Re: 10 MHz reference inputs
I've never seen ics sanded on equipment from reputable manufacturers. It's always the marginal fly-by-nights.
The IC numbers have been visible in every Extron DA that I've looked at. No reputable OEM removes common part numbers. Even if they did, there aren't that many ICs designed for this application.
I remember the first IC designed for Video. It was introduced around 1988 and barely handled NTSC video. It was disappointing that the frequency response was so poor. I could have used a couple dozen at the TV station? where I was working in Engineering. On top of poor specs, I couldn't even buy a sample to test in our shop. The first video DAs that I worked on were early, discrete Grass Valley which were fully documented. All of the Extron DAs that I have came with a large clear label on the bottom with basic information on how to use them.
Link to Extron manual:
There are plenty of these on Ebay.
For Michael A. Terrel, be aware that many US manufacturers sand the numbers off ICs and transistorls.
For Leon Robinson, given your opinion of politicians, which I agree with, you might like:
? [aka Lone star planet]
"Apparently, on New Texas, killing a politician wasn't regarded as?mallum in se, and was?mallum prohibitorum?only to the extent that what happened to the politician was in excess of what he deserved.?"
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Re: 10 MHz reference inputs
The IC numbers have been visible in every Extron DA that I've looked at. No reputable OEM removes common part numbers. Even if they did, there aren't that many ICs designed for this application.
I remember the first IC designed for Video. It was introduced around 1988 and barely handled NTSC video. It was disappointing that the frequency response was so poor. I could have used a couple dozen at the TV station? where I was working in Engineering. On top of poor specs, I couldn't even buy a sample to test in our shop. The first video DAs that I worked on were early, discrete Grass Valley which were fully documented. All of the Extron DAs that I have came with a large clear label on the bottom with basic information on how to use them.
Link to Extron manual:
There are plenty of these on Ebay.
For Michael A. Terrel, be aware that many US manufacturers sand the numbers off ICs and transistorls.
For Leon Robinson, given your opinion of politicians, which I agree with, you might like:
? [aka Lone star planet]
"Apparently, on New Texas, killing a politician wasn't regarded as?mallum in se, and was?mallum prohibitorum?only to the extent that what happened to the politician was in excess of what he deserved.?"
|
I suspected the phase meter was too simple. I searched for frequency comparison using a 4046PLL but couldn't find anything. I'll look again Monday.
h
This compares frequencies with very high sensitivity. Is it too complex for your needs ?
?
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No, the Elektor circuit is a phase meter. It shows the instantaneous phase difference between two signals. If the frequencies are different, the phase will be continuously changing. The meter needle will be swinging back and forth from min to max at the frequency difference of the two signals. Useful only when the frequency difference is low enough you can tell changes in the speed of the needle movement to tell if you are adjusting the frequency difference to closer or further apart.
The phase meter is useful when the frequency difference is very small - adjust the unknown freq so that it's phase compared to the reference is unchanging. doesn't need to be 0, just unchanging. At that point, the freqs are equal.
An oscilloscope can be used as a phase meter. View the unknown freq, using the GPS oscillator as an external trigger, and set the sweep speed to show only a couple of cycles on the screen. If the frequencies are unequal the signal will be drifting across the screen, If the display is drifting from left to right, the unknown freq is lower in freq than the reference. Right to left would be higher. This can also be used for harmonically related signals such as adjusting a 5 MHz signal using a 10 MHz reference.
John
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On 9/10/2022 10:08 AM, Jeff Green wrote: ?----------------------------------------------------------------------------------
At the risk of showing the world just how vast my ignorance is, will this circuit allow me to compare the 10MHz from a GPS disciplined oscillator and a 10MHz "Precision double oven OCXO" and produce an error voltage proportional to the frequency difference?
_._,_._,_
------------------------------------------------------------------------
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Re: 10 MHz reference inputs
I used an Extron dist amp for mine. I had seen a youtube video of someone making the conversion for his rubidium source, I just adapted it to my GPSDO (the Russian one).
It's so far been working fine 24/7 for at least 2 years now.
Vince - K8ZW.
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On 09/10/2022 03:38 PM, Michael A. Terrell wrote: I'm not familiar with that model number. It appears to be a low end VGA
amplifier of three 80MHz channels with four outputs per channel. It
looks like at least two versions were built. Both have a toggle swich o
terminate the inputs with 75 ohms, or to let you loop the inputs to
another unit or channel.
The fourth channel is low frequency, for composite sync only.
I contacted Exatron a few years ago about their analog video DAs. One of
their engineers gave me the typical, "Our equipment is too complex to
service outside the factory." when I asked about a schematic.
Find the datasheet for the ICs they used in that model. You can easily
understand their designs with the pinout and typical circuit drawings on
the Datasheet.
On Sat, Sep 10, 2022 at 2:21 PM Leon Robinson
<leon-robinson@... <mailto:leon-robinson@...>> wrote:
Leon Robinson K5JLR
Is anyone familiar with the Extron ADA 3 80 RBGS distribution amp
and havea manual for it.
*Political Correctness is a Political Disease.*
*Politicians and Diapers should be changed
often and for the same reasons.*
On Saturday, September 10, 2022, 09:43:03 AM CDT, Kuba Ober via
groups.io <> <kuba@...
<mailto:[email protected]>> wrote:
> now I'm faced with a new twist, a single connector marked 10 MHz
In/Out These units let you manually select ext or internal, but if
the ref goes away for a moment, or the power is lost, the SG
switches back to internal without notifying you, AND forces it's
internal 10 MHz out on the cable, which distorts and beats against
the 10 MHz being supplied, potentially screwing up any other
instruments on that feed!
>
> This seems totally insane to me.
It is insane (I’m looking at you, Siglent). Someone thought they’ll
be very clever by saving a BNC connector. Probably a beancounter
idea, although this may be giving them too much credit.
Once this hack appeared on some popular model, other companies
started copying it without any thought given.
Cheers, Kuba
--
Michigan VHF Corporation -- nobucks dot net
K8ZW -
Etsy Shop:
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On Fri, Sep 9, 2022 at 01:26 PM, Jeff Green wrote:
Is there any easy way to convert the difference frequency to a voltage with positive local TXCO frequency producing a positive voltage and lower local TXCO frequency producing a negative voltage?
Hi, Max described a good solution. But FWIW, another way to do it more discretely is like this: - GIVEN that the signal is a relatively low-frequency square wave. - Use a diode and cap in series to create narrow pulses on the rising edge of the square (but not on the falling edge). The idea is that the pulses will all be the same width, whereas the pulses from the original square wave will vary in width. The series cap is acting like a high-pass filter, creating narrow pulses from wide pulses. The diode is so that you DON'T get negative pulses on the falling edges. - Use the equal-width pulses to charge a larger cap. The charge on this cap varies with the frequency of the pulses, and it is acting like a low-pass filter or integrator. So the voltage across the cap is related to the frequency of the pulses. - Connect a mechanical meter across the cap. Preferably a sensitive meter, say 50uA. - Note that you don't necessarily need the 2nd cap at all - the mechanical inertia of the meter also acts as a LP filter! So in theory, the entire circuit could be nothing but a diode and cap in series with a meter. It's not a precise method, but very simple. The scheme described is how old-school Geiger counters drove the meter - the faster the pulses from the Geiger tube, the higher the meter indication. Note that getting a "zero-center" meter indication is a problem with a simple setup like mine, because the difference frequency does NOT tell you if it's high or low. Pete
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Re: 10 MHz reference inputs
I think I like a ground lift switch. Set for min common mode signals. Some where I saw or read about grabbing old lan cards. Each one has filters (band pass) and transformers. All set to work at 10 MHz. I have 2 rubidium oscillators.?
At Tek Country store I bought the 10 MHz ref distribution system. Project boxes with unknown guts.
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Re: 10 MHz reference inputs
I'm not familiar with that model number. It appears to be a low end VGA amplifier of three 80MHz channels with four outputs per channel. It looks like at least two versions were built. Both have a toggle swich o terminate the inputs with 75 ohms, or to let you loop the inputs to another unit or channel. The fourth channel is low frequency, for composite sync only.
I contacted Exatron a few years ago about their analog video DAs. One of their engineers gave me the typical, "Our equipment is too complex to service outside the factory." when I asked about a schematic. Find the datasheet for the ICs they used in that model. You can easily understand their designs with the pinout and typical circuit drawings on the Datasheet.
Leon Robinson ?? K5JLR
Is anyone familiar with the Extron ADA 3 80? RBGS distribution amp and havea manual for it.
Political Correctness is a Political Disease.
Politicians and Diapers should be changed
often and for the same reasons.
On Saturday, September 10, 2022, 09:43:03 AM CDT, Kuba Ober via <kuba= [email protected]> wrote:
> now I'm faced with a new twist, a single connector marked 10 MHz In/Out? These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed!
>?
> This seems totally insane to me.
It is insane (I’m looking at you, Siglent). Someone thought they’ll be very clever by saving a BNC connector. Probably a beancounter idea, although this may be giving them too much credit.
Once this hack appeared on some popular model, other companies started copying it without any thought given.
Cheers, Kuba
|
Re: 10 MHz reference inputs
Leon Robinson ?? K5JLR
Is anyone familiar with the Extron ADA 3 80? RBGS distribution amp and havea manual for it.
Political Correctness is a Political Disease.
Politicians and Diapers should be changed
often and for the same reasons.
On Saturday, September 10, 2022, 09:43:03 AM CDT, Kuba Ober via groups.io <kuba@...> wrote:
> now I'm faced with a new twist, a single connector marked 10 MHz In/Out? These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed!
>?
> This seems totally insane to me.
It is insane (I’m looking at you, Siglent). Someone thought they’ll be very clever by saving a BNC connector. Probably a beancounter idea, although this may be giving them too much credit.
Once this hack appeared on some popular model, other companies started copying it without any thought given.
Cheers, Kuba
|
Re: 10 MHz reference inputs
Sorry for being stupid, I am not a big RF dude.
But at 10MHz, IMHO, one can run this over a schottky diode?
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 21k4 other followers by visiting the Crazy Electronics Lab at
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On 2022. 09. 10. 16:42, Kuba Ober via groups.io wrote: now I'm faced with a new twist, a single connector marked 10 MHz In/Out These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed!
This seems totally insane to me. It is insane (I’m looking at you, Siglent). Someone thought they’ll be very clever by saving a BNC connector. Probably a beancounter idea, although this may be giving them too much credit.
Once this hack appeared on some popular model, other companies started copying it without any thought given.
Cheers, Kuba
|
Re: 10 MHz reference inputs
now I'm faced with a new twist, a single connector marked 10 MHz In/Out These units let you manually select ext or internal, but if the ref goes away for a moment, or the power is lost, the SG switches back to internal without notifying you, AND forces it's internal 10 MHz out on the cable, which distorts and beats against the 10 MHz being supplied, potentially screwing up any other instruments on that feed!
This seems totally insane to me. It is insane (I’m looking at you, Siglent). Someone thought they’ll be very clever by saving a BNC connector. Probably a beancounter idea, although this may be giving them too much credit. Once this hack appeared on some popular model, other companies started copying it without any thought given. Cheers, Kuba
|
Hi Mikek,
Correct, X axis is units of MHz.
Y axis is volts at one turn side of 50:1 injection transformer. At 10
MHz marker, injection voltage = 1V / 50 = 20mV.
Power applied to 50 turn side is 0.02W = 1V into 50 ohm load.
John KN5L
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On 9/10/22 8:44 AM, Mikek wrote: Could you explain the graph to me? I assume G.MHz is 1 MHz.
What is the Y axis? Is it the output impedance of the secondary in
milliohms?
??????????????????????????? Thanks, Mikek
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Could you explain the graph to me? I assume G.MHz is 1 MHz.
What is the Y axis? Is it the output impedance of the secondary in milliohms?
??????????????????????????? Thanks, Mikek
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Re: 10 MHz reference inputs
A little known sometimes obtainable older device is the Spectracom 8140 frequency distribution amplifier.? It s somewhat different in that it uses remote boxes called “Line Taps” that are placed in the locations where you need the 10 MHz reference signal.
?
The 8140 itself has 4 outputs that also have a DC supply voltage superimposed on the 10 MHz signal that is used by each line tap to power its internal circuitry.? All 4 outputs can drive up to 25 line taps in a daisy chained configuration at distances up to 750 to 1500 feet using RG-58 cable.? Each line tap takes its signal utilizing a BNC tee connected to the cable at each location.
?
I was fortunate enough to pick up an 8140 plus 20 line taps.? Although the distance isn’t an issue here it is nice to have if you need to obtain the 10 MHz somewhere else other than your shop or lab.
?
There’s a neat feature of a selectable frequency output BNC on the front panel of the 8140 itself that allows you to obtain 100 kHz, 1 MHz, 5 or 10 MHz signals.? Use of this feature does not affect the standard 10 MHz signals coming out of the line taps.
?
In addition I also use an HP 5087A for the nearby items on my calibration bench.
Greg
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Hi Jeff. ? As compared to what I understand you want I think the answer you got from SCMenasian ?is overkill raised to the Nth power.? The phase/frequency detector in the 4046 CMOS phase lock loop will do exactly what you want.? It produces an output voltage that goes from 0 to Vcc but you can return the other side of the meter to a voltage divider producing ? Vcc.? You connect the two inputs to the two sources not after the mixer. ? 73 (Regards). ? Max K 4 O D S. ? I've Never Lost the Wonder. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jeff Green
Sent: Friday, September 09, 2022 2:26 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] clock calibrator ? In: saipan59 (Pete) Aug 2???#1?? ? A gadget that I built a couple of years ago.?
The purpose is to compare an unknown freq to the output of a GPSDO, so that the unknown can be tweaked to match.
It's only useful when the unknown's freq is rather close to a known value.
The circuit does an AND of the GPSDO output with the unknown, thus "mixing" the two signals, then a small MCU measures the difference freq. ---------------------------------------- Please don't laugh. Is there any easy way to convert the difference frequency to a voltage with positive local TXCO frequency producing a positive voltage and lower local TXCO frequency producing a negative voltage? ? I could use this to drive a zero center pointer meter to display error. ? Thank you
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Re: 10 MHz reference inputs
The isolation transformer may have
converted the square wave to a sine wave.
?
Paul, W8AEF
?
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From: [email protected]
[mailto:[email protected]]
On Behalf Of si_emi_01
Sent: Friday, September 09, 2022
5:29 PM
To: [email protected]
Subject: Re: [Test Equipment
Design & Construction] 10 MHz reference inputs
?
Hi
Jeff,
?
You
are aware that the Leo Bodnar GPS Device is a Square Wave Output?
?
What
does the waveform look like on an Oscilloscope with a 50 Ohm Load?
?
Ross
?
?
I have
a Signal Hound USB-SA44B that will accept an external 10MHz reference.
I
tested the output of my GPS DO,
.
?
I
connected it directly and through a BN73-202 1:1 isolation transformer. It
worked fine with 4 turns to 4 turns and it works fine both ways.
?
?
I have
no idea how critical other devices are.
?
A
member of our SW club suggested I check this link:
/g/UKMicrowaves/topic/10mhz_buffer_amplifier/69387345?p=
There
are several links there that look promising.
Scroll
down there are 4 and 10 output amps.
And
this one features transformer isolation on all the outputs.
?
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Re: 10 MHz reference inputs
Hi Jeff, ? You are aware that the Leo Bodnar GPS Device is a Square Wave Output? ? What does the waveform look like on an Oscilloscope with a 50 Ohm Load? ? Ross ?
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From: [email protected] < [email protected]> On Behalf Of Jeff Green Sent: Friday, September 09, 2022 5:26 PM To: [email protected]Subject: Re: [Test Equipment Design & Construction] 10 MHz reference inputs ? I have a Signal Hound USB-SA44B that will accept an external 10MHz reference. I tested the output of my GPS DO, . ? I connected it directly and through a BN73-202 1:1 isolation transformer. It worked fine with 4 turns to 4 turns and it works fine both ways. ? ? I have no idea how critical other devices are. ? A member of our SW club suggested I check this link: /g/UKMicrowaves/topic/10mhz_buffer_amplifier/69387345?p= There are several links there that look promising.
Scroll down there are 4 and 10 output amps. And this one features transformer isolation on all the outputs.
?
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Attached is SimSmith model for T68-2 50T Injection Transformer low
frequency limit. Source is set to 0.02W = 1V. L.V.M trace is injection
transformer voltage.
John KN5L
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Re: 10 MHz reference inputs
Hi Jeff, ? I think that should work. The calculator on Toroids.info doesn’t give me the correct answer. ? The Material does have a high AL, though. It shouldn’t saturate with 50 Ohms with a 5V applied source. The 50 Ohm Parallel Resistive Destination Termination should set the Impedance for the System. If it is not a good match, it will reflect back into the source. ? Give it a try and see if the losses and mismatch are what you can live with. ? ? Ross ? ? ?
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From: [email protected] < [email protected]> On Behalf Of Jeff Green Sent: Friday, September 09, 2022 2:35 PM To: [email protected]Subject: Re: [Test Equipment Design & Construction] 10 MHz reference inputs ? Could a 1:1 RF isolation transformer based on 4T:4T wound on a BN73-202 work in place of the Mini-Circuits FTB-1-1+? ? There is nothing magic about the B73-202, I happened to have a dozen on hand. I use these to isolated my shortwave receivers. ? Jack Smith, owner or Clifton Labs, offered this design:
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Re: 10 MHz reference inputs
Hi, ? Most Distribution Amplifiers have one Input and several Outputs. When connected to multiple devices, you want good isolation both filtering and galvanic. It is very easy to run into a Ground Loop between instruments OR Other Items attached to the equipment set up (like an EUT) or even a chamber wall. Here are a few ideas for preventing that problem… ? ? HP5087A - Distribution Amplifier ------------------------------------------ A good older inexpensive Distribution Amplifier is the HP5087A with the 10MHz Input and 12 Isolated 10MHz Outputs. They were configurable when they were ordered. ? It has 3 separate Inputs Options. Option 31 has a 5MHz, 1MHz, and 100kHz Inputs. They split out to 4 each 5MHz Outputs, 4 each 1MHz Outputs, and 4 each 100kHz Outputs. ? Option 32 has one 5 MHz Input and 12 each 5MHz Outputs. ? Option 33 has one 10MHz input and 12 each 10MHz Outputs. ? Option 34 has one 5MHz Input that splits out to 4 each 5MHz Outputs, and includes a divider chain to provide 4 each 1MHz Outputs and 4 each 100kHz Outputs. ? If you see one for sale, make sure it has the Frequencies that you want. ? Each of the 12 Output Amplifier Modules include Filtering for High Isolation and purity. They also include independent Power Filtering, Phase-matched Push-Pull Output Amplifiers with Tuned-Output Transformer Coupling capable of at least 5V P-P Signal Levels into 50 Ohm Loads. Each Output is independently adjustable from 0 to 3V RMS. A Switchable Panel Meter shows the selected level of each output. ? Each Output is independently adjustable from 0 to 3V RMS into 50 Ohms. Other specifications include Load Isolation of 50dB minimum, SSB Phase Noise is down 145dB , Channel-to-Channel Crosstalk is down 60dB and Non-Harmonic content is down 80dB. ? One thing to be aware of is that this device and the Fluke device listed below do not galvanically isolate the outputs. Some of that is to control EMI, some to establish the Distribution Amplifier as the Master Ground. You may run into a Ground Loop situation. If that occurs, refer to the information on the Mini-Circuits Isolation Transformer listed below. I have used the Mini-Circuits solution effectively many times to solve a Reference Distribution Ground Loop Issue. ? ? Fluke 203A - Distribution Amplifier ---------------------------------------------- HP also made a rebranded Fluke 203A. It has the same options and specifications. ? ? Argo Systems AS-211 ---------------------------- Another good option is an Argo Systems AS-211. This is my 10MHz House Reference and Distribution Amplifier. It includes an Efratom FRK Rubidium Source, Independent Filtered Power, Filtered and Isolated Output Channels. It works very well and the FRK can be GPS Disciplined. I like it a lot. ? It can also be configured (Modified), to have an external reference (like a GPS Disciplined OCXO input), to be an input instead of the FRK and Output to the Distribution Amplifier. ? ? Video Distribution Amplifiers --------------------------------------- Lots of other less expensive Distribution Amplifiers out there. I tried the Video Box thing and wasn’t satisfied. Some of these I have heard work well. ? ? 10 Base-T Ethernet Transformers ------------------------------- By the way, the Old Ethernet 10 Base-T Output Transformers on Ethernet PC Cards can work to Isolate each Output from others. ? ? Ground Loop Isolation Transformer ----------------------------------------------- Mini-Circuits also makes a really good Isolation Transformer FTB-1-1+ that provides very high isolation. ? These can be used to solve individual Equipment and System-wide Ground Loops. It is a 200kHz to 500MHz Full Isolation Transformer. It breaks the galvanic return path of the equipment or Reference Distribution System. It forces the offending equipment to stay on its own Ground Return or Earth Return. ? You can isolate one equipment or a string of equipment. It can also help break the Return Path for Equipment Under Test (EUT) situations. ? It is BNC FM In and BNC FM Out. They also make a Male/Female version too. You just patch it in place. ? ? ? My opinions only. Good luck. ? Ross ? ? ?
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From: [email protected] < [email protected]> On Behalf Of Greg Muir via groups.io Sent: Thursday, September 08, 2022 11:38 AM To: [email protected]Subject: Re: [Test Equipment Design & Construction] 10 MHz reference inputs ? What piece of equipment do you have that puts the 10 MHz reference back out of the external input jack when on internal mode?? I have a large number of units that are locked to my lab standard through a distribution amp but they all have separate input/output jacks.? Have never seen one jack used for both.
Greg
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Michael A. Terrell
John Kolb
saipan59 (Pete)
