Re: [Drakelist] R-4A PTO: It wasn't the transistors (entirely)

[Curt Nixon]

Hi Jim:

I didn't know Tri-Flo came as a grease also..nice.  I do use a white 
teflon grease in the bike and radios but different brand.  I have some 
stuff called WGL that I cme across on the boat.  totally waterproof and 
is nearly a pure teflon in grease form.  never dries up because it has 
no hydrocarbon-based solvents or oils.  I use it for leadscrews, the 
compensating sliders in the 390 PTO, etc.  One small can has lasted me 
20 years.


Curt
KU8L



On 7/29/2011 10:54 PM, Jim Shorney wrote:

On Fri, 29 Jul 2011 10:59:53 -0400, Curt Nixon wrote:


1.  Tri-Flow is indeed a teflon-based spray lubricant.  has a distinct odor of amyl acetate as 
well..."banana oil"  It is a very nice lubricant for "dry" type applications.  
It might be appropriate on the yoke slider for instance on the PTO.  Not for gears or items 
requiring oil.  Good for sliding-type applications.  Not messy.

Tri-Flow is also a PTFE-based bicycle grease. I use it all the time anywhere
that grease is called for in a radio. It's great stuff.

73

-Jim


--
Ham Radio NU0C
Lincoln, Nebraska, U.S.S.A.
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, 
HyGain 3750, IBM PS/2 - all vintage, all the time!

"Give a man a URL, and he will learn for an hour; teach him to Google, and he will 
learn for a lifetime."

HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
http://incolor.inetnebr.com/jshorney
http://www.nebraskaghosts.org



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Re: [Drakelist] R-4A PTO: It wasn't the transistors (entirely)

[Jim Shorney]

Hi Curt,

On Sat, 30 Jul 2011 10:12:39 -0400, Curt Nixon wrote:

>I didn't know Tri-Flo came as a grease also..nice.  I do use a white 
>teflon grease in the bike and radios but different brand.

This is a clear grease - they say it can be found in the better bike shops, but
I had to get my (now near-empty) 3 Oz. tube via eBay.  I've ended up using this
stuff just about EVERYWHERE, I just love it. I was led to it after I misplaced
my highly prized and guarded tube of RadShack Teflon grease that I had for
years (actually, my second tube), and found that RadShack no longer carries the
stuff... :(  Althought they do have a small oiler containing Teflon based oil,
which is very similar to one that I found at Ace Hardware a couple of years
ago. The Tri-Flow grease is more viscuous than other similar greases, and seems
to stay put pretty well. I got a little over-enthusiastic with it and used a
bit too much in my TR-7 dial drive, and ended up with a fairly stiff tuning
knob - which is not a bad thing for fine frequency adjustments, but not so
great for band-surfing. I haven't re-done it yet, because I have two other
knobs that I can spin (RV-7 and R-7A). I did the RV-7 with a little less
grease, and it's silky. The R-7A was still factory-fresh (with greased Nylon),
so I haven't touched it.

I also have a tube of the Phil Woods Waterproof Bicycle Grease that the 390A
crowd likes so much, but I don't use it nearly as much. I don't know what it's
made of, but I used it in my Hy-Gain 3750 VFO gear train and it seems to work
well there. It's not as thick as Tri-Flow, so it's probably better for Jackson
drives and such.

73

-Jim


--
Ham Radio NU0C
Lincoln, Nebraska, U.S.S.A.
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, 
HyGain 3750, IBM PS/2 - all vintage, all the time!

"Give a man a URL, and he will learn for an hour; teach him to Google, and he 
will learn for a lifetime."

HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/
http://incolor.inetnebr.com/jshorney
http://www.nebraskaghosts.org



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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

I know from my experience in the semiconductor business that zeners
(especially those from a prior era) are notoriously noisy and can become
outright unstable to varying degrees.  You will not see this with a DVM or
other averaging type instrument.  You should put a scope on the zener and
turn up the gain as high as the scope will go while setting the time base
for anywhere from 1 to 100ms/div.  Make sure your scope ground connection is
right at the zener to keep stray pickup at a minimum.  If it is unstable you
will see the voltage jumping around in discrete steps.  A typical zener will
just exhibit "white" noise which looks like tall grass on the CRT.  Both the
discrete steps and the white noise will modulate the PTO.  The steps
manifest as annoying random freq shifts while the white noise just adds
to the noise sidebands of the oscillator.  The discrete jumps in zener
voltage are understood in the physics but unless folks are truly interested
in that stuff I won't go into it here.

Not to scold the Drake design team (whom I respect) and maybe mostly because
I witnessed how the sausage is actually made, but I would NEVER design a
zener into a circuit as noise sensitive as an oscillator, mixer or preamp.
I designed and built a homebrew antenna noise bridge.  Guess what I used as
the broadband noise source?

Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge  wrote:

> Well, it has been a long, strange trip here.
>
> Just finished a little experiment with the PTO and my K3.  First of all,
> the K3 is deaf as a post at 4.9 MHz ;-) but I did get enough of a signal
> through a scope probe hooked to the PTO output to confirm that it's the PTO
> that is shifting frequency.
>
> Having confirmed that, my next step will be replacing the 3000 pF and the
> zener - even though I'm fairly convinced the zener is okay (alright - I'll
> replace the 3000 pF first...).
>
> I have a sneaking suspicion that this may be one of the S.A.T. caps.  If
> so, it's going to be interesting since I no longer have a capacitance meter.
>
> Steve Wedge, W1ES/4
>
> "I can't complain, but sometimes I still do."
> - Joe Walsh
>
> If the above message appears, it came from Steve's Son of Laptop!
> - Original Message - From: "Garey Barrell" 
> To: "Steve Wedge" 
> Cc: 
> Sent: Friday, July 29, 2011 3:21 PM
> Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
>
>
> Steve -
>>
>> Yes, the PreMixer signal (V8) (BAND minus PTO) is the one that is piped
>> back and forth between the two units.
>>
>> All you have to do is listen to the PTO signal itself on a separate
>> receiver.  "0" on the dial = 5.455 MHz, "500" = 4.955.  The BFO crystal is
>> 5.595 MHz.  The BFO is a tube, V3, which I believe we swapped way back
>> towards the beginning of this odyssey!!  I also thought you had put a
>> counter on the PTO, but I guess that's another 'project'.  :-)   I typically
>> have three or four of these eMail projects going at one time, which is why I
>> like to keep the entire thread together.  Makes it easier to go back
>> occasionally just to review just what path got us 'here'!  :-)
>>
>> 73, Garey - K4OAH
>> Glen Allen, VA
>>
>> Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
>> and TR-4/C Service Supplement CDs
>> 
>>
>>
>> Steve Wedge wrote:
>>
>>> You know, Garey, I've been thinking about the xtal oscillator.  It would
>>> have to be part that doesn't get bandswitched - which would include THAT
>>> transistor.
>>>
>>> When the T-4X controls the frequency, it sounds great and never jumps
>>> frequency.  In looking at the schematic, I have been aware that the two
>>> solid-state oscillators (PTO and LO for the band) get mixed in V8 (IIRC) and
>>> that this combination gets overridden by the output of the T-4X's premixer.
>>>
>>> Looks like I am going to need a counter to find out.  I am loathe to dig
>>> into the T-4X because it's working so well and the PTO is much more
>>> difficult to remove from it due to the volume of wires in the area.
>>>
>>> 73,
>>>
>>> Steve, W1ES
>>>
>>>
>>> Date: Fri, 29 Jul 2011 13:31:12 -0400
>>> From: Garey Barrell
>>> To: Richard Knoppow<1oldlens1@ix.netcom.**com <1oldle...@ix.netcom.com>>
>>> Cc: drakelist@zerobeat.net
>>> Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
>>> (entirely)
>>> Message-ID:<4E32EE60.4060209@**mindspring.com<4e32ee60.4060...@mindspring.com>
>>> >
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>>
>>> Richard -
>>>
>>> Yes, one wonders..:-)   This type of 'dithering' is known in
>>> PTOs, but although much less
>>> common, a poor crystal oscillator such as the BAND or 2nd MIXER
>>> oscillators 'could' present the same
>>> way.
>>>
>>>
>
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>
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[Drakelist] Drake Sunday Schedule ?

[Michael A. Kelly]

Howdy,

What time and frequency is the Drake Sunday schedule?

Thanks,

Michael Kelly N4MAK
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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Garey Barrell]

Which is why subbing the Zener is the FIRST thing we check, after making sure the spring is in 
place!!  :-)


Is a three-terminal regulator such as a 78LO10 ?  a better choice??

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Dennis Monticelli wrote:
I know from my experience in the semiconductor business that zeners (especially those from a prior 
era) are notoriously noisy and can become outright unstable to varying degrees.  You will not see 
this with a DVM or other averaging type instrument.  You should put a scope on the zener and turn 
up the gain as high as the scope will go while setting the time base for anywhere from 1 to 
100ms/div.  Make sure your scope ground connection is right at the zener to keep stray pickup at a 
minimum.  If it is unstable you will see the voltage jumping around in discrete steps.  A typical 
zener will just exhibit "white" noise which looks like tall grass on the CRT.  Both the discrete 
steps and the white noise will modulate the PTO.  The steps manifest as annoying random freq 
shifts while the white noise just adds to the noise sidebands of the oscillator.  The discrete 
jumps in zener voltage are understood in the physics but unless folks are truly interested in that 
stuff I won't go into it here.
Not to scold the Drake design team (whom I respect) and maybe mostly because I witnessed how the 
sausage is actually made, but I would NEVER design a zener into a circuit as noise sensitive as an 
oscillator, mixer or preamp.   I designed and built a homebrew antenna noise bridge.  Guess what I 
used as the broadband noise source?

Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge > wrote:


Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of all, 
the K3 is deaf as a
post at 4.9 MHz ;-) but I did get enough of a signal through a scope probe 
hooked to the PTO
output to confirm that it's the PTO that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and the 
zener - even though
I'm fairly convinced the zener is okay (alright - I'll replace the 3000 pF 
first...).

I have a sneaking suspicion that this may be one of the S.A.T. caps.  If 
so, it's going to be
interesting since I no longer have a capacitance meter.

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - From: "Garey Barrell" mailto:k4...@mindspring.com>>
To: "Steve Wedge" mailto:w1es1...@earthlink.net>>
Cc: mailto:drakelist@zerobeat.net>>
Sent: Friday, July 29, 2011 3:21 PM
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors


Steve -

Yes, the PreMixer signal (V8) (BAND minus PTO) is the one that is piped 
back and forth
between the two units.

All you have to do is listen to the PTO signal itself on a separate receiver.  
"0" on the
dial = 5.455 MHz, "500" = 4.955.  The BFO crystal is 5.595 MHz.  The 
BFO is a tube, V3,
which I believe we swapped way back towards the beginning of this 
odyssey!!  I also
thought you had put a counter on the PTO, but I guess that's another 
'project'.  :-)   I
typically have three or four of these eMail projects going at one time, 
which is why I
like to keep the entire thread together.  Makes it easier to go back 
occasionally just to
review just what path got us 'here'!  :-)

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
http://www.k4oah.com/>>


Steve Wedge wrote:

You know, Garey, I've been thinking about the xtal oscillator.  It 
would have to be
part that doesn't get bandswitched - which would include THAT 
transistor.

When the T-4X controls the frequency, it sounds great and never 
jumps frequency.  In
looking at the schematic, I have been aware that the two 
solid-state oscillators (PTO
and LO for the band) get mixed in V8 (IIRC) and that this 
combination gets overridden
by the output of the T-4X's premixer.

Looks like I am going to need a counter to find out.  I am loathe 
to dig into the T-4X
because it's working so well and the PTO is much more difficult to 
remove from it due
to the volume of wires in the area.

73,

Steve, W1ES


Date: Fri, 29 Jul 2011 13:31:12 -0400
From: Garey Barrellmailto:k4...@mindspring.com>>
To: Richard Knoppow<1oldle...@ix.netcom.com 
>
Cc: drakelist@zerobeat.net 
Subject: Re: [Drakelist] R-4A PTO: It was

Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Paul Christensen]

The 78L10 is only 39-cents ea. in small quantities through Mouser.  I had 
always assumed that a Zener with current limiting resistor or in the 
alternative, a Zener with pass transistor would produce a quieter output 
than a monolithic regulator?


So, is it possible that a 78L10 may be more stable as a PTO regulator, but 
may require more in/out conditioning than a Zener?   The Fairchild 78L10 
datasheet recommends a 0.33 uF bypass on the input leg, and 0.1 uF bypass on 
the output.


Paul, W9AC

- Original Message - 
From: "Garey Barrell" 

To: "Dennis Monticelli" 
Cc: 
Sent: Saturday, July 30, 2011 2:21 PM
Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.


Which is why subbing the Zener is the FIRST thing we check, after making 
sure the spring is in place!!  :-)


Is a three-terminal regulator such as a 78LO10 ?  a better choice??

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Dennis Monticelli wrote:
I know from my experience in the semiconductor business that zeners 
(especially those from a prior era) are notoriously noisy and can become 
outright unstable to varying degrees.  You will not see this with a DVM 
or other averaging type instrument.  You should put a scope on the zener 
and turn up the gain as high as the scope will go while setting the time 
base for anywhere from 1 to 100ms/div.  Make sure your scope ground 
connection is right at the zener to keep stray pickup at a minimum.  If 
it is unstable you will see the voltage jumping around in discrete steps. 
A typical zener will just exhibit "white" noise which looks like tall 
grass on the CRT.  Both the discrete steps and the white noise will 
modulate the PTO.  The steps manifest as annoying random freq shifts 
while the white noise just adds to the noise sidebands of the oscillator. 
The discrete jumps in zener voltage are understood in the physics but 
unless folks are truly interested in that stuff I won't go into it here.
Not to scold the Drake design team (whom I respect) and maybe mostly 
because I witnessed how the sausage is actually made, but I would NEVER 
design a zener into a circuit as noise sensitive as an oscillator, mixer 
or preamp.   I designed and built a homebrew antenna noise bridge.  Guess 
what I used as the broadband noise source?

Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge > wrote:


Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of 
all, the K3 is deaf as a
post at 4.9 MHz ;-) but I did get enough of a signal through a scope 
probe hooked to the PTO

output to confirm that it's the PTO that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and 
the zener - even though
I'm fairly convinced the zener is okay (alright - I'll replace the 
3000 pF first...).


I have a sneaking suspicion that this may be one of the S.A.T. caps. 
If so, it's going to be

interesting since I no longer have a capacitance meter.

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - From: "Garey Barrell" 

>
To: "Steve Wedge" >

Cc: mailto:drakelist@zerobeat.net>>
Sent: Friday, July 29, 2011 3:21 PM
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors


Steve -

Yes, the PreMixer signal (V8) (BAND minus PTO) is the one that is 
piped back and forth

between the two units.

All you have to do is listen to the PTO signal itself on a 
separate receiver.  "0" on the
dial = 5.455 MHz, "500" = 4.955.  The BFO crystal is 5.595 MHz. 
The BFO is a tube, V3,
which I believe we swapped way back towards the beginning of this 
odyssey!!  I also
thought you had put a counter on the PTO, but I guess that's 
another 'project'.  :-)   I
typically have three or four of these eMail projects going at one 
time, which is why I
like to keep the entire thread together.  Makes it easier to go 
back occasionally just to

review just what path got us 'here'!  :-)

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
http://www.k4oah.com/>>


Steve Wedge wrote:

You know, Garey, I've been thinking about the xtal 
oscillator.  It would have to be
part that doesn't get bandswitched - which would include THAT 
transistor.


When the T-4X controls the frequency, it sounds great and 
never jumps frequency.  In
looking at the schematic, I have been aware that the two 
solid-state oscillators (PTO
and LO for the band) get mixed in V8 (IIRC) and that 

Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Garey Barrell]

I'm interested in Dennis' response to this.  Yes, it's a 'more complex' solution, but 'may' be 
quieter?  I don't know if they are more 'stable' or not.


I DO know that Zeners ARE noisy, reflected in their use as noise generators for many of the noise 
sources used for receiver and other testing.  This is especially true as they become more 'starved' 
for current, i.e., the lower the current through them, the noisier they get.  Unless Dennis shoots 
me down on that too!!  :-)


The Input and Output capacitors on the 3-term regulators are for stability, (oscillation,) rather 
than signal conditioning.


73, Garey - K4OAH
Glen Allen, VA



Paul Christensen wrote:
The 78L10 is only 39-cents ea. in small quantities through Mouser.  I had always assumed that a 
Zener with current limiting resistor or in the alternative, a Zener with pass transistor would 
produce a quieter output than a monolithic regulator?


So, is it possible that a 78L10 may be more stable as a PTO regulator, but may require more in/out 
conditioning than a Zener?   The Fairchild 78L10 datasheet recommends a 0.33 uF bypass on the 
input leg, and 0.1 uF bypass on the output.


Paul, W9AC

- Original Message - From: "Garey Barrell" 
To: "Dennis Monticelli" 

Which is why subbing the Zener is the FIRST thing we check, after making sure the spring is in 
place!!  :-)


Is a three-terminal regulator such as a 78LO10 ?  a better choice??

73, Garey - K4OAH
Glen Allen, VA


Dennis Monticelli wrote:
I know from my experience in the semiconductor business that zeners (especially those from a 
prior era) are notoriously noisy and can become outright unstable to varying degrees.  You will 
not see this with a DVM or other averaging type instrument.  You should put a scope on the zener 
and turn up the gain as high as the scope will go while setting the time base for anywhere from 
1 to 100ms/div.  Make sure your scope ground connection is right at the zener to keep stray 
pickup at a minimum.  If it is unstable you will see the voltage jumping around in discrete 
steps. A typical zener will just exhibit "white" noise which looks like tall grass on the CRT.  
Both the discrete steps and the white noise will modulate the PTO.  The steps manifest as 
annoying random freq shifts while the white noise just adds to the noise sidebands of the 
oscillator. The discrete jumps in zener voltage are understood in the physics but unless folks 
are truly interested in that stuff I won't go into it here.
Not to scold the Drake design team (whom I respect) and maybe mostly because I witnessed how the 
sausage is actually made, but I would NEVER design a zener into a circuit as noise sensitive as 
an oscillator, mixer or preamp.   I designed and built a homebrew antenna noise bridge.  Guess 
what I used as the broadband noise source?

Dennis AE6C

On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge > wrote:


Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of all, 
the K3 is deaf as a
post at 4.9 MHz ;-) but I did get enough of a signal through a scope probe 
hooked to the PTO
output to confirm that it's the PTO that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and the 
zener - even though
I'm fairly convinced the zener is okay (alright - I'll replace the 3000 pF 
first...).

I have a sneaking suspicion that this may be one of the S.A.T. caps. If so, 
it's going to be
interesting since I no longer have a capacitance meter.

Steve Wedge, W1ES/4





- Original Message - From: "Garey Barrell" mailto:k4...@mindspring.com>>
To: Richard Knoppow<1oldle...@ix.netcom.com 
>
Cc: drakelist@zerobeat.net 
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
(entirely)
Message-ID:<4e32ee60.4060...@mindspring.com 
>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Richard -

Yes, one wonders..:-)   This type of 'dithering' is known 
in PTOs, but
although much less
common, a poor crystal oscillator such as the BAND or 2nd MIXER 
oscillators 'could'
present the same
way.




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[Drakelist] RV-75 For Sale

[Don Cunningham]

Is anyone interested in buying a Drake RV-75 for your TR7??  If you are also 
running the Drake R7 with your station and are interested in the RV75, 
please let me know as I might have another item of interest to you, hi.  No 
fire sale, so don't expect it to be cheaper than I gave, but I don't want a 
fortune either.

73,
Don, WB5HAK 



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Re: [Drakelist] Drakes and temperature

[Steve Wedge]

That is certainly true that the rf impedance will be different and certainly 
a soldered connection between the frame and yoke doesn't hurt.  I may even 
wind up doing this on my receiver once I find the bad component.


I just don't think it's the problem with my PTO because there are some other 
issues still - such as it getting worse once it's really warmed-up.


I've got to get to my club-room and try and scrounge some 3000 pF or a 
couple of 1500 pF SM's


It would be nice if you could just re-cap the whole thing, but for those SAT 
components.


73,

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - 
From: "Garey Barrell" 

To: "Steve Wedge" 
Cc: 
Sent: Friday, July 29, 2011 10:11 PM
Subject: Re: [Drakelist] Drakes and temperature



Steve -

As I said earlier this evening, I'm thinking it's not just a matter of DC 
grounding of the slug.  So a clip lead is not a true replica of the ground 
braid suggested by Drake and used in all their late C-Line and all 7 Line 
PTOs.


73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Steve Wedge wrote:

Eddy -
Your problem is going to be related to one - or more - components.  As an 
ex-New Englander who used to have his shack in "the cellar", I also have 
known temperature extremes in the shack.  I don't think any "heating" or 
trying to do major modifications to the gear will resolve the root cause 
of your problem (nor mine).  This is why I've been loathe to so things 
such as running braid from the yoke to the mechanical drive frame.  I've 
tried with clip-leads just to satisfy myself. 



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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Richard Knoppow]

- Original Message - 
From: "Garey Barrell" 

To: "Paul Christensen" 
Cc: 
Sent: Saturday, July 30, 2011 12:04 PM
Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.


I'm interested in Dennis' response to this.  Yes, it's a 
'more complex' solution, but 'may' be quieter?  I don't 
know if they are more 'stable' or not.


I DO know that Zeners ARE noisy, reflected in their use as 
noise generators for many of the noise sources used for 
receiver and other testing.  This is especially true as 
they become more 'starved' for current, i.e., the lower 
the current through them, the noisier they get.  Unless 
Dennis shoots me down on that too!!  :-)


The Input and Output capacitors on the 3-term regulators 
are for stability, (oscillation,) rather than signal 
conditioning.


73, Garey - K4OAH
Glen Allen, VA

   Would not a simple RC low pass filter on the output of 
the Zener prevent the noise from affecting whatever is being 
fed by it? A filter would cure jumping from a defective 
Zener but would slow down the jumps so that they were not so 
abrupt.
   From my R4B diagram it appears that the by-passing for 
the emitter of Q-3 and source of Q-2 would smooth out any 
noise from the Zener quite a bit.
   I have not combed through this thread but has R-160 been 
checked? This is the dropping resistor for the Zener. There 
is also a 6K, 5W resistor, which does not have a designator 
on the diagram, in series with the +150V line that feeds 
both oscillator and Q-1. Unlikely but voltage there should 
be checked with a scope.
   The Zener could be eliminated by feeding the oscillator 
and buffer stages from a separate supply.
   I am also unsure after this very long thread if the 
Zener was replaced.
   If the jumping is intermittant and especially if 
temperature dependant I would be very suspicious that there 
might be a cracked trace or bad solder joint.



--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com 



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[Drakelist] Grease

[Steve Wedge]

Hmmm...

I bought some "Shinetsu" grease from a Honda dealer for the original purpose 
of lubricating the tracks of my windows in my '96 Miata and have a whole 
tube of the stuff.  Wondering it it's similar as it's completely synthetic. 
I've been looking for applications for this stuff :)


Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - 
From: 

To: 
Sent: Saturday, July 30, 2011 12:00 PM
Subject: Drakelist Digest, Vol 37, Issue 65



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Today's Topics:

  1. Re: R-4A PTO: It wasn't the transistors (entirely) (Curt Nixon)


--

Message: 1
Date: Sat, 30 Jul 2011 10:12:39 -0400
From: Curt Nixon 
To: drakelist@zerobeat.net
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
(entirely)
Message-ID: <4e341157.8080...@flash.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Jim:

I didn't know Tri-Flo came as a grease also..nice.  I do use a white
teflon grease in the bike and radios but different brand.  I have some
stuff called WGL that I cme across on the boat.  totally waterproof and
is nearly a pure teflon in grease form.  never dries up because it has
no hydrocarbon-based solvents or oils.  I use it for leadscrews, the
compensating sliders in the 390 PTO, etc.  One small can has lasted me
20 years.

Curt
KU8L



On 7/29/2011 10:54 PM, Jim Shorney wrote:

On Fri, 29 Jul 2011 10:59:53 -0400, Curt Nixon wrote:

1.  Tri-Flow is indeed a teflon-based spray lubricant.  has a distinct 
odor of amyl acetate as well..."banana oil"  It is a very nice lubricant 
for "dry" type applications.  It might be appropriate on the yoke slider 
for instance on the PTO.  Not for gears or items requiring oil.  Good 
for sliding-type applications.  Not messy.
Tri-Flow is also a PTFE-based bicycle grease. I use it all the time 
anywhere

that grease is called for in a radio. It's great stuff.

73

-Jim


--
Ham Radio NU0C
Lincoln, Nebraska, U.S.S.A.
TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, 
GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time!


"Give a man a URL, and he will learn for an hour; teach him to Google, 
and he will learn for a lifetime."


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End of Drakelist Digest, Vol 37, Issue 65
* 



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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Steve Wedge]

Interesting point, Dennis.  I also remember a noise bridge in the old ARRL 
handbook that used a zener as the noise source.

So what did you use to regulate the voltage: LM340 or similar?  Not a bad 
thought, actually...

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
  - Original Message - 
  From: Dennis Monticelli 
  To: Steve Wedge 
  Cc: k4...@mindspring.com ; drakelist@zerobeat.net 
  Sent: Saturday, July 30, 2011 12:31 PM
  Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.


  I know from my experience in the semiconductor business that zeners 
(especially those from a prior era) are notoriously noisy and can become 
outright unstable to varying degrees.  You will not see this with a DVM or 
other averaging type instrument.  You should put a scope on the zener and turn 
up the gain as high as the scope will go while setting the time base for 
anywhere from 1 to 100ms/div.  Make sure your scope ground connection is right 
at the zener to keep stray pickup at a minimum.  If it is unstable you will see 
the voltage jumping around in discrete steps.  A typical zener will just 
exhibit "white" noise which looks like tall grass on the CRT.  Both the 
discrete steps and the white noise will modulate the PTO.  The steps manifest 
as annoying random freq shifts while the white noise just adds to the noise 
sidebands of the oscillator.  The discrete jumps in zener voltage are 
understood in the physics but unless folks are truly interested in that stuff I 
won't go into it here.

  Not to scold the Drake design team (whom I respect) and maybe mostly because 
I witnessed how the sausage is actually made, but I would NEVER design a zener 
into a circuit as noise sensitive as an oscillator, mixer or preamp.   I 
designed and built a homebrew antenna noise bridge.  Guess what I used as the 
broadband noise source?

  Dennis AE6C


  On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge  wrote:

Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of all, 
the K3 is deaf as a post at 4.9 MHz ;-) but I did get enough of a signal 
through a scope probe hooked to the PTO output to confirm that it's the PTO 
that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and the 
zener - even though I'm fairly convinced the zener is okay (alright - I'll 
replace the 3000 pF first...).

I have a sneaking suspicion that this may be one of the S.A.T. caps.  If 
so, it's going to be interesting since I no longer have a capacitance meter.

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - From: "Garey Barrell" 
To: "Steve Wedge" 
Cc: 
Sent: Friday, July 29, 2011 3:21 PM
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors



  Steve -

  Yes, the PreMixer signal (V8) (BAND minus PTO) is the one that is piped 
back and forth between the two units.

  All you have to do is listen to the PTO signal itself on a separate 
receiver.  "0" on the dial = 5.455 MHz, "500" = 4.955.  The BFO crystal is 
5.595 MHz.  The BFO is a tube, V3, which I believe we swapped way back towards 
the beginning of this odyssey!!  I also thought you had put a counter on the 
PTO, but I guess that's another 'project'.  :-)   I typically have three or 
four of these eMail projects going at one time, which is why I like to keep the 
entire thread together.  Makes it easier to go back occasionally just to review 
just what path got us 'here'!  :-)

  73, Garey - K4OAH
  Glen Allen, VA

  Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
  and TR-4/C Service Supplement CDs
  


  Steve Wedge wrote:

You know, Garey, I've been thinking about the xtal oscillator.  It 
would have to be part that doesn't get bandswitched - which would include THAT 
transistor.

When the T-4X controls the frequency, it sounds great and never jumps 
frequency.  In looking at the schematic, I have been aware that the two 
solid-state oscillators (PTO and LO for the band) get mixed in V8 (IIRC) and 
that this combination gets overridden by the output of the T-4X's premixer.

Looks like I am going to need a counter to find out.  I am loathe to 
dig into the T-4X because it's working so well and the PTO is much more 
difficult to remove from it due to the volume of wires in the area.

73,

Steve, W1ES


Date: Fri, 29 Jul 2011 13:31:12 -0400
From: Garey Barrell
To: Richard Knoppow<1oldle...@ix.netcom.com>
Cc: drakelist@zerobeat.net
Subject: Re: [Drakelist] R-4A PTO: It wasn't the transistors
(entirely)
Message-ID:<4e32ee60.4060...@mindspring.com>
Content-Type: text/plain; charset=ISO-

Re: [Drakelist] Drakes and temperature

[Garey Barrell]

Steve -

Have you swapped the Zener???

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Steve Wedge wrote:
That is certainly true that the rf impedance will be different and certainly a soldered connection 
between the frame and yoke doesn't hurt.  I may even wind up doing this on my receiver once I find 
the bad component.


I just don't think it's the problem with my PTO because there are some other issues still - such 
as it getting worse once it's really warmed-up.


I've got to get to my club-room and try and scrounge some 3000 pF or a couple 
of 1500 pF SM's

It would be nice if you could just re-cap the whole thing, but for those SAT 
components.

73,

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - From: "Garey Barrell" 
To: "Steve Wedge" 
Cc: 
Sent: Friday, July 29, 2011 10:11 PM
Subject: Re: [Drakelist] Drakes and temperature



Steve -

As I said earlier this evening, I'm thinking it's not just a matter of DC grounding of the slug.  
So a clip lead is not a true replica of the ground braid suggested by Drake and used in all their 
late C-Line and all 7 Line PTOs.


73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Steve Wedge wrote:

Eddy -
Your problem is going to be related to one - or more - components.  As an ex-New Englander who 
used to have his shack in "the cellar", I also have known temperature extremes in the shack.  I 
don't think any "heating" or trying to do major modifications to the gear will resolve the root 
cause of your problem (nor mine).  This is why I've been loathe to so things such as running 
braid from the yoke to the mechanical drive frame.  I've tried with clip-leads just to satisfy 
myself. 





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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

Yes, Garey, when zeners are run at current levels near their "knee" they do
tend to be noisier. Applying this knowledge tends to give better
results with a typical zener exhibiting white noise.  But should a zener go
unstable all bets are off.

The 78L series voltage reg is zener based.  Depending upon the brand and
when it was made it may be better than a discrete zener or not.  If you go
with a 78L made in say the last 15 years, it will probably be better.  The
best choice is a voltage regulator that is based upon a "bandgap" voltage
reference.  Most linear regulators made in the last 20 years are of the LDO
(low drop out) type and these are all bandgap based.  The venerable LP2951
comes to mind.  It is a low power part with an adjustable output.  The
popular LM317 is also bandgap based and adjustable, though not LDO.  The
LM317L low power version comes in a convenient TO-92 transistor package and
may be the best physical fit for PTO service.  Any of these regs can have
their output voltage set with two resistors and will accomodate output
caps.  You can also buy linear regs that are specified for low noise, but I
think that is overkill for our needs.  We just need to avoid gross noise
issues.

Dennis AE6C

On Sat, Jul 30, 2011 at 12:04 PM, Garey Barrell wrote:

> I'm interested in Dennis' response to this.  Yes, it's a 'more complex'
> solution, but 'may' be quieter?  I don't know if they are more 'stable' or
> not.
>
> I DO know that Zeners ARE noisy, reflected in their use as noise generators
> for many of the noise sources used for receiver and other testing.  This is
> especially true as they become more 'starved' for current, i.e., the lower
> the current through them, the noisier they get.  Unless Dennis shoots me
> down on that too!!  :-)
>
> The Input and Output capacitors on the 3-term regulators are for stability,
> (oscillation,) rather than signal conditioning.
>
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
>
>
> Paul Christensen wrote:
>
>> The 78L10 is only 39-cents ea. in small quantities through Mouser.  I had
>> always assumed that a Zener with current limiting resistor or in the
>> alternative, a Zener with pass transistor would produce a quieter output
>> than a monolithic regulator?
>>
>> So, is it possible that a 78L10 may be more stable as a PTO regulator, but
>> may require more in/out conditioning than a Zener?   The Fairchild 78L10
>> datasheet recommends a 0.33 uF bypass on the input leg, and 0.1 uF bypass on
>> the output.
>>
>> Paul, W9AC
>>
>> - Original Message - From: "Garey Barrell" 
>> To: "Dennis Monticelli" 
>>
>>  Which is why subbing the Zener is the FIRST thing we check, after making
>>> sure the spring is in place!!  :-)
>>>
>>> Is a three-terminal regulator such as a 78LO10 ?  a better choice??
>>>
>>> 73, Garey - K4OAH
>>> Glen Allen, VA
>>>
>>>
>>> Dennis Monticelli wrote:
>>>
 I know from my experience in the semiconductor business that zeners
 (especially those from a prior era) are notoriously noisy and can become
 outright unstable to varying degrees.  You will not see this with a DVM or
 other averaging type instrument.  You should put a scope on the zener and
 turn up the gain as high as the scope will go while setting the time base
 for anywhere from 1 to 100ms/div.  Make sure your scope ground connection 
 is
 right at the zener to keep stray pickup at a minimum.  If it is unstable 
 you
 will see the voltage jumping around in discrete steps. A typical zener will
 just exhibit "white" noise which looks like tall grass on the CRT.  Both 
 the
 discrete steps and the white noise will modulate the PTO.  The steps
 manifest as annoying random freq shifts while the white noise just adds to
 the noise sidebands of the oscillator. The discrete jumps in zener voltage
 are understood in the physics but unless folks are truly interested in that
 stuff I won't go into it here.
 Not to scold the Drake design team (whom I respect) and maybe mostly
 because I witnessed how the sausage is actually made, but I would NEVER
 design a zener into a circuit as noise sensitive as an oscillator, mixer or
 preamp.   I designed and built a homebrew antenna noise bridge.  Guess what
 I used as the broadband noise source?
 Dennis AE6C

 On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge 
 >>> w1es1...@earthlink.net**>> wrote:

Well, it has been a long, strange trip here.

Just finished a little experiment with the PTO and my K3.  First of
 all, the K3 is deaf as a
post at 4.9 MHz ;-) but I did get enough of a signal through a scope
 probe hooked to the PTO
output to confirm that it's the PTO that is shifting frequency.

Having confirmed that, my next step will be replacing the 3000 pF and
 the zener - even though
I'm fairly convinced the zener is okay (alright - I'll replace the
 3000 pF first...).

>>

Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Dennis Monticelli]

The RC on the output of the zener trick works for white noise, but I think
the freq jumps would be just as annoying.

Dennis AE6C

On Sat, Jul 30, 2011 at 2:31 PM, Garey Barrell  wrote:

> Dennis -
>
> Well, I know "I" want to know more!  I've been out of semis so long I'm
> completely lost.  I 'know' a lot of things, (Zeners are noisy,) but didn't
> know 'why'!  An engineering brain is a terrible thing to waste...  :-)
>
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
> and TR-4/C Service Supplement CDs
> 
>
>
> Dennis Monticelli wrote:
>
>> Hi Ron,
>> Well, what we call a zener these days is actually not a zener (whose
>> breakdown mechanism is actually quantum mechanical tunneling), but rather an
>> avalanche breakdown diode.  Electrons get rippped loose by the high electric
>> fields at the PN junction interface, smack into other atoms, kick loose more
>> electrons and pretty soon you've got something akin to a snow avalanche.
>>  This is an inherantly noisy process of generating current.  When the PN
>> junction is manufactured such that the avalanching occurs at the surface of
>> the semiconductor chip that is bad for stability.  Various mobile ions
>> (often from the molding compound itself) migrate to the region of the
>> breakdown under the influence of the attractive electric field.  They
>> accumlate there and alter the breakdown characteristic.  The point of
>> avalanche then tends to flit from one region to another, each region with a
>> sightly different voltage value.  Hence the net zener voltage jumps around
>> in a random fashion.  This is in addition to the normal white noise of
>> avalanche.  The worst I've ever seen is 500mV and more typically it is a few
>> mV's or ten's of mV, but that is sufficient to shift an LC oscillator.
>> A zener diode made in a sophisticated way can avoid the instability issue
>> entirely but "burying" the PN junction below the surface of the chip.
>> Probably more than you wanted to know :-)
>> Dennis AE6C
>> On Sat, Jul 30, 2011 at 11:32 AM, Ron > wd8...@yahoo.com>> wrote:
>>
>>Dennis,
>>I would be interested in hearing more about the physics.  Not sure if
>> the rest of the list
>>would be.
>>
>>I studied Electronics, and then ended up in computers.  Kind of enjoy
>> some good old college
>>"lecture series" now and then.
>>
>>73,
>>Ron WD8SBB
>>
>>--- On *Sat, 7/30/11, Dennis Monticelli />>/*
>> wrote:
>>
>>
>>From: Dennis Monticelli > dennis.monticelli@**gmail.com >>
>>
>>Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.
>>
>>To: "Steve Wedge" > w1es1...@earthlink.net**>>
>>Cc: drakelist@zerobeat.net 
>>
>>Date: Saturday, July 30, 2011, 12:31 PM
>>
>>
>>I know from my experience in the semiconductor business that zeners
>> (especially those from
>>a prior era) are notoriously noisy and can become outright unstable
>> to varying degrees. You will not see this with a DVM or other
>> averaging type instrument.  You should put a
>>scope on the zener and turn up the gain as high as the scope will
>> go while setting the
>>time base for anywhere from 1 to 100ms/div.  Make sure your scope
>> ground connection is
>>right at the zener to keep stray pickup at a minimum.  If it is
>> unstable you will see the
>>voltage jumping around in discrete steps.  A typical zener will
>> just exhibit "white" noise
>>which looks like tall grass on the CRT.  Both the discrete steps
>> and the white noise will
>>modulate the PTO.  The steps manifest as annoying random freq
>> shifts while the white
>>noise just adds to the noise sidebands of the oscillator.  The
>> discrete jumps in zener
>>voltage are understood in the physics but unless folks are truly
>> interested in that stuff
>>I won't go into it here.
>>Not to scold the Drake design team (whom I respect) and maybe
>> mostly because I witnessed
>>how the sausage is actually made, but I would NEVER design a zener
>> into a circuit as noise
>>sensitive as an oscillator, mixer or preamp.   I designed and built
>> a homebrew antenna
>>noise bridge.  Guess what I used as the broadband noise source?
>>Dennis AE6C
>>
>>On Fri, Jul 29, 2011 at 3:25 PM, Steve Wedge <
>> w1es1...@earthlink.net
>>
>> >>
>> wrote:
>>
>>Well, it has been a long, strange trip here.
>>
>>Just finished a little experiment with the PTO and my K3.
>>  First of all, the K3 is
>>deaf as a post at 4.9 MHz ;-) but I did get enough of a signal
>> through a scope probe
>>hooked to the PTO output to confirm that it's the PTO that is
>> shifting frequency.
>>
>>Having confirmed t

Re: [Drakelist] Drakes and temperature

[Curt Nixon]

Steve Wedge wrote:
That is certainly true that the rf impedance will be different and 
certainly a soldered connection between the frame and yoke doesn't 
hurt.  I may even wind up doing this on my receiver once I find the 
bad component.


I just don't think it's the problem with my PTO because there are some 
other issues still - such as it getting worse once it's really warmed-up.


I've got to get to my club-room and try and scrounge some 3000 pF or a 
couple of 1500 pF SM's


It would be nice if you could just re-cap the whole thing, but for 
those SAT components.


73,

Steve Wedge, W1ES/4

"I can't complain, but sometimes I still do."
- Joe Walsh

If the above message appears, it came from Steve's Son of Laptop!
- Original Message - From: "Garey Barrell" 
To: "Steve Wedge" 
Cc: 
Sent: Friday, July 29, 2011 10:11 PM
Subject: Re: [Drakelist] Drakes and temperature



Steve -

As I said earlier this evening, I'm thinking it's not just a matter 
of DC grounding of the slug.  So a clip lead is not a true replica of 
the ground braid suggested by Drake and used in all their late C-Line 
and all 7 Line PTOs.


73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs



Steve Wedge wrote:

Eddy -
Your problem is going to be related to one - or more - components.  
As an ex-New Englander who used to have his shack in "the cellar", I 
also have known temperature extremes in the shack.  I don't think 
any "heating" or trying to do major modifications to the gear will 
resolve the root cause of your problem (nor mine).  This is why I've 
been loathe to so things such as running braid from the yoke to the 
mechanical drive frame.  I've tried with clip-leads just to satisfy 
myself. 



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Hi Steve:

It sounds like you have not added the braid ground on the yoke.  If not, 
yours is exactly the kind of issue it might fix.  It was a Drake 
installed mod..so a well documented fix.  It doesn't take much dust or 
crud on the yoke or the rod or the screw to upset the ground for the 
slug.  The braid solves that with a short, rf-proper path. 


Curt

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[Drakelist] Hc6u crystals

[Neil M Califano]

Quick question: Are 4 Line crystals hc6u?

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Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.

[Richard Knoppow]

- Original Message - 
From: "Dennis Monticelli" 

To: 
Sent: Saturday, July 30, 2011 2:51 PM
Subject: Re: [Drakelist] R-4A PTO: Confirmed it's the PTO.


The RC on the output of the zener trick works for white 
noise, but I think

the freq jumps would be just as annoying.

Dennis AE6C

  White noise is what I was refering to. The filter would 
slow down the rise and fall times of the jumps but not get 
rid of them, not really useful.



--
Richard Knoppow
Los Angeles
WB6KBL
dickb...@ix.netcom.com 



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