Re: HP boxes: direction of air flow
The filter foam is called reticulated foam. It's sometimes sold as fish filter foam (even though that's filtering water) but it doesn't follow that all fish filter foam is usable for air filters. It's also sometimes used to face loudspeakers.
I found a wide selection of it in the Bauhaus store in Berlin a few years ago. Unfortunately I've used up my stocks. If any reader is near there, they could do a great service to us all by putting some on ebay - what's there is mostly unsuitable.
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Re: HP boxes: direction of air flow
The filter foam is called reticulated foam. It's sometimes sold as fish filter foam (even though that's filtering water) but it doesn't follow that all fish filter foam is usable for air filters. It's also sometimes used to face loudspeakers.
I found a wide selection of it in the Bauhaus store in Berlin a few years ago. Unfortunately I've used up my stocks. If any reader is near there, they could do a great service to us all by putting some on ebay - what's there is mostly unsuitable.
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Re: HP boxes: direction of air flow
You can buy it on Ebay, and from industrial suppliers.
On Tue, Nov 14, 2023 at 12:12?PM Tom via Metronet < n8zmTWH@...> wrote: Probably because the filter material degraded with age and fell apart; then was not replaced. Can¡¯t suggest where to get it or what alternatives there might be. It may also have a slight benefit in reducing the jet engine noise typical of HP fans. ? Tom, N8ZM ? ? Indeed, the dust filter is a good argument.
My box only has a finger grid, though, no dust filter, but lots of dust inside...
Tom
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I did extensive numerical studies and found I could invert the 1D heat equation for multiple flows such that the prediction accuracy was 1-2% error for a period equal to the recorded data. That assertion generated all the controversy I was involved in. I just wanted to demonstrate that I reliably forecast the drift. For that I need a signficiant amount of multichannel data. No one would provide any so I'm building my own system to compare 40 new and 40 old LM317s voltage references over time in immediate proximity in an environmentally controlled chamber.
The dominant source of initial drift is the thermo-viscous relaxation of the wirebond strains. Diffusion is probably next, but you can only peel the onion one layer at a time.
But I finished lunch and need to get back to clearing the clutter out my shop s1500 sq ft tp get it properly lighted and wired and my long delayed screen room built.
Have Fun!
Reg
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Re: HP11729C 640 MHz magic cable?
Hi Robin,
I built such a cable. As you said output is 11dBm-13dBm, input is 1dBm-4dBm level. Cable needs to provide ~ 9dB attenuation so that the output after going through attenuator provides >=1dBm and <=4dBm.?
Length (phase) of the cable is critical. There is a very sharp 640MHz filter and phase should be exactly right otherwise it won't oscillate. To get an idea I fed in 640MHz with a splitter and measured the phase of input signal vs output signal at the oscillation frequency. It was ~ 1.6ns (wasn't a super accurate measurement).
I built a 9dB attenuator, and cut a coax to approximate length, then with trimming the coax I tuned it for 640MHz. I also built a tap off from the attenuator so that I can measure the frequency. I can send pictures if it is useful.?
Ozan
On Tue, Nov 14, 2023 at 08:58 AM, Robin Szemeti wrote:
Hi,
I have an HP 11729B that looks an anwful lot more like an 11729C, complete with the 640 MHz input (BNC) and output (SMA) ... as you may know you can apparently link these two together to use an "interanal 640 MHz" to drive the comb filter generator.
It's not actually an oscillator output to feed the amp input, but the aux output of the 640 MHz power amp, at about +12 dBm .. fed through a suitable attenuator back to the input it self-oscillates (or is supposed to) at around the peak of the input tuned filter.?? I've tried with a 10dB pad and a 5dB pad ... both of which should be enough to cause it to oscillate,? its would get around 2.5 dBm at the input, which is sufficent drive, assuming the phsae shift is there or therabouts. any other clues as to what the approx value of the HP magic cable attenuator is?? The part number is? HP 11729-60096 or 11729-60098? but I can find no further info on it.? Maybe it is just a series capacitor or something?
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Re: HP boxes: direction of air flow
Probably because the filter material degraded with age and fell apart; then was not replaced. Can¡¯t suggest where to get it or what alternatives there might be. It may also have a slight benefit in reducing the jet engine noise typical of HP fans. ? Tom, N8ZM ?
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From: [email protected] <[email protected]> On Behalf Of tom_iphi via groups.io
Sent: Tuesday, November 14, 2023 11:57 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP boxes: direction of air flow? Indeed, the dust filter is a good argument.
My box only has a finger grid, though, no dust filter, but lots of dust inside...
Tom
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Thanks to all. I did not expect nor rely upon WD-40. Kroil ordered arrives on the 20th. Appreciate the recommendations re the knob and, unless Kroil or other method to extract the set screw is successful, I will have to replace the knob. Have a friend who has a collection of HP and Tek equipment wherein I could appropriate a "look-alike". But, that said, there's no sense getting in a hurry over this. The unit's clean and appears to be somewhat accurate so I'd like to restore it to use..along with my Fluke 1920A, a Sampo counter, and two Optoelectronics 7010s -- one of which is plugged into my 7704A as an ersatz frequency readout after the 7D14 and 7D15 plug-ins died.I guess this old gear just leaps out and Velcros themselves to me.? That said, the TIME GATE/DELAY knob is "sano". The stuck knob is the A channel sensitivity control so I would not want to hack up the control but am willing to sacrifice the knob. And thanks to Robert on the pot replacement. I note that the original has six solder points. Obviously one pair of three are the wiper and high/low posts. Dunno what the other three are nor which set is which. I am willing to settle for the normal unswitched adjustment and sacrifice the "hold". Unfortunately, I cannot find? the schematics anywhere. The stock manuals only go up to chapter 7, schematics are in 8. Would appreciate anyone having a copy passing it along. If it takes USPS, I will gladly reimburse. Sincerely grateful for all the advice and I will definitely keep the group posted., -- William, k6whp -------------------- "Cheer up, things could get worse. So I cheered up and things got worse."
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Kroil, or Kano Kroil, is a very good
penetrating oil that has been around for decades. If the knob is
Bakelite or other material that will not melt, turn the setscrew
hole upward, put a couple drops of synthetic engine oil in the
hole, and then heat it? with a soldering iron that has a small
tip. Then try to loosen the setscrew. If the knob has two
setscrews and you can get one out, put the penetrating oil in
the vacant screw hole as well. Many times there is a steel
setscrew in a brass knob insert pressing on an aluminum shaft.
Add a bit of moisture and weird things happen.
??? Bruce Gentry, KA2IVY
On 11/14/23 11:00, Steve Hendrix wrote:
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On
2023-11-14 09:57 AM, Joel Setton wrote:
Put a drop of oil (not WD-40) into the
threaded hole and let it soak its way in for 24 hours.
FWIW, somebody on this group or the Tek group recommended a
product called Kroil a while back. I bought some to try on a
couple things I knew were going to be impossible to unscrew - and
it worked like a champ. Good stuff, and worth a try here!
Steve Hendrix
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HP11729C 640 MHz magic cable?
Hi,
I have an HP 11729B that looks an anwful lot more like an 11729C, complete with the 640 MHz input (BNC) and output (SMA) ... as you may know you can apparently link these two together to use an "interanal 640 MHz" to drive the comb filter generator.
It's not actually an oscillator output to feed the amp input, but the aux output of the 640 MHz power amp, at about +12 dBm .. fed through a suitable attenuator back to the input it self-oscillates (or is supposed to) at around the peak of the input tuned filter.?? I've tried with a 10dB pad and a 5dB pad ... both of which should be enough to cause it to oscillate,? its would get around 2.5 dBm at the input, which is sufficent drive, assuming the phsae shift is there or therabouts. any other clues as to what the approx value of the HP magic cable attenuator is?? The part number is? HP 11729-60096 or 11729-60098? but I can find no further info on it.? Maybe it is just a series capacitor or something?
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Re: HP boxes: direction of air flow
Indeed, the dust filter is a good argument.
My box only has a finger grid, though, no dust filter, but lots of dust inside...
Tom
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
On 2023-11-14 09:57 AM, Joel Setton wrote: Put a drop of oil (not WD-40) into the threaded hole and let it soak its way in for 24 hours. FWIW, somebody on this group or the Tek group recommended a product called Kroil a while back. I bought some to try on a couple things I knew were going to be impossible to unscrew - and it worked like a champ. Good stuff, and worth a try here! Steve Hendrix
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Re: HP boxes: direction of air flow
It is quite common for the casing to have ¡®positive¡¯ pressure in order to keep any foreign bodies out unless they are filtered through Any grille/filter foam mesh etc. ? HIH Regards Nigel ?
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From: [email protected] <[email protected]> On Behalf Of Harke Smits via groups.io
Sent: Tuesday, November 14, 2023 3:15 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP boxes: direction of air flow? Hello Tom, ? Normally outside in as far as I know. The fan will not blow against a dust filter, will it? Cheers, Harke On 14/11/2023 15:48, tom_iphi via groups.io wrote: Hi folks,
is there a general rule for HP boxes with fan how the airflow is routed?
Does the fan blow air into the box or suck it out of the box?
I have a 8517 with missing fan, so I need to know...
Thanks, Tom
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Re: HP boxes: direction of air flow
Hello Tom,
Normally outside in as far as I know. The fan will not blow
against a dust filter, will it?
Cheers,
Harke
On 14/11/2023 15:48, tom_iphi via
groups.io wrote:
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Show quoted text
Hi folks,
is there a general rule for HP boxes with fan how the airflow is
routed?
Does the fan blow air into the box or suck it out of the box?
I have a 8517 with missing fan, so I need to know...
Thanks, Tom
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Hi William,
Been there, done that -- but IMHO WD-40 is not the best choice. Its main use is a water repellent.
I would do this :
- Try to get any grease, etc ... out of the thread with a little IPA and a blow of compressed air.
- Then, orient the instrument so that the screw is above the shaft
- Put a drop of oil (not WD-40) into the threaded hole and let it soak its way in for 24 hours. You can use regular motor oil for that.
Then hope for the best ... and give it a try with any tool which will fit the (damaged) screw.
After that ... do let us know !
IHTH
Joel
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HP boxes: direction of air flow
Hi folks,
is there a general rule for HP boxes with fan how the airflow is routed?
Does the fan blow air into the box or suck it out of the box?
I have a 8517 with missing fan, so I need to know...
Thanks, Tom
|
Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Unfortunatly the pot with switch has been discontinued by Bourns. Last one I repaired I managed to make one up using a switched pot of the wrong resistance value and the resistance track off a 470k non-switched pot. IIRC the switched pot came off a TENS unit that was in a box of parts that was part of a auction lot I bought for something else in the lot.?
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
William, on the buggered setscrew, I will relate what has worked for me - occasionally! I grab a piece of hard steel, like the tang of a small file or - my favorite - one of the old-style square cut concrete nails (they are harder than superman's kneecap), and I grind a tapered 3 or 4-sided profile on it. The goal is to fashion a tapered tool that can be tapped into the opening of the setscrew, with the ground edges cutting into setscrew to gain a little purchase. If you hold your mouth just right and the gods are smiling, you can apply a little torque to the destroyed fastener and get it moving.
Good luck...
geo - n4ua
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Hi William, You may have to sacrifice the pot by carefully sawing the shaft off, then the frozen knob can possibly be worked on in a more accessible location to prevent risk of front panel damage. Worst case may be to break the knob up (sacrilege) then dremel the brass insert away¡ ? Then the pot can be changed as described by a previous post and a new allen screw fitted to the knob. ? HIH Regards Nigel ?
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From: [email protected] <[email protected]> On Behalf Of k6whp
Sent: Tuesday, November 14, 2023 7:34 AM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob? Did that with no success.?
Thanks.?
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse." ?
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Re: HP 5315A With Destroyed Gate Pot and "frozen" Frozen Knob
Did that with no success.? Thanks.? -- William, k6whp -------------------- "Cheer up, things could get worse. So I cheered up and things got worse."
?
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Re: Cheap and simple OXCOs upgrades on ebay
As Matt says, I shouldn¡¯t engage, but that rarely stops me. ?This is one of those uncommon arguments where everybody has at least one good point.? ?? The original TimePod 5330A was introduced in 2011 at a price of US $3999, with the explicit goal of expanding the market for PN and stability measurement beyond the national labs and larger institutions that it was traditionally limited to.? At the time, the lowest-priced competition was about six times higher, and the market was relatively small.? I¡¯ve never heard any solid figures (and couldn¡¯t say anything too specific if I had), but I think Symmetricom was probably selling 50 to 100 of the TSC 5120As per year. ? Fast-forward a dozen years, and the 53100A is now priced at a level similar to the original competitors for the 5330A.? So in that sense, my goal of expanding the market to small R&D firms and serious hobbyists has not been entirely successful.? I¡¯m actually pretty psyched to see gadgets like Erik¡¯s tinyPFA finally come out after all this time.? They are scratching an itch that I ultimately couldn¡¯t reach.? Ditto for some of the more advanced open-source efforts like Andrew Holme¡¯s, which I¡¯ve pointed quite a few people towards. ? In the 53100A¡¯s defense, each one passes through many hands between the factory¡¯s stockroom and the end user¡¯s workbench.? Each pair of hands adds some value and captures some as well.? Then there¡¯s marketing, which everybody loves to diss until they find out what happens when you don¡¯t do it.? These were key reasons why the original TSC boxes were so expensive -- reasons I didn¡¯t fully appreciate when I was the Young Turk complaining about how somebody needed to Disrupt The Market?.? The market is still a relatively small one regardless of price, which means that those HP-like margins that none of us like to pay are unfortunately required to make the business worthwhile at all.? At least that¡¯s what I hear from the folks in the suits. ? Anyway, thanks for the very kind words of support from those who have chimed in.? The rest of you aren¡¯t wrong, any more than I was when I had the exact same attitude towards the existing players.? So, quit complaining, fire up your favorite CAD program, and start hacking. ? ? -- john, KE5FX Miles Design LLC 3120A/5330A/53100A dev ? ?
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From: [email protected] < [email protected]> On Behalf Of Roger Costello Sent: Friday, November 10, 2023 2:00 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] Cheap and simple OXCOs upgrades on ebay ? Hello Roy,
apologies for a lack of clarity on my part. Before John Miles designed the PhaseStation 53100A he produced the 5330A TimePod, ?later marketed by Microsemi which was an excellent performance, but significantly less evolved version. Think the cost of a smaller car vs a full size one. It does everything I need, so the excruciating expense of upgrading is not on my horizon. Mine was an early production version test unit assembled by him and has been flawless. For 3 way hat measurements, I am able to get similar results to the 53100A but am limited to around 30MHz maximum. The same TimeLab software is used, but internal references were not an option on the 5330A.?
I do also have 6 of the 'cheap and simple OXCOs upgrades from eBay' 3 of which I have used as internal 10MHz clock upgrades for various instruments that are needed to operate in the field without a GPS referenced clock. They considerably exceed the performance of the older HP 10811's they are replacing.
Regards,
Roger (VK6HZ)
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Michael A. Terrell
k6whp