Re: [time-nuts] Fan for old HP synthesizer
Magnus Danielson wrote: > From: "Poul-Henning Kamp" <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nuts > Digest, Vol 21, Issue 20) > Date: Tue, 18 Apr 2006 21:43:18 +0200 > Message-ID: <[EMAIL PROTECTED]> > >>In message <[EMAIL PROTECTED]>, "Christopher Hoover" writes: >> >> >>>As someone else mentioned, the form factor is often quasi-standard. Poring >>>over the Digi-Key catalog may be your best bet. >>> >>> Mtg Hole Ctr Sp - English : 3.25 in >>> Thkns - English : 1.5 in >> >>This is what's called a 92mm x 92mm x 38mm fan these days. >> >>There are many 92x92x25 mm fans available, you may be able to >>substitute one of these if 92x92x38 is impossible to find. > > > When checking the EBM-Papst site (http://www.ebmpapst.us) the 92x92x25 mm > fans did not > reach the same CFM, but those that I found (3212JN and 3214JN) was not doing > 117 VAC > (they where doing 12 VDC and 24 VDC respectively). While Papst isn't all > there is to fans > they are usually a good benchmark on what is available. You have to be careful with cfm ratings on fans. For small fans like this, the cfm rating will be in free air - i.e. no restrictions near by. For some larger fans, which must not be operating in free air, then this is obviously not so. As soon as you restrict the flow by putting obstructions in the path of the airflow, so the flow rate drops. At a particular back pressure, the flow drop becomes zero. The actual shape of the flow vs pressure curve, which you see in fan data sheets, can be changed by the design of the fan blades. I had an email from one of the fan manufacturers some time back when I was trying to replace a really odd sized fan in my Sun Ultra 80. (Sun's answer is to buy a new DC-DC converter with the fan on it, which was not too attractive.) Anyway, the fan manufacturer said that if a fan is designed for a particular customer, then it is quite common to optimise the fan blade design for there particular application. If the old fan is still working, and you can measure the air inlet and outlet temperatures, then find the difference between them. If the new fan results in a smaller difference between air input and air output temperatures, then the flow is greater so all is well. Obviously if this is in a cabinet with multiple fans, it is best to measure the difference only over the region being cooled by this fan. HP kit is usually well over-engineered, but you need to be careful as you are at high altitude, where the air is thinner and so less effective at cooling. Your safety margin will be smaller than for someone at sea level. dave ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Fan for old HP synthesizer
I have 3 HP synthesizers with what looks like the same fan: 8672, 8673 and 8656, and they are all very loud, the worse being the 8656. On top of that, the 8656 fan still runs when the unit is in standby. I have thought many times that I wanted to replace it with a 12V model so that I could wire it to the switched 12V inside the unit so that it would run only when the unit is operating and not in standby, but that particular synthesizer draws a lot of power in standby, and I am affraid that it really needs cooling even then... So, for now, I turn it off completely between uses and until I have my GPS locked frequency reference, I sync it to the timebase in the 8673 when I need to. I just got a 5 MHz ovenized crystal stabilized reference off eBay today, and I have a Jupiter receiver, so I am just some soldering away from a good frequency standard... Didier KO4BB Magnus Danielson wrote: >When checking the EBM-Papst site (http://www.ebmpapst.us) the 92x92x25 mm fans >did not >reach the same CFM, but those that I found (3212JN and 3214JN) was not doing >117 VAC >(they where doing 12 VDC and 24 VDC respectively). While Papst isn't all there >is to fans >they are usually a good benchmark on what is available. > >Come to think of it... I have a bunch of big nice Papst 9950 lying around ;O) >A little bigger (119x119) and eating 230 VAC but good for CFM 68,9 so almost >fit. ;O) > >Cheers, >Magnus > > > ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] tracor 308a rubidium oscillator needs mag field to come up to 5 MHz
i repaired the power supply in the tracor 308a that i acquired. a tant cap had shorted and blew out the rest of the main power circuit. btw, i used a trick to fix this power supply that i've used several times very successfully with other gear. it may be of interest to others. most of the supplies in older equipment are comprised of a pass transistor and a regulator section. the regulator section is typically either a regulator ic (e.g. lm[123]11) or an op amp ic with a reference. the pass transistor is usually in a to-3 case and mounted on a heat sink, often on the rear. the trick is to replace the pass transistor with an lt1038, a high current three-terminal positive regulator, and to rip out most of the regulator section, keeping/adding as need only a trim pot and appropriate bypass caps. the lt1038 in to-3 with proper sinking gives you 10 A current (peak to 24A) and up to 35V input-ouput differential. this often exceeds the abs max ratings of the older pnp power in the power circuit. back to the tracor 308a it lights up now and locks. it takes a while, but it stays that way. i've started taking some long t.i. runs to check the stability. early unscrutinized results indicate an adev of 5.6e-9 at tau=1s and 1.4e-9 at tau=10s. one issue remains: i have to crank the magnetic field setting almost to its high limit (9.91/10.00) to get 5 MHz out; lower settings give a frequency that is too low. i presume this is unusual. i have a rudimentary understanding of the rubidium oscillator physics, but i do not understand what would cause this. can i buy a clue? cheers, -- chritopher. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Fan for old HP synthesizer
From: "Poul-Henning Kamp" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nuts Digest, Vol 21, Issue 20) Date: Tue, 18 Apr 2006 21:43:18 +0200 Message-ID: <[EMAIL PROTECTED]> > In message <[EMAIL PROTECTED]>, "Christopher Hoover" writes: > > >As someone else mentioned, the form factor is often quasi-standard. Poring > >over the Digi-Key catalog may be your best bet. > > > > Mtg Hole Ctr Sp - English : 3.25 in > > Thkns - English : 1.5 in > > This is what's called a 92mm x 92mm x 38mm fan these days. > > There are many 92x92x25 mm fans available, you may be able to > substitute one of these if 92x92x38 is impossible to find. When checking the EBM-Papst site (http://www.ebmpapst.us) the 92x92x25 mm fans did not reach the same CFM, but those that I found (3212JN and 3214JN) was not doing 117 VAC (they where doing 12 VDC and 24 VDC respectively). While Papst isn't all there is to fans they are usually a good benchmark on what is available. Come to think of it... I have a bunch of big nice Papst 9950 lying around ;O) A little bigger (119x119) and eating 230 VAC but good for CFM 68,9 so almost fit. ;O) Cheers, Magnus ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nutsDigest, Vol 21, Issue 20)
I'd say that the biggest concern after physical size and Voltage requirements is that it has an adequate CFM rating. That's THE most important. Daun -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Poul-Henning Kamp Sent: Tuesday, April 18, 2006 3:43 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nutsDigest, Vol 21, Issue 20) In message <[EMAIL PROTECTED]>, "Christopher Hoover" writes: >As someone else mentioned, the form factor is often quasi-standard. >Poring over the Digi-Key catalog may be your best bet. > > Mtg Hole Ctr Sp - English : 3.25 in > Thkns - English : 1.5 in This is what's called a 92mm x 92mm x 38mm fan these days. There are many 92x92x25 mm fans available, you may be able to substitute one of these if 92x92x38 is impossible to find. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nuts Digest, Vol 21, Issue 20)
In message <[EMAIL PROTECTED]>, "Christopher Hoover" writes: >As someone else mentioned, the form factor is often quasi-standard. Poring >over the Digi-Key catalog may be your best bet. > > Mtg Hole Ctr Sp - English : 3.25 in > Thkns - English : 1.5 in This is what's called a 92mm x 92mm x 38mm fan these days. There are many 92x92x25 mm fans available, you may be able to substitute one of these if 92x92x38 is impossible to find. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Fan for old HP synthesizer (was RE: time-nuts Digest, Vol 21, Issue 20)
David Forbes wrote: > The fan model is SWS2107FL-51, HP part number 3160-0296. David, Here is the info on that 4x4 p/n. If you can't find a direct replacement from one of the original suppliers, perhaps the specifications will help you zero in on a suitable replacement. As someone else mentioned, the form factor is often quasi-standard. Poring over the Digi-Key catalog may be your best bet. Cheers, -- Christopher. mailto:ch(at)murgatroid(dot)com HP Part Number : 3160-0296 FUNCTIONAL/PHYSICAL INFORMATION: Type : N/A Classification: FAN-SKELETON V Rtd : 115 VAC Ln Freq : 50/60 Hz Inp Cur - Nom : UNK A Inp Pwr - Nom : UNK W Air Flow - Min: N/S CFM Air Flow - Nom: 72 CFM Air Flow - Max: N/S CFM RPM - Nom : UNK Noise : UNK dB Brng Tp : SLEEVE BEARING Hsg/Bld Matl : ZINC/PLASTIC Termn Tp : UNK Wr Ld Lg - English: UNK in Termn Conn Mpn: UNK Conn Cntct Mpn: UNK Mtg Hole Dia English : UNK in Mtg Hole Ctr Sp - English : 3.25 in Lg - English : UNK in Wd - English : UNK in Thkns - English : 1.5 in Mtg Hole Dia - Metric : UNK m Mtg Hole Ctr Sp - Metric : N/S m Lg - Metric : UNK m Wd - Metric : UNK m Thkns - Metric: N/S m Additional Information: UNK HP PART SUPPLIER INFORMATION: A) Name : IMC MAGNETICS CORP Name Abbreviation : IMC City : MINEOLA Geographic Area Name : NY Country Code : US Manufacturer Part Number : SWS2107FL-51 B) Name : N M B TECHNOLOGIES INC Name Abbreviation : NMBT City : CHATSWORTH Geographic Area Name : CA Country Code : US Manufacturer Part Number : SWS2107FL-51 ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
