EMRFD Message Archive 1703
Message Date From Subject 1703 2008-06-13 16:33:49 bkopski A COMPONENT OF INTEREST The 365 pF air variable is a classic component and is still available
from a few suppliers. One of these is the Crystal Set Society and
the site www.midnightscience.com is worth a visit. These folks are
VERY nice to do business with friendly and speedy service is what
I've found every time.
More recently this supplier has listed a 365 pF air variable with
built in 8:1 coaxial reduction drive. I got one to play with and
decided to fit it with both "large" and "small" knobs "two speed"
drive so to speak. But this was a challenge because the coaxial
shaft arrangement has rather short shaft sections to work with.
The "inner" or direct drive shaft is less than 0.2" long while
the "outer" or slow speed drive is about 0.4" more. It's easy to
install a knob on the latter (reduced speed) shaft but quite another
thing to utilize the former. I feel both shaft sections need to be
about ½" longer than they are to allow full utility with panel
mounting ease and more practical knob options.
That notwithstanding, I set about to make a "two knob" tuning
arrangement. Some associated photos show the details. Basically, I
cut a 2 ¼" disk of double sided pc board to serve as direct
drive "inner" or large knob, or as a dial plate alternative. I used
a ¼" X 20 brass nut to mate the disk to the short part of the shaft.
The nut is drilled thru with a ¼" bit, and then the nut is cross
drilled and tapped with a 4-40 thread to accept a set screw. The nut
is then spot soldered to the pc board disc. When this combination is
installed on the "inner" or direct drive portion of the coaxial
shaft, a conventional knob can be attached to the "slow" speed shaft
portion. The result is a dual speed (two knob) tuning option.
While this HB approach is workable, I feel it is unfortunate that
this 365 pF classic with its too-short shaft arrangement makes things
so difficult. With the shaft section lengths as described, there is
not much room left to accommodate panel thickness, and the 1/16"
thick pc board "knob" is not pleasant to the touch. Nevertheless,
this appears to be a workable "workaround" and this capacitor is
destined for rapid deployment in a new HB project!
Cordially,
Bob K3NHI1704 2008-06-14 07:45:51 Doug Edwards Re: A COMPONENT OF INTEREST Hi Bob and group ! Thanks for the info on the good ole variable. Would
it be hard to take a picture of how you attatched the two knob system? I
would like to see how you worked out this problem and see if I can figuere
out another way. This would be a great part for the folks needing a tuning
cap with two rates of tuning. I am always interested in how others work out
problems both electrically and mechanically. Thanks again, 73's, 72's,
Doug, KM6OR..
On 6/13/08, bkopski <kopskirl@cavtel.net> wrote:
>
> The 365 pF air variable is a classic component and is still available
> from a few suppliers. One of these is the Crystal Set Society and
> the site www.midnightscience.com is worth a visit. These folks are
> VERY nice to do business with � friendly and speedy service is what
> I've found every time.
>
> More recently this supplier has listed a 365 pF air variable with
> built in 8:1 coaxial reduction drive. I got one to play with and
> decided to fit it with both "large" and "small" knobs � "two speed"
> drive so to speak. But this was a challenge because the coaxial
> shaft arrangement has rather short shaft sections to work with.
>
> The "inner" or direct drive shaft is less than 0.2" long while
> the "outer" or slow speed drive is about 0.4" more. It's easy to
> install a knob on the latter (reduced speed) shaft but quite another
> thing to utilize the former. I feel both shaft sections need to be
> about �" longer than they are to allow full utility with panel
> mounting ease and more practical knob options.
>
> That notwithstanding, I set about to make a "two knob" tuning
> arrangement. Some associated photos show the details. Basically, I
> cut a 2 �" disk of double sided pc board to serve as direct
> drive "inner" or large knob, or as a dial plate alternative. I used
> a �" X 20 brass nut to mate the disk to the short part of the shaft.
> The nut is drilled thru with a �" bit, and then the nut is cross
> drilled and tapped with a 4-40 thread to accept a set screw. The nut
> is then spot soldered to the pc board disc. When this combination is
> installed on the "inner" or direct drive portion of the coaxial
> shaft, a conventional knob can be attached to the "slow" speed shaft
> portion. The result is a dual speed (two knob) tuning option.
>
> While this HB approach is workable, I feel it is unfortunate that
> this 365 pF classic with its too-short shaft arrangement makes things
> so difficult. With the shaft section lengths as described, there is
> not much room left to accommodate panel thickness, and the 1/16"
> thick pc board "knob" is not pleasant to the touch. Nevertheless,
> this appears to be a workable "workaround" and this capacitor is
> destined for rapid deployment in a new HB project!
>
> Cordially,
> Bob K3NHI
>
>
>
[Non-text portions of this message have been removed]1705 2008-06-14 09:36:58 bkopski Re: A COMPONENT OF INTEREST Hi Doug,
I'm a bit confused - is it that you cannot view (open) the 4 related
photos already posted, or are you seeking additional details / photo
views? I'd be happy to supply additional photos if you can describe
more specifically what you'd like to see - just comment here or PM me
and I'll do my best!
Cordially,
Bob K3NHI
1706 2008-06-14 11:13:21 cwfingertalker Re: A COMPONENT OF INTEREST Bob,
Enjoyed the website concerning crystal radio sets. Brings back a lot
of memories. This makes me think maybe we should review where we all
buy our parts. Maybe share some ideas and experiences on part
suppliers. I have a few that I use. Mouser, Ocean State Electronics,
Kanga for kits and Dan's Small Parts for surplus parts and kits.
Bill N7EU
Sam's Valley Oregon.1708 2008-06-14 19:02:41 Doug Edwards Re: A COMPONENT OF INTEREST Hi Bob. Thanks for the reply. No, I didnt see the pic's at first, not
near the bottom of the screen as I usually see. After I looked (this time)
to the right edge of thepage where the messege was writtem I saw the 4 new
pictures added to the group photos section and low and behold, there they
are ! Please excuse my dumb witted computer skills. THe perspecive of the
cap / dial is clear as a bell now in my mind and I see the problem. It
looks like a nice handy cap though. Thanks for calling attention to them. I
will keep brain cell engaged on the problem. 73's, TKS AGN, Doug, KM6OR..
1762 2008-07-01 17:45:44 Greg Back Re: A COMPONENT OF INTEREST Bob,
I'm a little late seeing this, but a suggesti1767 2008-07-02 05:57:35 bkopski Re: A COMPONENT OF INTEREST Hi Greg, et al
TNX for the input. I've used such a lid before, but there are issues
in this case. Because the capacitor shaft(s) are so short, the lid
would have to be "inverted" (cup side out) with the inner (slow
speed) knob residing inside the outward-turned jar lid - sort of
a "knob-in-a-knob"(!). Otherwise, the capacitor body would somehow
have to be actually inside the large knob - not a mechanical nicety.
Also, my initial reaction to epoxying a brass nut to this plastic is
that of raised eyebrows - I've not had good luck with that sort of
thing previously - not sure what the story is here - may need another
look. Meanwhile, I'm trying to interest the supplier in providing
longer shafts.
Thanks again,
Bob K3NHI
1770 2008-07-02 08:37:18 tg6124 vectron TCXO use This group seems to have a wide range of knowlegable people so I figured I'd
ask here first.
I picked up a 5Mhz Vectron TXCO unit off ebay recently.
I know the power and ground pins and it works fine. It's about 1hz off
frequency according to WWV.
The adjustment screw on the unit doesn't seem to vary the oscillator frequency
at all. Is this usual?
There are two frequency adjust pins on the unit. I've hooked a potentiometer
between the pins and when I hook it up the oscillator frequency jumps up
about 2hz but changing the resistance doesn't change anything.
Do I need to hook a derived voltage across these pins instead of just a
resistor? The unit is supposed to be a 12v unit but works just fine off
13.5v.
Can I just connect 13.5 volts to the top of the pot to do a fine adjust on the
oscillator frequency?
tim ab0wr1771 2008-07-02 08:41:49 Niels A. Moseley Re: vectron TCXO use tg6124 wrote:
> This group seems to have a wide range of knowlegable people so I figured I'dWhat is the full model number of the TCXO? There might be a datasheet
> ask here first.
>
> I picked up a 5Mhz Vectron TXCO unit off ebay recently.
>
> I know the power and ground pins and it works fine. It's about 1hz off
> frequency according to WWV.
>
> The adjustment screw on the unit doesn't seem to vary the oscillator frequency
> at all. Is this usual?
>
> There are two frequency adjust pins on the unit. I've hooked a potentiometer
> between the pins and when I hook it up the oscillator frequency jumps up
> about 2hz but changing the resistance doesn't change anything.
>
> Do I need to hook a derived voltage across these pins instead of just a
> resistor? The unit is supposed to be a 12v unit but works just fine off
> 13.5v.
>
> Can I just connect 13.5 volts to the top of the pot to do a fine adjust on the
> oscillator frequency?
>
> tim ab0wr
available.
73,
Niels PE1OIT1772 2008-07-02 10:42:15 tg6124 Re: vectron TCXO use It's a Vectron 216-9135-1 Crystal Oscillator
I couldn't find a datasheet for it using Google. But I searched using the
whole model number. Maybe I should just use the first four digits?
tim ab0wr
On Wednesday 02 July 2008 10:39:49 am Niels A. Moseley wrote:
> tg6124 wrote:
> > This group seems to have a wide range of knowlegable people so I figured
> > I'd ask here first.
> >
> > I picked up a 5Mhz Vectron TXCO unit off ebay recently.
> >
> > I know the power and ground pins and it works fine. It's about 1hz off
> > frequency according to WWV.
> >
> > The adjustment screw on the unit doesn't seem to vary the oscillator
> > frequency at all. Is this usual?
> >
> > There are two frequency adjust pins on the unit. I've hooked a
> > potentiometer between the pins and when I hook it up the oscillator
> > frequency jumps up about 2hz but changing the resistance doesn't change
> > anything.
> >
> > Do I need to hook a derived voltage across these pins instead of just a
> > resistor? The unit is supposed to be a 12v unit but works just fine off
> > 13.5v.
> >
> > Can I just connect 13.5 volts to the top of the pot to do a fine adjust
> > on the oscillator frequency?
> >
> > tim ab0wr
>
> What is the full model number of the TCXO? There might be a datasheet
> available.
>
> 73,
> Niels PE1OIT1773 2008-07-02 12:09:15 Niels A. Moseley Re: vectron TCXO use > On Wednesday 02 July 2008 10:39:49 am Niels A. Moseley wrote:the
>> tg6124 wrote:
>>> This group seems to have a wide range of knowlegable people so I figured
>>> I'd ask here first.
>>>
>>> I picked up a 5Mhz Vectron TXCO unit off ebay recently.
>>>
>>> I know the power and ground pins and it works fine. It's about 1hz off
>>> frequency according to WWV.
>>>
>>> The adjustment screw on the unit doesn't seem to vary the oscillator
>>> frequency at all. Is this usual?
>>>
>>> There are two frequency adjust pins on the unit. I've hooked a
>>> potentiometer between the pins and when I hook it up the oscillator
>>> frequency jumps up about 2hz but changing the resistance doesn't change
>>> anything.
>>>
>>> Do I need to hook a derived voltage across these pins instead of just a
>>> resistor? The unit is supposed to be a 12v unit but works just fine off
>>> 13.5v.
>>>
>>> Can I just connect 13.5 volts to the top of the pot to do a fine adjust
>>> on the oscillator frequency?
>>>
>>> tim ab0wr
>> What is the full model number of the TCXO? There might be a datasheet
>> available.
>>
>> 73,
>> Niels PE1OIT
> It's a Vectron 216-9135-1 Crystal Oscillator
>
> I couldn't find a datasheet for it using Google. But I searched using
> whole model number. Maybe I should just use the first four digits?From this site (and babelfish)
>
> tim ab0wr
>
http://mpl.jp/ocxo/ocxo.html, I was able to find out that the correct
operation of the voltage control is to put a 10K potmeter from pin 5 to
GND (pins 2,3,7) and connect the wiper to pin 6.
The voltage on pin 5, which is generated by the module, should be 6.3V
during normal operation. Thus, the control voltage for frequency is pin
6, which must (apparently) be between 6.3 and 0 volts.
Hope this helps,
73,
Niels PE1OIT.1774 2008-07-02 13:12:48 Art Re: vectron TCXO use I have located specs and hookup information. That is a nice find,
especially if the price is low!
Will send file via direct email.
Regards,
Art
At 03:07 PM 7/2/2008, you wrote:
> > On Wednesday 02 July 2008 10:39:49 am Niels A. Moseley wrote:[Non-text portions of this message have been removed]
> >> tg6124 wrote:
> >>> This group seems to have a wide range of knowlegable people so I figured
> >>> I'd ask here first.
> >>>
> >>> I picked up a 5Mhz Vectron TXCO unit off ebay recently.
> >>>
> >>> I know the power and ground pins and it works fine. It's about 1hz off
> >>> frequency according to WWV.
> >>>
> >>> The adjustment screw on the unit doesn't seem to vary the oscillator
> >>> frequency at all. Is this usual?
> >>>
> >>> There are two frequency adjust pins on the unit. I've hooked a
> >>> potentiometer between the pins and when I hook it up the oscillator
> >>> frequency jumps up about 2hz but changing the resistance doesn't change
> >>> anything.
> >>>
> >>> Do I need to hook a derived voltage across these pins instead of just a
> >>> resistor? The unit is supposed to be a 12v unit but works just fine off
> >>> 13.5v.
> >>>
> >>> Can I just connect 13.5 volts to the top of the pot to do a fine adjust
> >>> on the oscillator frequency?
> >>>
> >>> tim ab0wr
> >> What is the full model number of the TCXO? There might be a datasheet
> >> available.
> >>
> >> 73,
> >> Niels PE1OIT
>
> > It's a Vectron 216-9135-1 Crystal Oscillator
> >
> > I couldn't find a datasheet for it using Google. But I searched using
>the
> > whole model number. Maybe I should just use the first four digits?
> >
> > tim ab0wr
> >
>
> From this site (and babelfish)
><http://mpl.jp/ocxo/ocxo.html,>http://mpl.jp/ocxo/ocxo.html, I was
>able to find out that the correct
>operation of the voltage control is to put a 10K potmeter from pin 5 to
>GND (pins 2,3,7) and connect the wiper to pin 6.
>
>The voltage on pin 5, which is generated by the module, should be 6.3V
>during normal operation. Thus, the control voltage for frequency is pin
>6, which must (apparently) be between 6.3 and 0 volts.
>
>Hope this helps,
>73,
>Niels PE1OIT.
>
>No virus found in this incoming message.
>Checked by AVG.
>Version: 8.0.100 / Virus Database: 270.4.3/1529 - Release Date:
>7/1/2008 7:23 PM
1775 2008-07-02 14:01:51 tg6124 Re: vectron TCXO use Thanks for the info. I truly appreciate it.
I did measure Pin 5 and it has 6.3 volts standing on it.
I tied this to the top of a 10k pot, tied the bottom of the pot to ground, and
took the slider of the pot to Pin 6. It works perfectly! I can tune the
frequency so I have fewer than three beats per 60seconds so that is actually
more accuracy than I should ever need.
I appreciate everyone's help. 73,
tim ab0wr
On Wednesday 02 July 2008 02:07:15 pm Niels A. Moseley wrote:
> From this site (and babelfish)
> http://mpl.jp/ocxo/ocxo.html, I was able to find out that the correct
> operation of the voltage control is to put a 10K potmeter from pin 5 to
> GND (pins 2,3,7) and connect the wiper to pin 6.
>
> The voltage on pin 5, which is generated by the module, should be 6.3V
> during normal operation. Thus, the control voltage for frequency is pin
> 6, which must (apparently) be between 6.3 and 0 volts.
>
> Hope this helps,
> 73,
> Niels PE1OIT.