wrote:
.........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.
?
?
Bob,? K7DYB
?
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!)
?
The CCS? plate dissipation rating of an RCA 6146/6146A is? 20W.? (27W for a 6146B/8298A)?
?
?
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
?
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)
?
Some had more dissipation.... The 6DQ5 for example in our beautiful HT-44's,? has 24W plate dissipation etc....
?
That would make the 6DQ5 "better" than a 6146/6146A I would think.
?
Now having said that,? the original 6146 had 20W CCS dissipation, what would the 6DQ5 have if it was rated CCS?
?
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!!)
?
That's about as continuous as it gets!.....so the 6DQ5 would have 4w more dissipation vs a "CCS" 6146/6146A
?
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.
?
?
?
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.
?
Get a linear amplifier.
?
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)
?
?
?
73/Rick
W7IMM
__________________________________
All posts are created using free and opensource? Linux
Re: SR-150 and SR-160 QRO modifications

 

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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
?
A majority of acceptance is not proof of correctness.


Re: SR-150 and SR-160 QRO modifications

 

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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:

(Since this is a diversion from the original topic (SR-500 Tornado), I assigned a new topic.)
Thanks, Bob and Walt,
Since the SR-160 and SR-150 both use 12DQ6B finals, wouldn't the sockets be the same and the same rewiring of sockets be required?? On further examination of the 2 radios' schematics, I see that the circuits around the finals are a little different, so maybe there would be some additional changes needed there, too.?
I agree that the potential performance benefit would be small.? That half of an S unit was, apparently, sufficient for some hams to buy an SR-500 instead of an SR-160 a several decades ago.? Maybe it was just a bigger number on the front panel or the invoice.?
Cheers
Halden


Sweep Tube Specifications.pdf
Sweep Tube Specifications.pdf

Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!

 

Hi, Emanuele,

I hope that you get as much enjoyment from your S-85 as I do from my S-40B.

But Don brings up some interesting thoughts. We might all learn
something from all of this. At one point you installed a "gimmick" to
simulate C62 from the S-40B. I don't recall you writing that you
removed it but maybe I just missed that. Is it still there?

73,

Maynard
W6PAP


On 2/23/25 12:26, don Root wrote:
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
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!

 

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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
Re: S-85 refurbish: I've got a problem during the RF alignment of bands 1 and 2 - trimcaps don't peak!

 

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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.
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).
Re: SX-117 Power transformer Voltage

 

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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

Harbach-Peter-Dahl-various-transformer-specifications.pdf
Harbach-Peter-Dahl-various-transformer-specifications.pdf

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