I've never worked on a 2C, but did I read that the shaft (or bushing?) is made of a fibrous material? If so, will that absorb oil and expand?
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Dave Edwards" <kd2e@...>
To: "DRAKE-RADIO" <[email protected]>
Cc: "Gary Follett" <xntrick1948@...>
Sent: Wednesday, March 22, 2023 6:51:25 AM
Subject: Re: [DRAKE-RADIO] 2-C Receiver I would first check really carefully...with a loupe or magnifying glass,
and a STRONG light to see if the existing knob is not already split perhaps.
As far as the control itself...I would avoid spray stuff.
I'd suggest a thin oil, with a toothpick. study the control carefully,
finding the bearing points. Drop one drop of oil wherever you see the
point where something supports the rotation (perhaps front and rear
bearing??)
Again, a strong lamp is key. Be nice to the 2C. It is an amazing, and
trailblazing rig!!
...Dave? KD2E
On 3/21/23 5:17 PM, Dave via groups.io wrote:
Gary, Dave, John,
Thanks for the replies!
I removed the knob this afternoon and it is in good shape.
It looks like the set screw presses against a fiber like bushing that
surrounds the shaft and this presses against the shaft for a tight fit.
It did not feel stuck but I cannot turn it by just grabbing the shaft
with my fingers.
The shaft is round without a flat spot so I guess it is just a tight
compression fit that does the work.
I can move the switch to all three positions with a pair of pliers and
LSB/USB works just fine !!!
I may open it up and look at the underside and then try some lubricant
of some sort on the shaft, any suggestions?
I have WD40 & PB Blaster here to loosen it up some to start but maybe
some kind of light oil after that?
Dave KC3AM
On 3/20/2023 9:50 PM, Gary Follett wrote:
That knob? should most certainly operate with a click at each
position, allowing reception of AM, USB and LSB/CW.
There are two possibilities. One is simple, that the set screw for
the knob is loose. I think this is a setscrew type knob¡
If the set screw is very tight but you still cannot get a switch
action, remove the knob and have a look at the shaft. Try to turn it
gently with a pliers. If you get the same result, remove the cover
and have a look at the coupling between the small inner shaft and the
switch behind it to see if it is loose or broken. That coupling is
below the chassis (underside) towards the back, with the shaft going
between the coils of the bandpass filter coils.
Try that. If no joy, I have the last possibility you. Don¡¯t want to
hear unless you are really good at repair work.
Gary
W0DVN
On Mar 20, 2023, at 8:28 PM, Dave via groups.io
<kc3am@...> wrote:
Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around
and has no effect.
This is the first time I have tried to listen to SSB so this is new
to me.
Looking at the schematic before I open it up it looks like the mode
switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Re: R4C 1500hz crystal filter damaged
Rob,
I can see the problem with the glass seal failing. ?It¡¯s pretty clear looking carefully at the pin. ?My other three filters are Network Science and I think they will simply never be taken out. ??
I¡¯m trying the JB weld solution and will post the result. ?If it fails I¡¯ll be looking for a new used one, or one from that company that currently sells drake filters.?
heck, it¡¯s only about 48 year old.
thanks Rob and all.
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
Why not get some volunteers to start it up on 20? ?All we need are a few people willing to take turns being NCS. The harder part will be to find the right time and frequency, since there are likely other regular nets around, and to not schedule it at the same time as other interest group nets that are similar. It would take some coordination and the net itself would likely start slowly.?
For precedent, there are Collins and Kenwood nets on 20, I believe. I am of the opinion that there are many more people interested in Drakes than what existed even a few years ago.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
Sent from Proton Mail for iOS
On Tue, Mar 21, 2023 at 4:15 PM, Mark - WB0IQK < mgilger@...> wrote: We tried a 20 meter net many years ago and it never worked out. Very limited check-ins.? We also had a 75m swap net and had to disband that some years ago due to lack of participation.?
73's,
Mark, WB0IQK?
|
I would first check really carefully...with a loupe or magnifying glass, and a STRONG light to see if the existing knob is not already split perhaps.
As far as the control itself...I would avoid spray stuff.
I'd suggest a thin oil, with a toothpick. study the control carefully, finding the bearing points. Drop one drop of oil wherever you see the point where something supports the rotation (perhaps front and rear bearing??)
Again, a strong lamp is key. Be nice to the 2C. It is an amazing, and trailblazing rig!!
...Dave? KD2E
toggle quoted message
Show quoted text
On 3/21/23 5:17 PM, Dave via groups.io wrote: Gary, Dave, John,
Thanks for the replies!
I removed the knob this afternoon and it is in good shape.
It looks like the set screw presses against a fiber like bushing that surrounds the shaft and this presses against the shaft for a tight fit.
It did not feel stuck but I cannot turn it by just grabbing the shaft with my fingers.
The shaft is round without a flat spot so I guess it is just a tight compression fit that does the work.
I can move the switch to all three positions with a pair of pliers and LSB/USB works just fine !!!
I may open it up and look at the underside and then try some lubricant of some sort on the shaft, any suggestions?
I have WD40 & PB Blaster here to loosen it up some to start but maybe some kind of light oil after that?
Dave KC3AM
On 3/20/2023 9:50 PM, Gary Follett wrote:
That knob? should most certainly operate with a click at each position, allowing reception of AM, USB and LSB/CW.
There are two possibilities. One is simple, that the set screw for the knob is loose. I think this is a setscrew type knob¡
If the set screw is very tight but you still cannot get a switch action, remove the knob and have a look at the shaft. Try to turn it gently with a pliers. If you get the same result, remove the cover and have a look at the coupling between the small inner shaft and the switch behind it to see if it is loose or broken. That coupling is below the chassis (underside) towards the back, with the shaft going between the coils of the bandpass filter coils.
Try that. If no joy, I have the last possibility you. Don¡¯t want to hear unless you are really good at repair work.
Gary
W0DVN
On Mar 20, 2023, at 8:28 PM, Dave via groups.io <kc3am@...> wrote:
Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around and has no effect.
This is the first time I have tried to listen to SSB so this is new to me.
Looking at the schematic before I open it up it looks like the mode switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Re: R4C power supply question
Rob,
Yes I completely rebuilt the supply adding a 7812 regulator board which are dirt cheap on Amazon and elsewhere. I also added an LM380 audio board. again, dirt cheap, and everything runs from regulated 12V. I use 3 diodes in series to lower the low voltage to the 7812 to about 14.5-15 volts and the 7812 loafs along.
My R4C never had the C201 as far as I remember although I ripped quite a bit off the power supply board. There is no heat there anymore. I do have some very low level hum that is coming from somewhere ahead of the volume pot. It is absolutely clean with the pot disconnected. It is very low level, but being a purist, I was looking for possible fixes.
I wonder if others have measured filament voltage. I used several digital meters and they all agreed that the filaments were running at about 7.0-7.1 volts. This is with a 121 volt line. I figured I needed about .3 ohms to lower it so I wound about 6 feet of #30 enameled wire on a high value 2W resistor which dropped it about .5 volts or so.
I was also wondering when the LM380 first came out. The earliest data I can find is an app note dated 1972, so it had to be early in the R4C production, My R4C is SN 28387 which is very close to the end of production in 1976 or later so it certainly could have had a much better power supply and audio amp at that late date.? Think of the space that would have been saved as most of the powers supply and audio boards would have gone away, I guess by 1976 they were working on the TR7 design which used the newer chips.
Doug, WA3DSP
|
Re: R4C 1500hz crystal filter damaged
Lionel,
?
Unfortunately the glass to metal pin breakage was a problem with Network Sciences pins.? The best hermetic pins were filters made by Piezo Technology.
?
Rob, NC0B
?
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From: [email protected] [mailto:[email protected]]
On Behalf Of Lionel B
Sent: Tuesday, March 21, 2023 9:43 AM
To: [email protected]
Subject: Re: [DRAKE-RADIO] R4C 1500hz crystal filter damaged
?
Hi Rob,
It is Network Sciences
Date Code (?) 7905
Thanks Lionel?
|
Re: R4C power supply question
Doug,
?
Yes it had to do with reducing audio hum.? The whole power supply was poorly designed from day one with too much ripple in the 150 volt, -70 volt and 14 volt
supplies.? In this case I think it reduced 120 Hz hum and made 60 Hz hum worse which wasn¡¯t reproduced as well by the speaker.?
?
I must have sold 500 or more total replacement power supply boards that got rid of the ripple (hum) and eliminated the two 5-watt dropping resistors.?? Once
the 12-volt three-terminal regulator came along, I never understood why Drake never redesigned the power supply.? Eliminating the heat from those two dropping resistors, plus replacing the power? hog audio amplifier, made the PTO more stable. ?The replacement
boards were the RPS-4 and AMP-4.
?
Rob, NC0B
?
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From: [email protected] [mailto:[email protected]]
On Behalf Of Doug Crompton WA3DSP
Sent: Tuesday, March 21, 2023 12:02 PM
To: [email protected]
Subject: [DRAKE-RADIO] R4C power supply question
?
In comparing early and later R4C power supply schematics, a capacitor (C201) was added going from the output of the low voltage diodes to the high end of the filament string. It is listed as 20uf 150V. I am attaching a schematic showing
it. I was wondering what its purpose was and why it was added. Does anyone have any ideas? I thought it might have something to do with audio hum.?
?
Doug, WA3DSP
|
For a temporary fix, what you suggest is OK. Others have had success with WD-40 in this application.
If it were MY receiver, I would remove the switch, disassemble the bushing/shaft assembly, thoroughly clean the old grease out and polish both the shaft and bushing with microfine polishing compound. I use lithium grease for reassembly, just a tiny bit.
The trick to disassembling the shaft/bushing assembly is prying the wire ring in front of the bushing, as this holds the shaft into the bushing. It is not spring steel so you can bend it to get it off and then clamp it back into place when you are done. ?Be sure to not lose the little ball bearing that acts to locate the switch at its positions.
Gary
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On Mar 21, 2023, at 4:17 PM, Dave via groups.io <kc3am@...> wrote:
Gary, Dave, John,Thanks for the replies!I removed the knob this afternoon and it is in good shape.It looks like the set screw presses against a fiber like bushing that surrounds the shaft and this presses against the shaft for a tight fit.It did not feel stuck but I cannot turn it by just grabbing the shaft with my fingers.The shaft is round without a flat spot so I guess it is just a tight compression fit that does the work.I can move the switch to all three positions with a pair of pliers and LSB/USB works just fine !!!I may open it up and look at the underside and then try some lubricant of some sort on the shaft, any suggestions?I have WD40 & PB Blaster here to loosen it up some to start but maybe some kind of light oil after that?Dave KC3AMOn 3/20/2023 9:50 PM, Gary Follett wrote:That knob ?should most certainly operate with a click at each position, allowing reception of AM, USB and LSB/CW.
There are two possibilities. One is simple, that the set screw for the knob is loose. I think this is a setscrew type knob¡
If the set screw is very tight but you still cannot get a switch action, remove the knob and have a look at the shaft. Try to turn it gently with a pliers. If you get the same result, remove the cover and have a look at the coupling between the small inner shaft and the switch behind it to see if it is loose or broken. That coupling is below the chassis (underside) towards the back, with the shaft going between the coils of the bandpass filter coils.
Try that. If no joy, I have the last possibility you. Don¡¯t want to hear unless you are really good at repair work.
Gary
W0DVN
On Mar 20, 2023, at 8:28 PM, Dave via groups.io <kc3am@...> wrote:
Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around and has no effect.
This is the first time I have tried to listen to SSB so this is new to me.
Looking at the schematic before I open it up it looks like the mode switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
I remember the Drake swap net on 75 meters.?
I was a new ham in the late 80s and always wanted a Drake C line. WZ8O, now W8NS, Don, put out his phone number and said he had one for sale.
I called him up and talked with him for awhile and told him that I wanted it. Two or Three days later, the radio arrived. I'm sure my check had never even reached his house yet.?
I called him up of course, thrilled, and thanking him profusely for getting the radio to me so quickly, and of course trusting me to make it all right.??
What a great history the Drake guys have and have always helped me out a lot. Thanks again for all the education you have passed along to me, as well as good faith.?
73
Mark
W0NCL
-----Original Message-----
From: Mark - WB0IQK <mgilger@...>
To: [email protected]
Sent: Tue, Mar 21, 2023 3:15 pm
Subject: Re: [DRAKE-RADIO] DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
We tried a 20 meter net many years ago and it never worked out. Very limited check-ins.? We also had a 75m swap net and had to disband that some years ago due to lack of participation.?
73's,
Mark, WB0IQK?
|
Gary, Dave, John,
Thanks for the replies!
I removed the knob this afternoon and it is in good shape.
It looks like the set screw presses against a fiber like bushing that surrounds the shaft and this presses against the shaft for a tight fit.
It did not feel stuck but I cannot turn it by just grabbing the shaft with my fingers.
The shaft is round without a flat spot so I guess it is just a tight compression fit that does the work.
I can move the switch to all three positions with a pair of pliers and LSB/USB works just fine !!!
I may open it up and look at the underside and then try some lubricant of some sort on the shaft, any suggestions?
I have WD40 & PB Blaster here to loosen it up some to start but maybe some kind of light oil after that?
Dave KC3AM
toggle quoted message
Show quoted text
On 3/20/2023 9:50 PM, Gary Follett wrote: That knob should most certainly operate with a click at each position, allowing reception of AM, USB and LSB/CW.
There are two possibilities. One is simple, that the set screw for the knob is loose. I think this is a setscrew type knob¡
If the set screw is very tight but you still cannot get a switch action, remove the knob and have a look at the shaft. Try to turn it gently with a pliers. If you get the same result, remove the cover and have a look at the coupling between the small inner shaft and the switch behind it to see if it is loose or broken. That coupling is below the chassis (underside) towards the back, with the shaft going between the coils of the bandpass filter coils.
Try that. If no joy, I have the last possibility you. Don¡¯t want to hear unless you are really good at repair work.
Gary
W0DVN
On Mar 20, 2023, at 8:28 PM, Dave via groups.io <kc3am@...> wrote:
Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around and has no effect.
This is the first time I have tried to listen to SSB so this is new to me.
Looking at the schematic before I open it up it looks like the mode switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
No problem - it was just a suggestion since I would like to be able to check in with my Twins.
I will keep looking for better band conditions in the rising sunspot cycle.
- Steve? W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome" - Adaptation of the U.S. Marine Corps motto
"There are no rules here!...We're trying to accomplish something!!"
- Thomas Edison
"Success is not final, failure is not fatal.? It is the courage to continue that counts." -?Winston Churchill
On Tuesday, March 21, 2023 at 02:15:29 PM MDT, Mark - WB0IQK <mgilger@...> wrote:
We tried a 20 meter net many years ago and it never worked out. Very limited check-ins.? We also had a 75m swap net and had to disband that some years ago due to lack of participation.?
73's,
Mark, WB0IQK?
|
Re: DRAKE TECHNICAL NET UPDATE ( March 19, 2023 )
We tried a 20 meter net many years ago and it never worked out. Very limited check-ins.? We also had a 75m swap net and had to disband that some years ago due to lack of participation.?
73's,
Mark, WB0IQK?
|
Re: Rob, Question re your "Custom Front Panel Switch" mod
The performance of ceramic caps depends on the exact type of material.? npo type are very good ,? it is the "hi k" type that have problems.? Temperature compensating caps have charities similar to NPO.? The best performance overall is polypropylene.? Look up polypropylene and mylar to see the differences.? Old tubular caps are not all paper but most are. Plastic film caps are in all ways superior.
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-------- Original message -------- From: Gary Follett <xntrick1948@...> Date: 3/21/23 10:21 AM (GMT-08:00) Subject: Re: [DRAKE-RADIO] Rob, Question re your "Custom Front Panel Switch" mod
Ceramic capacitors are bottom rung devices, with differing temperature coefficients depending on type (NPO being the best for routine cooling and bypassing applications). They do not fare well at low frequencies and they can be quite noisy, even somewhat microphonic.They are generally not used in signal path applications.
The tubular ones to which you refer are, at this radio¡¯s vintage, paper capacitors. They are non-polarized except for the fact that the outermost metallization is typically tied to ground to reduce noise pickup and to ensure that the outermost layer is at ground potential. That is why these types often (not always) have a band on one end to indicate which end should be grounded.
To replace these capacitors, the best choice would be modern Mylar capacitors, readily available for DigiKey or Mouser. I always buy 630 volt devices so I only need to stock one drawer of each value. There is no downside to using higher than needed voltage rated parts, other than size. However, the modern parts are so much smaller than the originals that this is not an issue.
The biggest issue with modern parts is that the leads are often not long enough to reach the tie points in older radios (particularly in Collins radios). That won¡¯t be a problem generally with Drake radios though.
Gary
W0DVN On Mar 21, 2023, at 11:37 AM, Bill Leonard N0CU <billincolo73@...> wrote:
I don't see any mention as to what type of capacitors to use. The reason I ask is I don't know why Drake used large tubular capacitors in their design. Is there any reason ceramic capacitors can't be used?
--
Bill N0CU
|
R4C power supply question
In comparing early and later R4C power supply schematics, a capacitor (C201) was added going from the output of the low voltage diodes to the high end of the filament string. It is listed as 20uf 150V. I am attaching a schematic showing it. I was wondering what its purpose was and why it was added. Does anyone have any ideas? I thought it might have something to do with audio hum.?
?
Doug, WA3DSP
|
Re: Rob, Question re your "Custom Front Panel Switch" mod
Ceramic capacitors are bottom rung devices, with differing temperature coefficients depending on type (NPO being the best for routine cooling and bypassing applications). They do not fare well at low frequencies and they can be quite noisy, even somewhat microphonic.They are generally not used in signal path applications.
The tubular ones to which you refer are, at this radio¡¯s vintage, paper capacitors. They are non-polarized except for the fact that the outermost metallization is typically tied to ground to reduce noise pickup and to ensure that the outermost layer is at ground potential. That is why these types often (not always) have a band on one end to indicate which end should be grounded.
To replace these capacitors, the best choice would be modern Mylar capacitors, readily available for DigiKey or Mouser. I always buy 630 volt devices so I only need to stock one drawer of each value. There is no downside to using higher than needed voltage rated parts, other than size. However, the modern parts are so much smaller than the originals that this is not an issue.
The biggest issue with modern parts is that the leads are often not long enough to reach the tie points in older radios (particularly in Collins radios). That won¡¯t be a problem generally with Drake radios though.
Gary
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On Mar 21, 2023, at 11:37 AM, Bill Leonard N0CU <billincolo73@...> wrote:
I don't see any mention as to what type of capacitors to use. The reason I ask is I don't know why Drake used large tubular capacitors in their design. Is there any reason ceramic capacitors can't be used?
--
Bill N0CU
|
Re: Rob, Question re your "Custom Front Panel Switch" mod
Hi Bill,
I use Mylar capacitors. ?Leakage and Q, but I suppose you could try ceramic.?
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Show quoted text
On Mar 21, 2023, at 10:37 AM, Bill Leonard N0CU <billincolo73@...> wrote:
?I don't see any mention as to what type of capacitors to use. The reason I ask is I don't know why Drake used large tubular capacitors in their design. Is there any reason ceramic capacitors can't be used?
--
Bill N0CU
|
Rob, Question re your "Custom Front Panel Switch" mod
I don't see any mention as to what type of capacitors to use. The reason I ask is I don't know why Drake used large tubular capacitors in their design. Is there any reason ceramic capacitors can't be used?
--
Bill N0CU
|
Re: R4C 1500hz crystal filter damaged
Hi Rob,
It is Network Sciences
Date Code (?) 7905
Thanks Lionel?
|
One caution!
If the knob is loose, please do NOT overtighten the set screw. This will surely result in the knob being stripped or split.?
If it's loose because the shaft is hard to turn, remove the knob and fix the problem preventing the rotation (usually some thin oil in the shaft/bushing of the control) , then reattach the knob.
You got this!
John K5MO
On Tue, Mar 21, 2023 at 8:34?AM Dave Edwards < kd2e@...> wrote: A normal selector switch.
Is your knob set screw loose?
....Dave
On 3/20/23 9:28 PM, Dave via wrote:
> Hello everyone,
>
> Last summer I picked up a 2-C to go with my 2-NT.
> I have been using it for CW without any troubles.
> I tried to listen to some SSB signals tonight and I found a problem...
>
> I cannot tune in the SSB signals, the mode control just spins around
> and has no effect.
>
> This is the first time I have tried to listen to SSB so this is new to
> me.
>
> Looking at the schematic before I open it up it looks like the mode
> switch should have a few positions to it and not just spin around.
>
> Am I correct?
>
> Thanks much,
>
> Dave KC3AM
>
>
>
>
>
>
|
A normal selector switch.
Is your knob set screw loose?
....Dave
toggle quoted message
Show quoted text
On 3/20/23 9:28 PM, Dave via groups.io wrote: Hello everyone,
Last summer I picked up a 2-C to go with my 2-NT.
I have been using it for CW without any troubles.
I tried to listen to some SSB signals tonight and I found a problem...
I cannot tune in the SSB signals, the mode control just spins around and has no effect.
This is the first time I have tried to listen to SSB so this is new to me.
Looking at the schematic before I open it up it looks like the mode switch should have a few positions to it and not just spin around.
Am I correct?
Thanks much,
Dave KC3AM
|
Doug Crompton WA3DSP
Rob Sherwood
