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Hamfest find today: HP59309A Clock
08-08-2016, 04:29 AM
Post: #1
Hamfest find today: HP59309A Clock
I was attending a hamfest today ("radio rally" in the UK; "rubbish redistribution" to non-hams) and was surprised to spot this lonely little guy.

Try as I might, I couldn't just leave it there :-)

Bob


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08-08-2016, 12:47 PM (This post was last modified: 09-18-2018 03:56 PM by Accutron.)
Post: #2
RE: Hamfest find today: HP59309A Clock
Nice find. I miss the good old days when you could get huge piles of surplus HP test equipment for really low prices. Ever since the 2008 financial crisis, it seems like the pickings have gotten really slim, and everybody wants top dollar. The gold scrappers hit it pretty hard in 2008-2010, and then the vendors figured it out and started jacking up the prices to keep it from getting scrapped.

I did have a pretty good HP find at Hamvention this year though - a mint condition HP 9000/300 Model 310, with a 9133 combo disk drive, monitor keyboard, cables, software and manuals for $100. I also picked up two 37201A HP-IB extenders from the same guy for $10 each. I found it on Friday morning right before they opened the gates. The first HP guy that walked by would've snapped it up. Luckily that happened to be me.

[Image: hp9000.jpg]
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08-08-2016, 04:06 PM
Post: #3
RE: Hamfest find today: HP59309A Clock
(08-08-2016 04:29 AM)BobVA Wrote:  I was attending a hamfest today ("radio rally" in the UK; "rubbish redistribution" to non-hams) and was surprised to spot this lonely little guy.

Try as I might, I couldn't just leave it there :-)

Bob

They are a nice clock, it looks like it is in good condition. I have two, one is running on the 10MHz from a GPSDO. It is the clock at my work desk and I also use it to set the time on some of my old HP systems. I wrote a program to set and read the time using a 86B and later modified the programs for Workstation BASIC on a 9000 and also for my 9835.
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08-09-2016, 12:25 AM
Post: #4
RE: Hamfest find today: HP59309A Clock
Nice find Bob,
I never knew they had a unit like that, I will have to start looking now.
I was lucky to go to a vintage electronics expo in Michigan USA in July, and came out with some nice LED calculators including a hard to find SCAT conversion calculator and a LED Mickey mouse calculator, all in one event. ( I was hoping to find HP 01)You never know what you find when you least expect it.
Ray
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08-09-2016, 03:17 AM (This post was last modified: 08-09-2016 07:41 PM by BobVA.)
Post: #5
RE: Hamfest find today: HP59309A Clock
(08-08-2016 04:06 PM)Paul Berger (Canada) Wrote:  They are a nice clock, it looks like it is in good condition. I have two, one is running on the 10MHz from a GPSDO.

Cool! What's the base oscillator? Quartz? I've got a 10 MHz Rb oscillator, but I think I'd have to get a second job to pay my electric bill if I kept that space heater running 24/7.

I ordered a 2.5ppm 10MHz TCXO from a surplus seller. It's in a pretty small (SMD package) so I was thinking of replacing the stock quartz oscillator with it to increase the accuracy.

Unfortunately I don't have any HP-IB gear, so I can only fiddle with the front panel.

Ray Wrote:Nice find Bob,
I never knew they had a unit like that, I will have to start looking now.

Thanks! I'd had a search running on the auction sites, but the price was pretty high when they'd turn up. I think they must still be in use in some installations, keeping the prices up.

Accutron Wrote:I did have a pretty good HP find at Hamvention this year though - a mint condition HP 9000/300 Model 310, with a 9133 combo disk drive, monitor keyboard, cables, software and manuals for $100.

I'll say you did!
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08-09-2016, 03:52 AM
Post: #6
RE: Hamfest find today: HP59309A Clock
(08-09-2016 03:17 AM)BobVA Wrote:  I think they must still be in use in some installations, keeping the prices up.

It could just be the clock collectors running the prices up. The Nixie clock guys go after HP clocks and cesium standards as well. The 59309A also uses the 5-digit HP bubble displays, which are desirable on their own. I'm always on the lookout for HP equipment with older style LED displays - epoxy-packed bubble displays, early single-digit decimal/hex and alphanumeric smart displays, and anything packed in glass and ceramic.
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08-09-2016, 12:23 PM
Post: #7
RE: Hamfest find today: HP59309A Clock
(08-09-2016 03:17 AM)BobVA Wrote:  
(08-08-2016 04:06 PM)Paul Berger (Canada) Wrote:  They are a nice clock, it looks like it is in good condition. I have two, one is running on the 10MHz from a GPSDO.

Cool! What's the base oscillator? Quartz? I've got a 10 MHz Rb oscillator, but I think I'd have to get a second job to pay my electric bill if I kept that space heater running 24/7.

I ordered a 2.5ppm 10MHz TXCO from a surplus seller. It's in a pretty small (SMD package) so I was thinking of replacing the stock quartz oscillator with it to increase the accuracy.

Unfortunately I don't have any HP-IB gear, so I can only fiddle with the front panel.

The base oscillator is a quartz OXCO, this is the most common type of GPSDO, there is such a thing as Rb based GPSDOs but they are far less common. I have a couple Rb oscillators as well but don't use them a lot.

I hope you don't have many power outages, I think setting date and time from the front panel would get old. You can connect a 9V battery internally but I am not sure how long that would last. I had one of mine connected to a pack of 6 C cells for backup power. There is a BNC connector on the back for external backup power. When using the external connector there is a jumper on the base board near the 9V battery connector that needs to be in place.

You don't necessarily need HP GPIB equipment to talk to the clock, any kind of GPIB host will do, the GPIB interface is a pretty simple minded state machine controlled interface. Manuals for the HP 59309A are available online.



If you are interested in precision time keeping there is a mailing list "time-nuts" that has a lot of very knowledgeable subscribers and lots of information in its archives.

Paul.
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08-09-2016, 06:31 PM (This post was last modified: 08-09-2016 07:42 PM by BobVA.)
Post: #8
RE: Hamfest find today: HP59309A Clock
(08-09-2016 12:23 PM)Paul Berger (Canada) Wrote:  I hope you don't have many power outages, I think setting date and time from the front panel would get old. You can connect a 9V battery internally but I am not sure how long that would last. I had one of mine connected to a pack of 6 C cells for backup power. There is a BNC connector on the back for external backup power. When using the external connector there is a jumper on the base board near the 9V battery connector that needs to be in place.

Paul.

Thanks!

Surprisingly the deal included a copy of the manual, which was interesting reading. It specifies 24 hours of backup from an internal 9v battery. Another section of the manual quotes the current draw as 2 mA at the external power terminal.

There was apparently a complementary backup battery housing (K10-59992 Standby Power Supply), the same size as the 59309A, which used "D" batteries and would allow one year of backup operation - very similar to your backup.
If I did the math correctly a 9v lithium primary battery should be good for a week or so of backup.

It's drifted about five seconds in 36 hours, so I'll check the calibration soon. Hopefully the TCXO will be the longer term fix to that. I had incorrectly assumed the internal oscillator was 10 MHz, but a closer look at the manual shows it's 1 MHz, so the one I ordered will have to go through the external reference port. I'll have to look around for a 1 MHz model.
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08-14-2016, 03:35 AM (This post was last modified: 08-14-2016 03:43 AM by Adam Vaughn.)
Post: #9
RE: Hamfest find today: HP59309A Clock
Nice find! I've had a 59309A for several years; acquired it long before I had any idea HP had made calculators! Other than some occasional glitches, it's worked quite well over the years. I have noticed that it tends to drift forwards relative to other clocks I have (most of which are synchronized by the power line). I'm guessing there's some sort of internal adjustment for this (mine is running off of its internal oscillator), but have yet to build up the courage to attempt to tweak it...

As for external power, there is indeed an internal socket for a 9V battery, though HP put all sorts of warnings around it saying something like a leaking battery installed in it would void the warranty (big stuff for a $995 device in 1976!). I'm pretty sure a simple/effective external backup could be made using a battery holder for six D cells wired to a BNC connector (pretty sure center pin is positive, though I have yet to verify this for myself). Anyway, here's a picture of my 59309A:

[Image: hp59309a_small.jpg]

It's been modified with a toggle switch in place of the momentary display on/off button, though the previous owner kindly included the original switch as well as the cover for the button panel. I have yet to use it as a RTC source for any of my computers or calculators, though I may try it with my HP 85A if I can find a HPIB module for it. My biggest complaint about it is the use of the tiny calculator digits, though given the fact that the display was probably considered a secondary (tertiary?) function of the unit, it's understandable... Wink
-Adam
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08-15-2016, 01:16 AM (This post was last modified: 08-15-2016 01:37 AM by BobVA.)
Post: #10
RE: Hamfest find today: HP59309A Clock
(08-14-2016 03:35 AM)Adam Vaughn Wrote:  As for external power, there is indeed an internal socket for a 9V battery, though HP put all sorts of warnings around it saying something like a leaking battery installed in it would void the warranty (big stuff for a $995 device in 1976!). I'm pretty sure a simple/effective external backup could be made using a battery holder for six D cells wired to a BNC connector (pretty sure center pin is positive, though I have yet to verify this for myself). Anyway, here's a picture of my 59309A:

Thanks! Between being a clock, being made by HP and having LED's it's my perfect dust collector!

I actually tried to install a backup battery, but I don't think it's possible today. Modern 9v batteries seem to be too large to fit down through the aluminum bracket that's supposed to hold it in place and properly align with the connector on the motherboard. The back panel connector is probably the best bet.

I wonder if the previous owner of yours was running it solely off the backup power connector and not using the internal power supply? That would be a good reason to replace the push-to-read button with a toggle switch. (The display is always on if it's running off the internal line supply, so no need to push the button).
That's kind of an interesting idea though, for just using it as a desk clock (the HP-IB part won't work on backup power). Probably run much cooler, since it bypasses a lot of the linear power supply, particularly the toasty 5v regulator on the back panel.

I ordered a 0.25 ppm 10 MHz oscillator module so I'm hoping to put that and a backup supply in a small box to plug into the back panel. Fun toy!

Regards,
Bob
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08-15-2016, 04:06 AM (This post was last modified: 08-15-2016 04:07 AM by Adam Vaughn.)
Post: #11
RE: Hamfest find today: HP59309A Clock
Not sure that the size of 9V batteries has changed a whole lot since the '70s, but I could be wrong. With something as complicated as this, I'd want to use external batteries anyway, since it probably wouldn't take much battery leakage to mess up the boards. Granted, this was more true in the days of carbon-zinc batteries, but still.

I talked with the seller when I bought the clock, and he said that he wanted to be able to toggle the display on continuously rather than having to press the button every time he wanted to see it. From what I've heard, there's a switch or whatnot somewhere in the unit which indeed sets the display to light continuously, but I'm not sure if he knew about it. In any case, I tend to have the display turned off unless I'm standing near it. It didn't come with a backup supply, so I rather doubt that he used it with one.

Good luck on the frequency standard. I was hoping to be able to use my Heathkit GC-1000 "Most Accurate Clock" to keep the 59309A in-line, but the GC-1000's output is 3.6MHz (why??!?!?!?!), so it'd probably be more difficult than it's worth to convert it to 1, 5, or 10MHz. I also have yet to quantify exactly how much the 59309A's internal oscillator drifts; I have the service manual for it around here somewhere, but I'm not sure if it mentions calibration methods.
-Adam
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08-15-2016, 11:14 AM
Post: #12
RE: Hamfest find today: HP59309A Clock
(08-15-2016 04:06 AM)Adam Vaughn Wrote:  the GC-1000's output is 3.6MHz (why??!?!?!?!)

Because one tick equals exactly one ms which makes easy to count times in ms and s.
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08-15-2016, 08:10 PM
Post: #13
RE: Hamfest find today: HP59309A Clock
(08-15-2016 11:14 AM)damaltor Wrote:  
(08-15-2016 04:06 AM)Adam Vaughn Wrote:  the GC-1000's output is 3.6MHz (why??!?!?!?!)

Because one tick equals exactly one ms which makes easy to count times in ms and s.

That could very well be. I also know that 3.6MHz is the clock speed of the MOSTek MK3870 microcontroller, but wasn't sure why they picked it. It is truly an interesting device, with said 3.6MHz output being disciplined by its synchronizations with WWV. More info on this aspect can be found here.
-Adam
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