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Re: HP 3852A firmware update issue
You missed this from my message yesterday: - All of the EPROMs in the 4.21 image set are 64KB. - All of the EPROMs in the 4.22 set are 32KB. -Dave -- Dave McGuire, AK4HZ New
By Dave McGuire · #144207 ·
Re: HP 3852A firmware update issue
If it is known that V4.22 has a mix of 256's and 512's, and they are being replaced by all 512's (some doubled), then I think a non zebra answer is evident. -Chuck
By Chuck Harris · #144206 ·
Re: HP 3852A firmware update issue
Hi Dave, It always amazes me the impossibly simple mistakes I will make. I assume it is similar for others. -Chuck Harris <mcguire@...> wrote:
By Chuck Harris · #144205 ·
Re: HP 130A restoration
Many digital capacitor meters use a method championed in the 1970's by Sencore with their "Z-Meters", which is to measure capacitance by timing how long it takes for the capacitor to charge, and to
By Chuck Harris · #144204 ·
Re: 3457A carbon composite resistors in signal path?
Well, I lifted one leg of each resistor, let them cool to ambient and measured the resistance. Here's what I got. (They are 5% resistors). 55.20K - 7.91% 54.41K - 6.51% 56.15K - 9.61% 53.67K -
By Jared Cabot · #144203 ·
OT / WTB: Travelling wave tubes
Years ago I picked up a HP 491C TWT amplifier that does 2 - 4 GHz at about 1W for nearly nothing at auction. Unfortunately the tube was toast and it's now sitting on the shelf. These tubes have
By M_A_C <s2007579@...> · #144202 ·
Re: HP 3852A firmware update issue
It is entirely possible though. I will need to open up my unit to see as it was such a long time ago.
By Anders · #144201 ·
Re: HP 8566B PL2 unlock error
The service manuals are excellent in diagnosing problems like this.I would highly recommend the RF section manual - RF tune section block diagram, the theory of operation, then focus on the PLL lock
By Don Bitters · #144200 ·
Re: 3457A carbon composite resistors in signal path?
The resistors are in a high impedance part of the circuit so the absolute value will not affect the accuracy of the readings. As others have said, part of the input protection and probably chosen for
By Robert G8RPI · #144199 ·
Re: HP 8566B PL2 unlock error
When I repaired my 8645A some years ago I noticed a very sluggish user interface whenever the PLL unlocked. I guess repeated unlock signals did continuously interrupt the CPU to produce that effect.
By Martin · #144198 ·
Re: HP 130A restoration
Thank you all, very useful. Factory, I will replace all power supply paper capacitors, and thanks about checking that the values didn't change for all serial numbers. The cap values should be to a
By Bepi · #144197 ·
Re: 8657B Signal Generator Noise with RF Off
Dear Yves, Thank you for the comparative measurement, showing noise from the 8657B in RF Off being 4.6 dB above thermal noise. The difference I measured is somewhat less, because I did not correct
By alwyn.seeds1 · #144196 ·
Re: Agt N5230A-220 Need help
Hello All, Thanks for your help! We finally solved the problem which was caused by the OS which was corrupted. Br. Antoine
By Electro4lease · #144195 ·
Re: HP 3852A firmware update issue
Btw I did get hold of Julio and he confirmed that there is a mix of 27C512 and 27C256 chips on the 4.22 ROM. Unfortunately he cannot read the EPROMs from the unit as he no longer has any windows PC to
By Maciej Kawalkowski · #144194 ·
Re: HP 3852A firmware update issue
Maybe some else wants to install the 4.22 roms and check ?
By Maciej Kawalkowski · #144193 ·
Re: HP 3852A firmware update issue
I don't think I'm misidentifying the hoofbeats as zebras. I'm perfectly willing to admit that I may have missed something, and I really hope that I have, because that means there's really no
By Dave McGuire · #144192 ·
Re: 3457A carbon composite resistors in signal path?
The carbon composition resistors were probably used with the thought that they are rugged, and will only introduce a variation that is less than system noise. However, carbon composition resistors
By Chuck Harris · #144191 ·
Re: HP 3852A firmware update issue
Hi Dave, I can't help it, when you say stuff that sounds like you are missing something simple, I am going to try to help you as politely as I can. We all make incorrect assumptions, and we
By Chuck Harris · #144190 ·
Re: Cheap and simple OXCOs upgrades on ebay
Well damn, now I'm really looking forward to it. I wish I wasn't so damn busy this week. I'm shipping prototypes of a new design to an absolutely neurotic client next week. :-/
By Dave McGuire · #144189 ·
Re: 3457A carbon composite resistors in signal path?
Jared, A couple of points: - Please make sure you account for your 731B's own tempco, which typically is not negligible. I have one that's unusually stable, but most units exhibit quite a
By Radu Bogdan Dicher · #144188 ·