Re: S-40 Restoration - Oddity around V2
Thanks for the reply, Art.? Many old receivers never did very well on the upper bands -- possibly, it was an experiment to see if fiddling with the oscillator circuit would help.? Unless any other information arises, think I'll just restore it to factory.? I'm used to seeing a lot of modifications and (failed) experiments, but this one is quite a puzzle.??
73 - Steve, KW4H
|
Re: S-40 Restoration - Oddity around V2
Steve...
?
It looks like elimination of R30 would increase the Local Oscillator
injection level.? I’m not sure why this would be a good idea?
?
73,
ART
W6REQ
?
toggle quoted message
Show quoted text
From: Steven Reed via groups.io
Sent: Sunday, September 18, 2022 6:32 AM
Subject: [HallicraftersRadios] S-40 Restoration - Oddity around
V2
?
Glad
to have found this group!
I've got an S-40 on the bench -- a restoration
project for a friend.? The receiver belonged to his grandfather (who was
licensed), then was passed on to him.? For the most part, the receiver
appears to be all factory, which is always helpful.? However, his
grandfather had been into the radio, and I've found a circuit alteration on V-2
that I'm uncertain about.? This is a 2nd revision model of the S-40, by the
way.?
The
attached schematic shows V-2 and the area around it as originally designed by
Hallicrafters.? Have a look at pin 5 (grid #1) -- the alteration I'm seeing
is off of there.? Here are the changes:
-
R30 (10 ohms) is eliminated
-
C16 connects directly from pin 5 to S/IF
-
C26 connects directly from pin 5 to ground
So,
the modification puts three connections on pin 5 -- R7 to ground, C26 to ground,
and C16 to S/IF.
Before
deciding whether to revert this back to factory, I'm curious as to why this
might have been done.? I've searched online and can't find this
modification anywhere.?
73
- Steve, KW4H
|
S-40 Restoration - Oddity around V2
Glad to have found this group!
I've got an S-40 on the bench -- a restoration project for a friend. ?The receiver belonged to his grandfather (who was licensed), then was passed on to him. ?For the most part, the receiver appears to be all factory, which is always helpful. ?However, his grandfather had been into the radio, and I've found a circuit alteration on V-2 that I'm uncertain about. ?This is a 2nd revision model of the S-40, by the way. ?
The attached schematic shows V-2 and the area around it as originally designed by Hallicrafters. ?Have a look at pin 5 (grid #1) -- the alteration I'm seeing is off of there. ?Here are the changes:
- R30 (10 ohms) is eliminated
- C16 connects directly from pin 5 to S/IF
- C26 connects directly from pin 5 to ground
So, the modification puts three connections on pin 5 -- R7 to ground, C26 to ground, and C16 to S/IF.
Before deciding whether to revert this back to factory, I'm curious as to why this might have been done. ?I've searched online and can't find this modification anywhere. ?
73 - Steve, KW4H
|
Re: Repair switch of the SR400
|
Looking for a working SX-140 w/xtal calibrator in trade.
HA-10 photo attached.
Regards,
bob...w2ami x wn2ami 1962
|
Re: FT-243 crystal holder
Thanks Bill- I? bookmarked that page years ago and had forgotten about it. The site construction reminds me of Dan’s Small Parts (now retired I understand). Anyway, I eventually found an eBay seller who has the brown sockets apparently brand new and very reasonably priced- they are to arrive today. I was also able to do repairs on 2 of my broken sockets and can send pix on the technique? to anyone interested. I am? going to order one of the Netty 40M rocks though- and grind it up a couple of Kc for my newly restored Lafayette HA-410 rig- it multiplies? 4X to? end up on 10M. ? Tnx, Dale W4OP ?
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|
Re: FT-243 crystal holder
Found this place may possibly have what you need.
K2WH
|
REDUCED! I have a very nice, operational SX-111 with matching speaker for sale. Recapped and new three pronged power cord installed. On air tested. Side by side tests with my FT1000d were very favorable. Both cabinets have been tastefully (albeit not professionally) repainted and look very nice. The only alteration I did was to remove the heating resistor for the VFO that I thought was very poorly mounted. The VFO is very stable after a short warmup without it. I will include it should the new owner wish?to re-install it. Manual included (original MK I, but is almost identical to the basic SX-111). $270 shipped to lower 48. USPS MONEY ORDER. OF COURSE NO WARRANTY EXPRESSED OR IMPLIED. ALL SALES FINAL.
|
Trent,
Tks, I'll drop it in the mail tomorrow also.
?Walt Cates,
WD0GOF
?
Your past has no control over your future. Only your NOW can impact your future.
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Show quoted text
Mine is well used. I’ll send it to
You for the 100w 200-500
I’ll put it in the mail
ToMorrow.?
trentfleming.com
On Sep 14, 2022, at 8:08 PM, waltcates <cateswa@...> wrote:
?
I am looking for a Bird 43 100W 2-30MC element.
Want to trade 1 for 1, I have duplicates of the following very used elements:
Bird 100W 25-60MC (Cover has been drilled to give access to the cal adjustment).
Bird 2.5W 95-150MC.
Bird 10W 100-250MC.
Bird 10W 200-500MHZ.
Bird 50W 200-500MC.
Bird 100W 200-500MC.
?SB? ?100W100-250MHZ
?Walt Cates,
WD0GOF
?
Your past has no control over your future. Only your NOW can impact your future.
|
Mine is well used. I’ll send it to You for the 100w 200-500
I’ll put it in the mail ToMorrow.?
toggle quoted message
Show quoted text
On Sep 14, 2022, at 8:08 PM, waltcates <cateswa@...> wrote:
?
I am looking for a Bird 43 100W 2-30MC element.
Want to trade 1 for 1, I have duplicates of the following very used elements:
Bird 100W 25-60MC (Cover has been drilled to give access to the cal adjustment).
Bird 2.5W 95-150MC.
Bird 10W 100-250MC.
Bird 10W 200-500MHZ.
Bird 50W 200-500MC.
Bird 100W 200-500MC.
?SB? ?100W100-250MHZ
?Walt Cates,
WD0GOF
?
Your past has no control over your future. Only your NOW can impact your future.
|
I am looking for a Bird 43 100W 2-30MC element.
Want to trade 1 for 1, I have duplicates of the following very used elements:
Bird 100W 25-60MC (Cover has been drilled to give access to the cal adjustment).
Bird 2.5W 95-150MC.
Bird 10W 100-250MC.
Bird 10W 200-500MHZ.
Bird 50W 200-500MC.
Bird 100W 200-500MC.
?SB? ?100W100-250MHZ
?Walt Cates,
WD0GOF
?
Your past has no control over your future. Only your NOW can impact your future.
|
Re: Calling all SX-100 Owners
Jim, ? That is exactly what the issue was, the dial was no seated properly.? And actually, I think the Pitch Control dial was seated a little too close to the front panel given that as you rotated the dial it will either move closer to or further away from the radio Face Plate.? So what I found is that there are 2 small rounded “bumps” that protrude from underneath the dial skirt that are exactly 180 degrees away from each other.? It appears the skirt was molded that way.? As I rotated the Pitch Control dial, those rounded bumps were dragging across the top of the protruding stop tab that comes off the front panel of the radio. ?I also found that there is a set screw in the Pitch Control shaft that protrudes from the shaft itself just far enough such that it will hit the stop tab as? you rotate the dial clockwise or counter clockwise. ?So It appears it is that tab along with that set screw that actually prevents you from rotating the Pitch Control more than +/- 150 degrees from the dial skirt 0 point.? Meaning if you seat the Dial properly it will not rotate past +/- 5 on the dial skirt.? So I reseated the dial a little further away from the Front Panel and aligned it such that it now rotates properly and stops at the +/- 5 points on the dial skirt.? At least those were my findings and solution for the SX-100 I have on the bench. ? Thank you, ? Mike W5CUL ?
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From: [email protected] < [email protected]> On Behalf Of JThorusen Sent: Tuesday, September 13, 2022 7:15 PM To: [email protected]Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners ? Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a variable inductor.?? It is capable of several turns either way from its ideal position.?? To index the control properly, there is a stop mechanism which is (again, as I recall) built into the knob.?? There is a combination of tang and milled slot that prevents rotation of the control more than 300 degrees or so.?? The "bump" you are experiencing is probably this stop mechanism and is due to the knob not being fully seated on the shaft, i.e. too far away from the front panel.?? If the "bump" is in the middle of the BFO range, then there is an alignment issue as well.?? Perform the BFO alignment as per the manual.?? Then install the knob centered and as close to the panel as it will go.?? You should now have a rotational limit at the extremes (+/- 5 on the knob skirt).??? Hopefully, the repetitive forcing of the knob past the stop has not worn the mechanism down to the point where it can no longer be made to function.
73,
--
Jim T.
KB6GM
|
Re: HT-32 Strange Behavior
What bands are you referring to?
Good Afternoon,
I noted that the upper and lower sidebands of my recently acquired HT-32 are reversed. Would anyone know ifs this a tuning issue? Crystal swapping issue? Or something else? Oddly, it seems to work fine if you place the sideband switch in the opposite mode. I am happy to do so,? if there are no other consequences.
73, Lou W2LTF
|
Looking for a SX-140 rx with xtal calibrator.
Have a Hallicrafters HA-10 LF Converter to trade.
Regards,
bob...w2ami x wn2ami 1962
|
Good Afternoon,
I noted that the upper and lower sidebands of my recently acquired HT-32 are reversed. Would anyone know ifs this a tuning issue? Crystal swapping issue? Or something else? Oddly, it seems to work fine if you place the sideband switch in the opposite mode. I am happy to do so,? if there are no other consequences.
73, Lou W2LTF
|
Re: Calling all SX-100 Owners
Mine is working very well. No problem to copy cw. Drift is a bit
noticeable on cw above 20mtrs but not too bad. I replaced all the
caps but the type that rarely go bad. Got my caps from Mouser.
There are several good websites to figure out which ones. And
replaced all the resistors with (mostly 1w and 2w) metal film
resistors. Bought the larger size version of metal film (near the
physical size of the carbons). The others just to tiny to look
right in this receiver IMO. As I got to checking carbon resistors
found out over half were out of tolerance so decided best to do
them all. Some may think that is overkill but in the end it is
your rig to do with as it pleases you. Biggest challenge was the
dog house but not that bad with patience. Redid the coax there
with RG-174. Took lots of pictures at various stages of
restoration. Lubed where appropriate with superlube. Deoxit where
appropriate. Spaghetti where appropriate. Aligned. Those things
took up the most time. Seems like I may have replaced a weak tube
or two, do not remember. Tested them all with my restored Hickok.
Only mod was the sensitivity pot to make the range more pleasing
to me. The chassis was not bad cosmetically. I first considered a
complete strip down, buff down, possible plating of the chassis
until I got to reading about the toxic coating on halli's, so just
give it sort of a sponge bath so to speak after removing easier to
remove items form the top side. A complete strip down would have
taken a boat load of time anyway.
73
Chuck
W4NBO
On 9/14/22 08:57, Mike wrote:
toggle quoted message
Show quoted text
So what I am hearing is replace all the
caps before making any voltage checks.? I do have the Hayseed
Cap kit in hand, so I will go ahead and get to work with that
along with checking resistor values as I go along.? Sounds
like in my excitement that it was actually receiving signals
pre-cap replacement I was getting ahead of myself.? Thank you
all for the advice.
?
As for the replacement resistor for R68, I
have several MEMCOR VL3 390 Ohm 3W wire wound resistors in my
junk box.? Understood it is an odd wattage rating, but they
are out there and I just happen to have several pulls in my
junk box all of which are less than 1% off value.
?
Thank you,
?
Mike
W5CUL
?
?
Check the grid
voltage, if it is too high (+) there will be too much
current drawn across the plate and cathode resistors,
usually caused by a bad coupling cap
The resistor is for grid bias. Check
the plate and screen voltages
?Actually, measure the resistor.
Composition resistors rend to go up in value.? ?That would
cause the drop across the resistor to go up.? It doesn't
hurt to have more dissipation.? 17V ACROSS 390V is about
0.7 watts so a one watt is marginal.? It will run hot
which will make it drift more.? I bet it's way off value.?
The larger resistor should be ok but 3 watts is an odd
value,? usually next size is 2 watts and then five watts.?
Check it's value before using it.? Also? , if there is a
bypass capacitor make sure it's ok.
? ?I think you are overdoing the VRiac
business? Of the filter caps don't short right away they
are probably not going to.? I assume this variac is
metered or you have some other means of watching for a
sudden rise in line current.
--------
Original message --------
Date: 9/13/22
6:51 PM (GMT-08:00)
Subject: Re:
[HallicraftersRadios] Calling all SX-100 Owners
Thank you Jim and All!!!
?
Very good information from everyone.?
This is certainly a haven of Hallicrafters Experts!!
?
Jim, I certainly hope that is the
issue as opposed to a bent shaft as was another
possibility mentioned by another gentleman.? I do not
relish digging the assembly out of its make shift can to
inspect the mechanics.? But if I must, then I must.
?
In the meantime, just for fun, before
any cap replacement, I put the receiver on a variac and
slowly brought it up watching for any of that magical
smoke to escape.? When I say slowly, I am talking about
advancing the variac 10 Vac every 15 minutes or so.? This
also helps in reforming some of those old caps along the
way, although I will be replacing all of them soon.? By
the time I hit roughly 40/50 Vac on the variac I could see
dial lights starting to perk up; so far so good.? When I
hit around 70 Vac or a little more I was hearing good
rushing noise coming out of the speaker; so far even
better.? I stopped at around 100 Vac and let it soak more
on that looking for that magical smoke, none smelt or
seen; just keeps getting better.? At that point, just for
fun once again, I attached an antenna to see if it can
receive on the BC bands.? Low and behold I was able to
tune in strong and some weak stations.? Next was 80M and I
was able to tune in some of the more stronger stations,
although the dials are off a little; wow looking really
good.? So after an hour of playing around, I started
creeping up to 110 Vac and let it sit for a little on
that.? By the time I hit 120 Vac, only 5 Vac from the
incoming line voltage to the house, that is when I could
smell the magical smoke; Houston we have a problem.? So I
let it sit for a while on that setting and let whatever it
was that was baking, although I kept a close eye and hand
on the transformer, finish cooking such that I could see
the magical smoke or at least a crispy component.? So the
culprit turned out to be R68, a 390 Ohm 1W resister in
line with the Cathode/Suppressor Grid of the 6K6GT audio
tube? A quick voltage check showed ~22.4 Vdc at that
point, yet the schematic shows it should be 17 Vdc.? So a
quick calculation indicated that the resistor was actually
dissipating ~1.25W of power with the radio sitting on 120
Vac, a little over what it is rated for.? I replaced it
with another 1W resistor for now and a new electrolytic
cap as well. Now I only move the Vac momentarily from 100
Vac to 125 Vac to check the voltage in the various other
areas to see what is really going on at todays higher
Vac.? In retrospect I will probably replace that resistor
with a 390 Ohm 3W pull I have in my junk box.? But I am
debating on whether to change the value to get closer to
17 Vdc when running the radio with 125 Vac input.? I have
seen a couple of designs showing a 500 Ohm used in the
same situation when faced with the same Plate and
Screening Grid voltages.? After a quick calculation 500
Ohms would drop it back to ~17 Vdc when running on our
normal home Vac voltages.? Decisions decisions.
?
Thank you,
?
Mike
W5CUL
?
?
Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a
variable inductor.?? It is capable of several turns either
way from its ideal position.?? To index the control
properly, there is a stop mechanism which is (again, as I
recall) built into the knob.?? There is a combination of
tang and milled slot that prevents rotation of the control
more than 300 degrees or so.?? The "bump" you are
experiencing is probably this stop mechanism and is due to
the knob not being fully seated on the shaft, i.e. too far
away from the front panel.?? If the "bump" is in the
middle of the BFO range, then there is an alignment issue
as well.?? Perform the BFO alignment as per the manual.??
Then install the knob centered and as close to the panel
as it will go.?? You should now have a rotational limit at
the extremes (+/- 5 on the knob skirt).??? Hopefully, the
repetitive forcing of the knob past the stop has not worn
the mechanism down to the point where it can no longer be
made to function.
73,
--
Jim T.
KB6GM
|
Re: Calling all SX-100 Owners
So what I am hearing is replace all the caps before making any voltage checks.? I do have the Hayseed Cap kit in hand, so I will go ahead and get to work with that along with checking resistor values as I go along.? Sounds like in my excitement that it was actually receiving signals pre-cap replacement I was getting ahead of myself.? Thank you all for the advice. ? As for the replacement resistor for R68, I have several MEMCOR VL3 390 Ohm 3W wire wound resistors in my junk box.? Understood it is an odd wattage rating, but they are out there and I just happen to have several pulls in my junk box all of which are less than 1% off value. ? Thank you, ? Mike W5CUL ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Scott Petersen Sent: Wednesday, September 14, 2022 4:48 AM To: [email protected]Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners ? Check the grid voltage, if it is too high (+) there will be too much current drawn across the plate and cathode resistors, usually caused by a bad coupling cap
The resistor is for grid bias. Check the plate and screen voltages ?Actually, measure the resistor. Composition resistors rend to go up in value.? ?That would cause the drop across the resistor to go up.? It doesn't hurt to have more dissipation.? 17V ACROSS 390V is about 0.7 watts so a one watt is marginal.? It will run hot which will make it drift more.? I bet it's way off value.? The larger resistor should be ok but 3 watts is an odd value,? usually next size is 2 watts and then five watts.? Check it's value before using it.? Also? , if there is a bypass capacitor make sure it's ok. ? ?I think you are overdoing the VRiac business? Of the filter caps don't short right away they are probably not going to.? I assume this variac is metered or you have some other means of watching for a sudden rise in line current. -------- Original message -------- Date: 9/13/22 6:51 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners Thank you Jim and All!!! ? Very good information from everyone.? This is certainly a haven of Hallicrafters Experts!! ? Jim, I certainly hope that is the issue as opposed to a bent shaft as was another possibility mentioned by another gentleman.? I do not relish digging the assembly out of its make shift can to inspect the mechanics.? But if I must, then I must. ? In the meantime, just for fun, before any cap replacement, I put the receiver on a variac and slowly brought it up watching for any of that magical smoke to escape.? When I say slowly, I am talking about advancing the variac 10 Vac every 15 minutes or so.? This also helps in reforming some of those old caps along the way, although I will be replacing all of them soon.? By the time I hit roughly 40/50 Vac on the variac I could see dial lights starting to perk up; so far so good.? When I hit around 70 Vac or a little more I was hearing good rushing noise coming out of the speaker; so far even better.? I stopped at around 100 Vac and let it soak more on that looking for that magical smoke, none smelt or seen; just keeps getting better.? At that point, just for fun once again, I attached an antenna to see if it can receive on the BC bands.? Low and behold I was able to tune in strong and some weak stations.? Next was 80M and I was able to tune in some of the more stronger stations, although the dials are off a little; wow looking really good.? So after an hour of playing around, I started creeping up to 110 Vac and let it sit for a little on that.? By the time I hit 120 Vac, only 5 Vac from the incoming line voltage to the house, that is when I could smell the magical smoke; Houston we have a problem.? So I let it sit for a while on that setting and let whatever it was that was baking, although I kept a close eye and hand on the transformer, finish cooking such that I could see the magical smoke or at least a crispy component.? So the culprit turned out to be R68, a 390 Ohm 1W resister in line with the Cathode/Suppressor Grid of the 6K6GT audio tube? A quick voltage check showed ~22.4 Vdc at that point, yet the schematic shows it should be 17 Vdc.? So a quick calculation indicated that the resistor was actually dissipating ~1.25W of power with the radio sitting on 120 Vac, a little over what it is rated for.? I replaced it with another 1W resistor for now and a new electrolytic cap as well. Now I only move the Vac momentarily from 100 Vac to 125 Vac to check the voltage in the various other areas to see what is really going on at todays higher Vac.? In retrospect I will probably replace that resistor with a 390 Ohm 3W pull I have in my junk box.? But I am debating on whether to change the value to get closer to 17 Vdc when running the radio with 125 Vac input.? I have seen a couple of designs showing a 500 Ohm used in the same situation when faced with the same Plate and Screening Grid voltages.? After a quick calculation 500 Ohms would drop it back to ~17 Vdc when running on our normal home Vac voltages.? Decisions decisions. ? Thank you, ? Mike W5CUL ? ? Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a variable inductor.?? It is capable of several turns either way from its ideal position.?? To index the control properly, there is a stop mechanism which is (again, as I recall) built into the knob.?? There is a combination of tang and milled slot that prevents rotation of the control more than 300 degrees or so.?? The "bump" you are experiencing is probably this stop mechanism and is due to the knob not being fully seated on the shaft, i.e. too far away from the front panel.?? If the "bump" is in the middle of the BFO range, then there is an alignment issue as well.?? Perform the BFO alignment as per the manual.?? Then install the knob centered and as close to the panel as it will go.?? You should now have a rotational limit at the extremes (+/- 5 on the knob skirt).??? Hopefully, the repetitive forcing of the knob past the stop has not worn the mechanism down to the point where it can no longer be made to function.
73,
--
Jim T.
KB6GM
|
Re: Calling all SX-100 Owners
Check the grid voltage, if it is too high (+) there will be too much current drawn across the plate and cathode resistors, usually caused by a bad coupling cap
toggle quoted message
Show quoted text
The resistor is for grid bias. Check the plate and screen voltages
?Actually, measure the resistor. Composition resistors rend to go up in value.? ?That would cause the drop across the resistor to go up.? It doesn't hurt to have more dissipation.? 17V ACROSS 390V is about 0.7 watts so a one watt is marginal.?
It will run hot which will make it drift more.? I bet it's way off value.? The larger resistor should be ok but 3 watts is an odd value,? usually next size is 2 watts and then five watts.? Check it's value before using it.? Also? , if there is a bypass capacitor
make sure it's ok.
? ?I think you are overdoing the VRiac business.? Of the filter caps don't short right away they are probably not going to.? I assume this variac is metered or you have some other means of watching for a sudden rise in line current.
-------- Original message --------
From: Mike <w5cul@...>
Date: 9/13/22 6:51 PM (GMT-08:00)
Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners
Thank you Jim and All!!!
?
Very good information from everyone.? This is certainly a haven of Hallicrafters Experts!!
?
Jim, I certainly hope that is the issue as opposed to a bent shaft as was another possibility mentioned by another gentleman.? I do not relish digging the assembly out of its make shift can to inspect the mechanics.? But if I must, then
I must.
?
In the meantime, just for fun, before any cap replacement, I put the receiver on a variac and slowly brought it up watching for any of that magical smoke to escape.? When I say slowly, I am talking about advancing the variac 10 Vac every
15 minutes or so.? This also helps in reforming some of those old caps along the way, although I will be replacing all of them soon.? By the time I hit roughly 40/50 Vac on the variac I could see dial lights starting to perk up; so far so good.? When I hit
around 70 Vac or a little more I was hearing good rushing noise coming out of the speaker; so far even better.? I stopped at around 100 Vac and let it soak more on that looking for that magical smoke, none smelt or seen; just keeps getting better.? At that
point, just for fun once again, I attached an antenna to see if it can receive on the BC bands.? Low and behold I was able to tune in strong and some weak stations.? Next was 80M and I was able to tune in some of the more stronger stations, although the dials
are off a little; wow looking really good.? So after an hour of playing around, I started creeping up to 110 Vac and let it sit for a little on that.? By the time I hit 120 Vac, only 5 Vac from the incoming line voltage to the house, that is when I could smell
the magical smoke; Houston we have a problem.? So I let it sit for a while on that setting and let whatever it was that was baking, although I kept a close eye and hand on the transformer, finish cooking such that I could see the magical smoke or at least
a crispy component.? So the culprit turned out to be R68, a 390 Ohm 1W resister in line with the Cathode/Suppressor Grid of the 6K6GT audio tube.? A quick voltage check showed ~22.4 Vdc at that point, yet the schematic shows it should be 17 Vdc.? So a quick
calculation indicated that the resistor was actually dissipating ~1.25W of power with the radio sitting on 120 Vac, a little over what it is rated for.? I replaced it with another 1W resistor for now and a new electrolytic cap as well. Now I only move the
Vac momentarily from 100 Vac to 125 Vac to check the voltage in the various other areas to see what is really going on at todays higher Vac.? In retrospect I will probably replace that resistor with a 390 Ohm 3W pull I have in my junk box.? But I am debating
on whether to change the value to get closer to 17 Vdc when running the radio with 125 Vac input.? I have seen a couple of designs showing a 500 Ohm used in the same situation when faced with the same Plate and Screening Grid voltages.? After a quick calculation
500 Ohms would drop it back to ~17 Vdc when running on our normal home Vac voltages.? Decisions decisions.
?
Thank you,
?
Mike
W5CUL
?
?
Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a variable inductor.?? It is capable of several turns either way from its ideal position.?? To index the control properly, there is a stop mechanism which is (again, as I recall) built into the knob.??
There is a combination of tang and milled slot that prevents rotation of the control more than 300 degrees or so.?? The "bump" you are experiencing is probably this stop mechanism and is due to the knob not being fully seated on the shaft, i.e. too far away
from the front panel.?? If the "bump" is in the middle of the BFO range, then there is an alignment issue as well.?? Perform the BFO alignment as per the manual.?? Then install the knob centered and as close to the panel as it will go.?? You should now have
a rotational limit at the extremes (+/- 5 on the knob skirt).??? Hopefully, the repetitive forcing of the knob past the stop has not worn the mechanism down to the point where it can no longer be made to function.
73,
--
Jim T.
KB6GM
|
Re: Calling all SX-100 Owners
The resistor is for grid bias. Check the plate and screen voltages ?Actually, measure the resistor. Composition resistors rend to go up in value.? ?That would cause the drop across the resistor to go up.? It doesn't hurt to have more dissipation.? 17V ACROSS 390V is about 0.7 watts so a one watt is marginal.? It will run hot which will make it drift more.? I bet it's way off value.? The larger resistor should be ok but 3 watts is an odd value,? usually next size is 2 watts and then five watts.? Check it's value before using it.? Also? , if there is a bypass capacitor make sure it's ok. ? ?I think you are overdoing the VRiac business.? Of the filter caps don't short right away they are probably not going to.? I assume this variac is metered or you have some other means of watching for a sudden rise in line current.
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-------- Original message -------- From: Mike <w5cul@...> Date: 9/13/22 6:51 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners
Thank you Jim and All!!! ? Very good information from everyone.? This is certainly a haven of Hallicrafters Experts!! ? Jim, I certainly hope that is the issue as opposed to a bent shaft as was another possibility mentioned by another gentleman.? I do not relish digging the assembly out of its make shift can to inspect the mechanics.? But if I must, then I must. ? In the meantime, just for fun, before any cap replacement, I put the receiver on a variac and slowly brought it up watching for any of that magical smoke to escape.? When I say slowly, I am talking about advancing the variac 10 Vac every 15 minutes or so.? This also helps in reforming some of those old caps along the way, although I will be replacing all of them soon.? By the time I hit roughly 40/50 Vac on the variac I could see dial lights starting to perk up; so far so good.? When I hit around 70 Vac or a little more I was hearing good rushing noise coming out of the speaker; so far even better.? I stopped at around 100 Vac and let it soak more on that looking for that magical smoke, none smelt or seen; just keeps getting better.? At that point, just for fun once again, I attached an antenna to see if it can receive on the BC bands.? Low and behold I was able to tune in strong and some weak stations.? Next was 80M and I was able to tune in some of the more stronger stations, although the dials are off a little; wow looking really good.? So after an hour of playing around, I started creeping up to 110 Vac and let it sit for a little on that.? By the time I hit 120 Vac, only 5 Vac from the incoming line voltage to the house, that is when I could smell the magical smoke; Houston we have a problem.? So I let it sit for a while on that setting and let whatever it was that was baking, although I kept a close eye and hand on the transformer, finish cooking such that I could see the magical smoke or at least a crispy component.? So the culprit turned out to be R68, a 390 Ohm 1W resister in line with the Cathode/Suppressor Grid of the 6K6GT audio tube.? A quick voltage check showed ~22.4 Vdc at that point, yet the schematic shows it should be 17 Vdc.? So a quick calculation indicated that the resistor was actually dissipating ~1.25W of power with the radio sitting on 120 Vac, a little over what it is rated for.? I replaced it with another 1W resistor for now and a new electrolytic cap as well. Now I only move the Vac momentarily from 100 Vac to 125 Vac to check the voltage in the various other areas to see what is really going on at todays higher Vac.? In retrospect I will probably replace that resistor with a 390 Ohm 3W pull I have in my junk box.? But I am debating on whether to change the value to get closer to 17 Vdc when running the radio with 125 Vac input.? I have seen a couple of designs showing a 500 Ohm used in the same situation when faced with the same Plate and Screening Grid voltages.? After a quick calculation 500 Ohms would drop it back to ~17 Vdc when running on our normal home Vac voltages.? Decisions decisions. ? Thank you, ? Mike W5CUL ? ? Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a variable inductor.?? It is capable of several turns either way from its ideal position.?? To index the control properly, there is a stop mechanism which is (again, as I recall) built into the knob.?? There is a combination of tang and milled slot that prevents rotation of the control more than 300 degrees or so.?? The "bump" you are experiencing is probably this stop mechanism and is due to the knob not being fully seated on the shaft, i.e. too far away from the front panel.?? If the "bump" is in the middle of the BFO range, then there is an alignment issue as well.?? Perform the BFO alignment as per the manual.?? Then install the knob centered and as close to the panel as it will go.?? You should now have a rotational limit at the extremes (+/- 5 on the knob skirt).??? Hopefully, the repetitive forcing of the knob past the stop has not worn the mechanism down to the point where it can no longer be made to function.
73,
--
Jim T.
KB6GM
|
Re: Calling all SX-100 Owners
Thank you Jim and All!!! ? Very good information from everyone.? This is certainly a haven of Hallicrafters Experts!! ? Jim, I certainly hope that is the issue as opposed to a bent shaft as was another possibility mentioned by another gentleman.? I do not relish digging the assembly out of its make shift can to inspect the mechanics.? But if I must, then I must. ? In the meantime, just for fun, before any cap replacement, I put the receiver on a variac and slowly brought it up watching for any of that magical smoke to escape.? When I say slowly, I am talking about advancing the variac 10 Vac every 15 minutes or so.? This also helps in reforming some of those old caps along the way, although I will be replacing all of them soon.? By the time I hit roughly 40/50 Vac on the variac I could see dial lights starting to perk up; so far so good.? When I hit around 70 Vac or a little more I was hearing good rushing noise coming out of the speaker; so far even better.? I stopped at around 100 Vac and let it soak more on that looking for that magical smoke, none smelt or seen; just keeps getting better.? At that point, just for fun once again, I attached an antenna to see if it can receive on the BC bands.? Low and behold I was able to tune in strong and some weak stations.? Next was 80M and I was able to tune in some of the more stronger stations, although the dials are off a little; wow looking really good.? So after an hour of playing around, I started creeping up to 110 Vac and let it sit for a little on that.? By the time I hit 120 Vac, only 5 Vac from the incoming line voltage to the house, that is when I could smell the magical smoke; Houston we have a problem.? So I let it sit for a while on that setting and let whatever it was that was baking, although I kept a close eye and hand on the transformer, finish cooking such that I could see the magical smoke or at least a crispy component.? So the culprit turned out to be R68, a 390 Ohm 1W resister in line with the Cathode/Suppressor Grid of the 6K6GT audio tube.? A quick voltage check showed ~22.4 Vdc at that point, yet the schematic shows it should be 17 Vdc.? So a quick calculation indicated that the resistor was actually dissipating ~1.25W of power with the radio sitting on 120 Vac, a little over what it is rated for.? I replaced it with another 1W resistor for now and a new electrolytic cap as well. Now I only move the Vac momentarily from 100 Vac to 125 Vac to check the voltage in the various other areas to see what is really going on at todays higher Vac.? In retrospect I will probably replace that resistor with a 390 Ohm 3W pull I have in my junk box.? But I am debating on whether to change the value to get closer to 17 Vdc when running the radio with 125 Vac input.? I have seen a couple of designs showing a 500 Ohm used in the same situation when faced with the same Plate and Screening Grid voltages.? After a quick calculation 500 Ohms would drop it back to ~17 Vdc when running on our normal home Vac voltages.? Decisions decisions. ? Thank you, ? Mike W5CUL ?
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From: [email protected] < [email protected]> On Behalf Of JThorusen Sent: Tuesday, September 13, 2022 7:15 PM To: [email protected]Subject: Re: [HallicraftersRadios] Calling all SX-100 Owners ? Greetings to Mike and the Group:
?? As I recall, the SX-100 BFO pitch control is indeed a variable inductor.?? It is capable of several turns either way from its ideal position.?? To index the control properly, there is a stop mechanism which is (again, as I recall) built into the knob.?? There is a combination of tang and milled slot that prevents rotation of the control more than 300 degrees or so.?? The "bump" you are experiencing is probably this stop mechanism and is due to the knob not being fully seated on the shaft, i.e. too far away from the front panel.?? If the "bump" is in the middle of the BFO range, then there is an alignment issue as well.?? Perform the BFO alignment as per the manual.?? Then install the knob centered and as close to the panel as it will go.?? You should now have a rotational limit at the extremes (+/- 5 on the knob skirt).??? Hopefully, the repetitive forcing of the knob past the stop has not worn the mechanism down to the point where it can no longer be made to function.
73,
--
Jim T.
KB6GM
|
RJ Mattson
Bill (Group Owner)
k7wxk
waltcates
Trent N4DTF EM55
Bruce Collins