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Re: HP 3852A firmware update issue

 

You can of course put a 32k blob, in the upper half of a 27x512, and it will work.? Put the same blob in both halves of a 64k EPROM and you're golden.

Done all that soooo many times with other kit that had firmware in 32k images, but only 64k chips being available.

73.

Dave 'KBV.
Re: Is it worth looking for a R/3*2 Instrument Controller? - Feedback request

 

What I seem to recall mainly involved the handshaking between the controller and instruments. The Motorola CPU¡¯s, PA-RISC CPU¡¯s architecture did the I/O and handshaking very well. Another issue was multitasking. The Intel CPU¡¯s (at that time) did not seem to do the I/O and handshaking nearly as well, and did not seem to multitask. The programs we tried to run on Intel CPU¡¯s back in the 80¡¯s would sporadically lock up, report timing issues, garble data. The HP 9000/300, 9000/700 series ran our software seamlessly. While working at HP on an on-site cal team we ran between 12 to 16 calibration procedures (via separate windows for each cal procedure) simultaneously on a 9000 system comprised of 1 ea. /750 server and 3 ea. /382¡¯s workstations each with 4 GPIB busses, we could also add an additional 9000/382 if it was needed for the particular job/campaign. The control system was not slow and never bogged down. I do know that the older C110 workstations are still in use as the older HPUX/Basic calibration software has not been ported over to PC based workstations as yet.

Don Bitters
Re: 3457A carbon composite resistors in signal path?

 

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a lot of times carbon comps were used as they could handle surge I better and not go open
¸é±ð²Ô¨¦±ð

On 5/7/24 6:08 PM, Richard Knoppow via groups.io wrote:

?? composition resistors actually have more spurious reactance than film resistors. I have no idea why these were used but suspect carbon or metal film resistors would work at least as well.

On 5/7/2024 5:36 PM, Jared Cabot via groups.io wrote:
I recently performed a few repairs on a friends 3457A multimeter (new RAM battery, replacement current range switching relays and added thermal insulation on the LM339 vreg) and have also just acquired one of my own that I'll do the RAM battery replacement, LM339 thermal insulation and maybe power supply capacitor replacement on.

I noticed there are a number of 51K carbon composition resistors in the signal path, which I found a bit strange...
You can see them in the input switching section highlighted in yellow of the linked image below, R101, R102, R201, R202, R203, R204


As carbon composition resistors are prone to drift and noise with age, would it be of any benefit to replace these with metal film resistors? Or is there some reason carbon composite were used here (high pulse energy handling and low inductance etc)?



Thanks!
Jared



Re: Parts needed

 

In the interim while you look around for the correct connector socket, you might try putting epoxy in the broken ends and put a zip tie around the connector. I used this method for a couple of years until I found my correct connector.

Don Bitters
Re: 3457A carbon composite resistors in signal path?

 

composition resistors actually have more spurious reactance than film resistors. I have no idea why these were used but suspect carbon or metal film resistors would work at least as well.

On 5/7/2024 5:36 PM, Jared Cabot via groups.io wrote:
I recently performed a few repairs on a friends 3457A multimeter (new RAM battery, replacement current range switching relays and added thermal insulation on the LM339 vreg) and have also just acquired one of my own that I'll do the RAM battery replacement, LM339 thermal insulation and maybe power supply capacitor replacement on.
I noticed there are a number of 51K carbon composition resistors in the signal path, which I found a bit strange...
You can see them in the input switching section highlighted in yellow of the linked image below, R101, R102, R201, R202, R203, R204
<>
As carbon composition resistors are prone to drift and noise with age, would it be of any benefit to replace these with metal film resistors? Or is there some reason carbon composite were used here (high pulse energy handling and low inductance etc)?
Thanks!
Jared
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
Re: Cheap and simple OXCOs upgrades on ebay

 

Amazing quality for so little money!?
My CTI board would not adjust to 10Mhz (also compared against leo bodnar referenced FA-3 counter).?
LT1009 2.5V reference on the board just could not make the grade to get it up to frequency,? (data sheet for the cti spec is +- 2 v around 2.5V).?
2.490 as supplied from Lt1009 just would not get it there. So LT1009 datasheet has an adj pin 5 (i think) so i shorted output 6 to adj 5 and I get now 2.7V which is perfect for correct frequency range adjustment.?
Just thought this might be of use to anyone who cant get the full 10Mhz by the supplied reference voltage.
some mods exist on the net to remove R1 and short another resistor. All these got closer but no cigar!

maxwelloau VK5AC.
3457A carbon composite resistors in signal path?

 

I recently performed a few repairs on a friends 3457A multimeter (new RAM battery, replacement current range switching relays and added thermal insulation on the LM339 vreg) and have also just acquired one of my own that I'll do the RAM battery replacement, LM339 thermal insulation and maybe power supply capacitor replacement on.

I noticed there are a number of 51K carbon composition resistors in the signal path, which I found a bit strange...
You can see them in the input switching section highlighted in yellow of the linked image below, R101, R102, R201, R202, R203, R204


As carbon composition resistors are prone to drift and noise with age, would it be of any benefit to replace these with metal film resistors? Or is there some reason carbon composite were used here (high pulse energy handling and low inductance etc)?



Thanks!
Jared
Re: Cheap and simple OXCOs upgrades on ebay

 

I having been having fun with mine.
Not the same ambience as a 5370¡¯s fan blasting away.
Documentation is somewhat cryptic.
Runs nice with Timelab.
Only hint is get the levels right for best performance.
Data looks good so far.
Noise floor is fantastic.

Dave
VE7HR

On May 7, 2024, at 4:56?PM, Dave McGuire via groups.io <mcguire@...> wrote:

?On 5/7/24 19:52, Ed (scskits) wrote:
Just got in a TinyPFA.
Hopefully I can get some more data on the GPSDO and other OCXOs that I have.
Any setups for the TinyPFA that can help with the learning curve would be appreciated.
I just got one as well, haven't even opened the box yet. I'm interested to hear about your activities.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Cheap and simple OXCOs upgrades on ebay

 

On 5/7/24 19:52, Ed (scskits) wrote:
Just got in a TinyPFA.
Hopefully I can get some more data on the GPSDO and other OCXOs that I have.
Any setups for the TinyPFA that can help with the learning curve would be appreciated.
I just got one as well, haven't even opened the box yet. I'm interested to hear about your activities.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: Cheap and simple OXCOs upgrades on ebay

 

Just got in a TinyPFA.

Hopefully I can get some more data on the GPSDO and other OCXOs that I have.

Any setups for the TinyPFA that can help with the learning curve would be appreciated.

ed
Re: HP 8405A Vector Voltmeter Probes

 

I'm at the stage now where I'm going to need to improve the test setup. This means using a sig gen with lower harmonic distortion and also using external levelling using a thermocouple power meter. The external levelling also improves the source match because I use an 11667A splitter in the external levelling system.

I will also have to factor in the response of my homebrew 'tee'. This replaces the official HP 11536A tee. I designed it many years ago using SMA connectors and it includes compensation for the 2.5pF input capacitance of the 8405A probe. I'm fairly certain there will be something similar inside the 11536A although I've never take one apart. The compensation improves the input VSWR when the probe is attached. I get similar VSWR vs frequency as the 11536A up to about 700MHz. With the 8405A probe attached, my homebrew tee manages a VSWR < 1.03:1 below 500MHz but it degrades to about 1.1:1 by 700MHz. Sadly, I can't match the VSWR or amplitude performance of the 11536A above 700MHz. There will be some extra compensation somewhere that I haven't got in my homebrew version. All I can hope to do here is try and get the same frequency response as the healthy A probe above 700MHz.

The simulation of my homebrew tee does show an upwards slope of about 0.1dB by 500MHz when a 1 port VNA model of the 8405A probe? is connected to the tee connection. So some of the slope I'm seeing will be in the tee. I suspect that the 11536A will be similar or maybe slightly better.

These upgrades in the test setup are needed because I'm hoping for yet more improvement when I try the BAT-62 diodes. There's a chance they will be here tomorrow, but they will probably arrive later in the week. I need to be able to measure the flatness to a few percent up into VHF and UHF so I need a very accurate signal source with very low source VSWR.
Re: HP 8405A Vector Voltmeter Probes

 

Thanks. I'm not sure what device will be most vulnerable when connecting the probe tip to +/- 50V DC. There will be a large transient generated via the 150pF input blocking capacitor and it might damage the PN junction of the P JFET. It might be able to damage the diodes but the transient will be quite narrow and Schottky diodes can avalanche for long periods without failure as long as the current is limited. So I'm willing to take the risk if i can get the performance from >= 15V rated diodes.

I had a rummage through my stash of Schottky diodes and managed to find some of the NXP 1PS70 82 diodes.

I fitted these to the B probe and also refitted the 8405A diode to it. I re-tested it up to 300MHz and it was much improved compared to the 1N6263 diodes.

There was a gradual slope with increasing frequency that raised the level about +0.25dB by 200MHz and +0.4dB by 300MHz. This compares to +2dB by 250MHz with the 1N6263 diodes.?

The datasheet for the NXP diode does show the capacitance is a little bit higher than my measurement of the the 8405A diodes (both at 3V reverse bias) so maybe this explains the fact that these diodes are still not giving quite the same frequency response as the originals. It's much closer, but still not right.
HP3336 troubleshooting

 

Did HP ever produce the troubleshooting guide for the 3336A/B/C that was promised in the service manual dated October 1979?
--
Joe White
KW4YW
Re: HP 3852A firmware update issue

 

On 5/7/24 16:06, gren wrote:
Just uploaded a file folder with the Hp3852a v4.22 Rom set in Intel Hex Format.
I've downloaded and deleted these. As mentioned in my other message, as soon as we straighten out the file size disparity I will zip and re-upload them. I've also created a subdirectory for the 3852A firmware upgrade files and documentation, and concatenated the two-part PDF that you uploaded earlier and re-uploaded that.

Something funny about the Signature recognition of the Rom's, > ? The Hp Rom's were not protected in any way,
These are standard byte-wide EPROMs. No copy protection is possible, or has ever been possible, with these components.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: HP 3852A firmware update issue

 

Signature modes, etc are all "standard EPROM stuff" and is really muddying the waters here. Any reasonable device programmer will handle all of this automatically, i.e. when you select a specific manufacturer's 27512 part it will verify the signature using that manufacturer's signature access algorithm.

This is nothing new, is all well-documented, standard, and common.

-Dave

On 5/7/24 16:11, gren wrote:
... old notes:
"
Look at the data sheets for the 27C256 from TI, ST, and AMD.
They ALL call for the same procedure (almost) getting into signature mode,
Take the A9 address line and drive it to 12VDC while all others except A0 are taken
to ?logic zero.
When A0 = 0, you get the manufacturer¡¯s code
When A0 = 1, you get the device code.
My point was, that A9 was NEVER taken above 5VDC. So if signature mode IS STILL the TRICK,
They must be using some UNDOCUMENTED way to get there. (maybe the EPROM were custom made for HP using some strange protocol to get into signature mode)
The U57 & U58 that I have looked at do not appear to have any strange markings or part numbers, they look like genuine AMD parts!
They have also used ¡°one time programmable¡± ROMs made by TI, and they don¡¯t appear to have any strange part numbers on them.
I need to go after this with a logic analyzer, (I have one) but it will be a brutally time consuming task (especially since I am not a 68000 expert)
It will be nice to actually watch as 91H is loaded on the data bus while placing the EPROMs in signature mode.
--
Dave McGuire, AK4HZ
New Kensington, PA
File Notifications #file-notice

Group Notification
 

The following files and folders have been uploaded to the Files area of the [email protected] group.

By: Dave McGuire <mcguire@...>

Description:
3852A ROM upgrade document, 9/89

The following files and folders have been uploaded to the Files area of the [email protected] group.

By: Dave McGuire <mcguire@...>

Description:
3852A ROM upgrade document, 2/91
Re: HP 3852A firmware update issue

 

On 5/7/24 17:03, Dave McGuire wrote:
On 5/7/24 16:57, Maciej Kawalkowski wrote:
??? 2.? ALL EPROMS are 27C256 *EXCEPT *?for U57 & U58 which are 27C512.

This confirms my findings. The issue is the posted version B4.22 was made with all images being 32k but U57 and U58 need 64k images.
? Waitaminute.? The files Rick just uploaded (which I am in the process of cleaning up and repackaging) are all 32KB images.? What's up with this?
FYI, I've deleted those files but I have them here, I'll re-upload them as a zip file when we straighten this out. A 27512 is a 64KB device!

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: HP 3852A firmware update issue

 

On 5/7/24 16:57, Maciej Kawalkowski wrote:
2.? ALL EPROMS are 27C256 *EXCEPT *?for U57 & U58 which are 27C512.
This confirms my findings. The issue is the posted version B4.22 was made with all images being 32k but U57 and U58 need 64k images.
Waitaminute. The files Rick just uploaded (which I am in the process of cleaning up and repackaging) are all 32KB images. What's up with this?

ra$ ls -lh
total 649K
-rw-r--r-- 1 mcguire mcguire 142 May 7 17:00 files.txt
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U57_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U58_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U59_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U60_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U61_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U62_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U90_Rev422.hex
-rw-rw-r-- 1 mcguire mcguire 78K May 7 16:57 U91_Rev422.hex
ra$ srec_info U57_Rev422.hex -intel
Format: Intel Hexadecimal (MCS-86)
Data: 0000 - 7FFF
ra$

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
Re: HP 3852A firmware update issue

 

On Tue, May 7, 2024 at 04:28 PM, gren wrote:

.? ALL EPROMS are 27C256? EXCEPT ??for U57 & U58 which are 27C512.

?

This confirms my findings. The issue is that the V4.22 Rom images are all 32k to fit into 27c256 but U57 and U58 need to be 64k.?
V4.21 are all 64k.?
Re: HP 3852A firmware update issue

 

On 5/7/24 16:22, gren wrote:
Just uploaded the Hp 3852a ROM kit Part 1 instructions ( 9MB )
-- these might be for v4.00 ROMs, but may provide clues.
Hi Rick, this appears to be the same document, though an earlier revision, that has been floating around for a long time. Why is it split into two parts?

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
7361 - 7380 of 151078