Aeroflex IFR-2398 / calibration / repair help

[andy_silicon]

Does anyone have the calibration software ?
Alternatively a dump of the firmware ?
Or possibly knowledge of the Gpib commands involved in the calibration procedure ?

I have an EBay score IFR-2398 which is mostly okay - except it fails the Level Cal.

Attenuator looks fine , 40Mhz cal signal shows at -41dBm ( should be -30 ).
From my good signal source it does look a little all over the place for level - so it may be that the level calibration is required ( looking at the service manual )

Any guidance / theories / previous experience appreciated.

I have access to a decent signal source ( Agilent E4437B ) , and a pretty accurate VSA (E4406A) , a few scopes and general test equipment to aid alignment/repair.

Note: I asked aeroflex - they are only interested in performing the calibration themselves. ( for about 450 quid )
I ask you - where's the fun in that !

Equipment porn by request ( it has hundreds of screws and is a pain to disassemble the RF section )

[andy_silicon]

Okay - so I guess I'm on my own.

Unit disassembled - cpu board removed.
Flash was socketed ( clamshell - psop device ). Cpu is intel i386ex embedded device.
Arggh - PA28F400B5T ....
Scrabble through the older adapters , and find an old WinLV programmer.
Woo hoo - flash dumped.

Now how do I find the config/system password.
Thrown the flash image into IDA , worked out that the base of the flash is 0x3f80000.
Ram starts at 0x0000000
Seems to be written around JMS C:Executive

Lots of features in the flash related to calibration but not easy to access from the unit - I guess the work begins now.

[andy_silicon]

Okay - the service manual mentions keying in the password "27329780" to get to the factory setting which allows the calibration tables to be cleared before recalibration.

For the life of me I couldn't get this password to work. ( no enter key! )

So after much reverse engineering I now see the bloody obvious.
( once you see that they used a generic routine for entering numbers it was obvious the termination of input was one of the Hz/Mhz/GHz buttons )

It's the "Hz" key to enter the password.

Sigh....

At least on the way I discovered another password for the system menu "72237908"

Needless to say don't mess with these extra menus unless you wan't to wipe out you calibration.


There do appear to be undocumented gpib commands - the work continues.

[andy_silicon]

It does look like you can perform the various calibrations from the front panel
( once you enable the factory menu with the password.

It's going to be tedious.

I think there must be a way to upload/download the calibration tables via gpib.
Not sure yet how to do that.

[videobruce]

Do you think that password would allow unlocking any options? I had a 2399A that I wished I never sold. The main reason was that damn floppy. 

Good luck on your project, I'm surprised no one stepped up to the plate yet.

[andy_silicon]

The password for the system menu may do that - as it allows enabling / disabling of features ( gpib / tracking generator / pcmcia )

Assuming of course that the hardware is installed.

[andy_silicon]

Perhaps I'm making progress and we have a fault.

The front end RF module takes 10Mhz , and the input RF to produce a 10.7Mhz IF

With the 40Mhz internal CAL signal turned on - the output 10.7Mhz IF should be -30dBm

i have -54.8dBm.

The front end attenuator performs correctly.
i'm thus down 24dBm of gain somewhere.
The block diagram of the RF module shows several amplification stages ... One of them is 24dBm !

Sounds like the culprit - now which 4 legged microwave blob is it!
( ohhhh for a schematic )

[G0HZU]

Have you checked the match at the RF input port?

I downloaded the block diagram and there appears to be a back to back diode based limiter at the input.

Could this have been damaged by a previous owner? It may wreck the input match if it fails as a short and this would cause a lot of signal loss. You could check its operation with a sig gen and a scope or crudely check it with a DMM.

[andy_silicon]

Yes I have.
I disconnected the RF input to the RF module from the front end protection - and no change.
Also the internal 40Mhz calibration signal switches the RF input off.

I'm going to try and attach some pictures - this may fail.
The amp which I suspect to be at issue is actually a 4 legged white blob with the marking 101.

[andy_silicon]

RF comes in top left.
IF exits top right.
10Mhz in the middle.
Spare port for tracking generator.

Following from the RF port.
Attenuator chain ( with the top rx/tx switch to select the 40Mhz calibration signal
Filter
1st LO Mixer
Filter
Amp (16db)
( hmmm the board and the block diagram don't appear to quite match - corrections later )

2nd LO Mixer and amp (24db)
Following the long path along the bottom
The 10.7Mhz bandpass.
Top right is an MRF5812 (8 pin soic ) before exiting top right.


Yes thats a LOT of Screw holes !!!

I will have to make a temporary cover anyway with a hole cutout to adjust the gain if I replace the 24dB amp.
The service manual say 24db gain , P1dB 15dB.
15v 50mA.

Marking 101 - anybody have any ideas?

[andy_silicon]

Ignore my previous ramblings - the block diagram does fit :-)
I'm looking in the wrong place.

The 24db amp is a tiny 4 pin square device bottom right - after the 210Mhz bpf filter ( string of RC along the bottom ) and before the 3rd mixer ( white blob MCL device right hand side )

So the marking is hard to read
028 or 02B

And I confirm that the board matches (more or less ) with the described bias conditions for this amp.
2 parallel 470 ohm resistors feed the bias from the 15v ( via an inductor )
So that gives 235 ohms over 15v - and assuming 3.7v drop across the mmic - thats about right.
( 11.75V = 235R x 50mA )

[andy_silicon]

Could the device for the 24dB amp be an MRF5711 ?
http://pdf.datasheetcatalog.com/datasheet/motorola/MRF571.pdf

The package style is correct , the bias current is correct , and the gain is correct.
The noise figure is a bit better.

[andy_silicon]

Like this - but with an 8 or B instead of an N.

http://www.ebay.co.uk/itm/380067514769

[KJDS]

I don't think I've ever seen a 24dB gain amp fail in such a way that it became a 0dB stage.

More usually when a MMIC or transistor amp fails it ends up with about 10dB of loss, so I wouldn't rely on the current loss as the fault finding mechanism.

The good news is that there is enough signal loss that it would be easy enough to trace the signal through to find out where it's failing.

[andy_silicon]

Seems a bit weird to me as well.

The problem with fault finding is that the RF module doesn't work with the cover removed.

I will have to improvise with some tin foil/copper tape.

[andy_silicon]

Nope - with the cover off - all self tests fail - no YIG
The YIG is in the RF module - and I suspect without the cover it swamps everything.

I tried replacing the cover with TiN Foil :-) , but same result.

I could remove the part and bypass it ( to see if we lose more gain - or it remains the same ) but I may as replace the part.

KJDS - any suggestions/experience in debugging such units ?

I suppose I could use some thin wirewrap to connect the bias network to an external variable resistor ( 200-700ohms) - then I could vary the resistor to see if the device is working as it should.

[KJDS]

Clamp an aluminium sheet with a 1cm hole in it over the housing to act as a lid. Move it so that the hole is positioned over where you want to probe.

Check with a scope that the voltages are ok on each amplifier. A multimeter probe can cause an RF gain stage to oscillate.

Make up a probe with a 470R resistor on the end of some thin coax. This, when probing a 50R system gives you a 20dB passive probe that won't have much effect on the circuit being tested. With care then this can work ok up to about 3GHz. If you bare the end of the coas so it touches the lid then that will give an ok ground path.

A 24dB fault should be easy to locate, it's hunting down the missing 2dB as that sort of circuit is being designed that's the real pain.

You can check most of the circuit if you've got a fast scope, which will just leave the first IF to check, assuming that it's not an LO driver faulting causing high mixer loss.

[andy_silicon]

Well - I have enough appropriate test equipment  - but there is no way to be able to clamp an aluminium sheet in place ( the RF module plugs into a motherboard - and there is no space.

A full disassembly of the chassis would be required ( the module is between a support and another module ).
I may have to prepare an aluminium sheet of the exact size with some of the screw holes in place.
Then solder a 470R in place and feed through a hole - attach the sheet - solder the coax - put the module in place.

Thanks for the 470R tip.

[andy_silicon]

Minor update.

I managed to get the unit apart enough to do some probing of the RF section.
( and shield the Yig enough to get Yig lock )

The calibration signal is verified at -30dBm as it enters the attenuator chain.

By the bottom of the chain it's a couple of dB down.
After the low pass filter and first amp it's back to -30dBm for input to the first mixer ( a minicircuits MCL-1 )

The 1st seems to be somewhere around -10dBm to 0dBm ( difficult to measure with the probe )

After the first mixer I'm having trouble reliably monitoring the cal signal - will try again later.

[andy_silicon]

I'm beginning to suspect a bodge on the input to the 1st mixer.
There is space for a single smd ( probably an R ).
However three components have been soldered to the board in an hf boost filter.
( R in parallel with C and this combination in series with an R )
If the C has gone bad , it might explain the reduced gain and overall HF fall off.
( about 30-40dB down at 2.7G compared to 40Mhz )

[KJDS]

I'm beginning to suspect a bodge on the input to the 1st mixer.
There is space for a single smd ( probably an R ).
However three components have been soldered to the board in an hf boost filter.
( R in parallel with C and this combination in series with an R )
If the C has gone bad , it might explain the reduced gain and overall HF fall off.
( about 30-40dB down at 2.7G compared to 40Mhz )

What value is the R?

It would need to be huge to cause a big drop in gain.

[andy_silicon]

At the moment I can't easily see ( it's a vertical stack ).
I'd rather be sure before disassembling it - so will check some other things first.

What does concern me a little is that the mixers are supposed to be +7dBm mixers - and I don't see that level at the LO .
More digging.

At the moment I'm only sure it's between the 1st and 3rd mixer   

[andy_silicon]

I think there is at least a problem with the 1st amplifier ( after the pre-amp)
It's supposed to have a gain of 16dB , I'm only seeing 10dB
It's a white 4 pin blob marked 101.
Frequency 3.4ghz , 60mA 4V

I can't find the part number as yet.

Also - I can get the unit to pass the level cal by using the factory menu and setting the value for the expected cal signal level.
So - that would at least seem to indicate the reason for the level cal is purely the gain problem.

I think I've also located the undocumented gpib commands for reading and writing the receiver level correction tables.
There is a correction every 10Mhz from 10Mhz to 2750Mhz.

[andy_silicon]

Nearest part I can find is an Agilent ATF-10136
Looks the same - but the gain is potentially a couple of dB lower.

Hmmm.

[KJDS]

Nearest part I can find is an Agilent ATF-10136
Looks the same - but the gain is potentially a couple of dB lower.

Hmmm.

That gain is specified when matched for optimum noise figure. I suspect that it will be higher matched for best return loss.

[G0HZU]

Note: It's risky to make (fairly precise) conclusions about stage gain when probing 'in circuit' especially up at 3.5GHz.

If you are using the 470R probe then you are measuring voltage gain so you can get confusing results if the amp has different source and load impedances. You could try probing/comparing at the low impedance tap points of each of the little printed BPFs in the first IF. But you can probably still get confusing results when probing here.

Have you ruled out the possibility of gain loss due to instability somewhere?

There do appear to be lots of little bits of (what looks like) RF absorber stuck on the signal path in various places. I assume these are there to suck up unwanted LO harmonics at extremely high frequencies in order to try and reduce the amplitude of internal spurious terms caused by the undesired meeting and mixing of 1st and second LO harmonics at extremely high frequencies. But they might also be there to improve stability in some cases. Have any of them fallen off? Are there any more of them stuck inside the lid?

[andy_silicon]

The cover is full of shielding and black RF absorbers.

Also the 1st LO is 3.4-6.2GHz 

I made an improved probe which is what allowed me to do *any* probing.
( the best / most reliable results were achieved by probing the BPF strips )

Nope - I'm not 100% sure that instability somewhere isn't causing the loss.

[G0HZU]

In case you haven't already done this,  I'd strongly suggest you take a decent photo of the inside of the lid in case any of the absorber bits fall off the lid during the faultfinding

[KJDS]

The cover is full of shielding and black RF absorbers.

Also the 1st LO is 3.4-6.2GHz 

I made an improved probe which is what allowed me to do *any* probing.
( the best / most reliable results were achieved by probing the BPF strips )

Nope - I'm not 100% sure that instability somewhere isn't causing the loss.

The 470R resistor is great in a 50 ohm system to give a 20dB ish loss.

However as you work your way along those filter resonators you get further and further away from 50 ohms, and at the non grounded end then you'll see much higher voltages. I'd disconnect the bias to each amp in turn and measure the level with the 40MHz cal signal again. If it drops further then you know the amp is ok. If it doesn't change much then that amp is likely to be the issue.

[G0HZU]

about 30-40dB down at 2.7G compared to 40Mhz

I think you need to focus on this issue rather than poke around the amps in the first IF because the fault above is most likely to be something wrong in the first mixer or a LO1 drive level issue into the mixer or a fault in the RF signal path leading to the minicircuits mixer (or it could be linked to instability somewhere). Can you trace/probe the RF path through the attenuators up to the first mixer RF input port across 40-2700MHz to look for 30dB loss here at the high end?


Note: If there's lots of absorber stuck to the underside of the lid then this is probably there to prevent (GHz) signals propagating around the unit by reflecting off the underside of the lid. This can cause a feedback path for oscillation so maybe the unit hoots if you try and just fit an alternative bare metal lid (with no absorber fitted).

[andy_silicon]

So - focussing on the high end loss.

I've retouched a couple of dry looking joints and firmly pressed all the rf absorbers down.

Now I have 8db loss at 40Mhz and 22dB at 2.7ghz.

I.e. I lose 14db from 40Mhz to 2.7Ghz. Getting a little better.

BTW all my measurements are with the E4406a VSA at the target frequency and NOT using a wideband power meter.

( the source is an E4437B - and I've accounted for losses in the cable ).
The generator and vsa are known to agree closely within 0.2dB
( when connected by a very low loss N hardline )

[KJDS]

That big frequency slope suggests it's a problem up to and including the first mixer and it's LO.

[andy_silicon]

Last time I measured at the attenuator output it was flat.

So that leaves the first preamp and that 'bodge'

What about the carrier null at the first mixer - could that show as this ?
( I've left that area untouched - but no guarantee the previous owner hasn't had a tweak )

[G0HZU]

I'd advise against meddling with the LO null circuit just yet... I would expect that its function is to boost the isolation (at around 3.4GHz) between the LO port and the 3.4GHz IF1 port on the mixer. It looks to have two trimpot controls in a pair of microstrip tuned sections.

The net idea of this is to presumably to have control of both amplitude and phase at ~3.5GHz in order to deliberately leak the 3.4GHz LO energy across to the first IF such that the leaked signal cancels the internal LO1 leakage in the mixer itself. Without this circuit, if the LO1 was able to leak into IF1 at a reasonably high level (when the LO1 is down near 3.4GHz) it could get amplified in the two IF1 amplifiers and overload the second mixer.

Also the noise sidebands from the LO1 (when tuning down near 3.4GHz) could leak across into IF1 and mask weak signals. So this null circuit is presumably adjusted to null the net LO leakage into IF1 at about 3.4GHz.

Note:
What is a bit worrying about this analyser is that it appears to rely on NVRAM to hold all the factory calibration data. By contrast, all the analysers I have here have a hard coded (default) factory calibration that doesn't rely on a battery. But you can run a user calibration at anytime to allow the analyser to self calibrate all its attenuators and filters etc to allow the storage of an enhanced 'user' calibration and this is backed up in battery backed memory.

So in my case (HP or Advantest analysers) it's no big deal if the (rechargeable) battery fails because you replace it and load the hard coded factory cal data and then run a user cal after that...

But your analyser looks like it will lose all calibration once the battery goes flat... Not good!

If I were you I would contact IFR in the USA with your serial number and ask for all the hardcoded passwords and if it is possible to have access to the original factory calibration data file (for your serial number) so you can reload it into your analyser if your battery has gone flat.

If your battery is NOT flat then be careful not to short it accidentally because you will lose all cal data on the processor board!

I doubt they will let you have their little software program that lets you dump/load the cal data so you may need to reverse engineer the commands to allow a read or load of cal data. If you know anyone who works in a decent cal lab in the UK you might be able to sweet talk them into giving you their copy of the IFR cal software because I assume they must need a copy themselves.

[G0HZU]

In my case I found IFR UK and USA to be very helpful with my old Mi2024 sig gen.

The IFR UK office put me in touch with the IFR USA office that deals with passwords etc and they asked me to phone them at a specific time with my serial number on hand.

They then told me the unique/permanent 'master' password inside my sig gen that overrides everything else. They also sent me the full service manual in pdf format at a time when it wasn't available on the net.

[andy_silicon]

As previously stated - they won't give me the program for calibration.

I have already worked out the passwords ( one of them is in the service manual )
And I'm also quite far into reverse engineering the firmware  O0
I've found the undocumented GPIB calibration table read/write commands but haven't tried them.

Once the factory menu is entered you could manually write down the 300+ calibration values 

Anyway watching the Tour de Yorkshire this weekend - so the IFR will have to wait.

[andy_silicon]

I've confirmed that the the rf path from input to the 1st mixer has a maximum loss of 4-5db (40Mhz to 2Ghz )
Yet by the time we get to the 10.7Mhz IF we have a minimum of 16db loss.

40-500Mhz is flat as shown on the SA. ( but the power on calibration will probably correct the 16dB loss )

After that we have upto 16db roll off til 2.7Ghz.

I note that the Yig is supposed to provide +15dBm but I see about -10dBm.

Unfortunately my equipment only goes upto 4Ghz , and the Yig is 3.4-6.4Ghz.

Would a low level LO cause a problem ?
( unfortunately the service manual doesn't give levels for the 1st LO )

[KJDS]

I'd expect between +7 and +17dBm as the 1st LO drive level. if you can identify the make of the first mixer then it should be easy to check what the drive level should be.

Low LO drive level on a mixer causes the conversion loss to increase substantially from a typical 6dB to a lot more than that.

[andy_silicon]

Minicircuits MCL-1 SKY-60

http://217.34.103.131/pdfs/SKY-60LH.pdf

It's a +10dBm mixer
Or it could be +7dBm
( I'll have to look more closely at the exact model )

[dbloong]

this yig is    micro lambda .

http://www.microlambdawireless.com/

you see yig services pdf.

my  ifr-2398 spectrum analyzer  .  RBW FAIL.........

i need rbw cal

[andy_silicon]

I would suggest RBW fail is a fault rather than calibration issue.

If you look through the thread you will see the passwords necessary to get you into calibration menus.
Use at your own risk.

[dbloong]

My machine I changed the battery backup, backup battery without electricity

[dr equipment]

Hi,

I have a same problem in my IFR 2398. The problem is in YTO or in MCL-1 SKY-60?

Can you send me a zoom photo of MCL-1 SKY-60 and the circuit around?

Thank you 

[WernerFalken]

Old thread, I know, but just wondering if you got this sorted.  I repaired one with level/rbw fails and it was right at the front of the input - one of the AH002R2 switches.  Diagnosing that fault wasn't as straight forward as it sounded.  A lot of wild goose chases!  I went through much of the same frustration with making a riser card/RF adapters to get it functioning so I could probe with another SA.... quite fun.  And locating a NEW replacement of that chip was a PITA....

Depending on the rev, there are two different Ax002R2 chips: AH002R2, and AW002R2, and they are not drop-in compatible for these units.

On a calibration note: IFR told me that these units are hardware designed to self-cal within 1db across the spectrum.  After that, a cal table is used.  From what I can tell, the statement was truthful.  I used a HP 8664A & HP 437B to check it after intentionally wiping the NVRAM, and the repaired 2398 was pretty darned close for hobby work!  Going in and manually calibrating works, but isn't entirely intuitive, so I haven't nailed it down 100% yet.

Anyhow, I started a Google Group to gather info about this model, along with the LG SA-7270A, which appears to nearly identical to one revision.

https://groups.google.com/forum/#!topic/aeroflex-ifr-2398/3C1R7NfneEk

I have a bunch of content there - including some firmware files.

[BravoV]

Okay - the service manual mentions keying in the password "27329780" to get to the factory setting which allows the calibration tables to be cleared before recalibration.

For the life of me I couldn't get this password to work. ( no enter key! )

So after much reverse engineering I now see the bloody obvious.
( once you see that they used a generic routine for entering numbers it was obvious the termination of input was one of the Hz/Mhz/GHz buttons )

It's the "Hz" key to enter the password.

Sigh....

At least on the way I discovered another password for the system menu "72237908"

Needless to say don't mess with these extra menus unless you wan't to wipe out you calibration.


There do appear to be undocumented gpib commands - the work continues.

Aware this is an old thread, just want to say thanks as these both passwords worked at my LIG NEX-1 NS-30, as its originated from Korean LG, before sold to Aeroflex and renamed to IFR-2399

Using that, enabled few 'extra' software features. 

Anyone have the abandoned diagnostic/calibration program for this Aeroflex spectrum analyzer series ?

Few shots of my NS-30 when unpacking while ago.

[WernerFalken]

After many years of on/off work, I just completed the Backup/Restore process for the 2398 (python). As it is fairly similar, you might give the backup a shot. If the unit has its calibration data intact, I'd advise against attempting the restore (of course), but getting it backed up is important.

For the 2398, specifically, the calibration process should be trivial to workout now that the backup/restore is done. Pairing the commands with the service manual should be pretty straight forward, but I am no longer in possession of a fully working 2398... sigh.

PS Much of the seed work credit for this outcome goes to andy_silicon, btw. Without his work, I wouldn't have had to spend time doing this Much of the blame goes to him....lol

[BravoV]

Colby, appreciate the work. 

Is it possible to backup the cal data through the serial port instead of through GPIB ? As I don't own one. 

[WernerFalken]

If you can issue the commands and retrieve the data that way, it should be possible. The returned data is simple text/floating point data that I dump to a file. It isn't some special binary formatted file dump from the machine or anything. Issue a command, read the result, store the data. Restoring the data is similar - just commands repeated for each calibration data element.

I'd like to say that I'd try it soon, but I doubt it. I did keep my one, barely functioning unit out, so maybe some day I'll try.

[tech255]

I have been reading this post with avid interest as i have a 2399b with rf problems the yig test fails in the self test routine so im just about to start having a go at repairing it, i think ive identified the white blob with 101 if you follow this link theres several on the page.

https://www.rf-microwave.com/en/transistors-rf-fet-gaas-fet/

http://www.hp.woodshot.com/hprfhelp/4_downld/products/xrs/atf10136.pdf

Ive got access to a spectrum analyzer that will get to 6ghz but no probe just wondered if i could connect it directly just to measure Whats needed with maybe capacitor or resistor in line.

Any help would be useful
Thanks

[zed dez]

Hello all,

@tech255: From my previous experience with my 2395 (same as 2398 but with a frequency extender 3-26.5GHz) I'd say that YIG Fail is due to the YIG itself. It is part of a PLL and the error is triggered if unable to lock. My unit was overheated (faulty cooling fan) and inside the YIG found some gold wires disconnected (the main coil and the supply in my case). Carefuly inspect them with a microscope. When OK I can confirm the YIG will lock even when RF Synth module is opened and the only conection needed is the 10MHz reference. Also, you can check the 3.2-6.2GHz directly, it is outputed at second upper exit, counting from the IF output. A simple capacitor probe will be enough, and the LO level is very high, you can't miss it. Set the SPAN to zero.

@Colby: Many thanks for your work, helped me a lot for my 2395. It is same as 2398 (even the passwords are the same). I can confirm the GPIB link can be substituted by the RS232. Inspired by your work wrote my own calibration utility and a TRAALL? to display the trace on my laptop and play with it. The 2395 is going up to 115200. At this moment all calib data in my unit is erased, only zeroes.
Still I have 2 problems:
- For the attenuator calibs 0 to 50dBm I'll have to guess a reference for the input test signal, I don't have FCAL2398 to know how exactly is setting the RF generator during calibration steps.
- It is still unclear to me how the YIG slope is determined. I guess the offset is based on the internal test signal by tuning to 40MHZ and then gently sweeping the YIG till it gets a max level value. For the slope a second test at the other end of the band will be required, let's say 2GHz. With a single point it is assuming the GHz/volt curve is perfect linear, that is close but not perfect.
In plus, the 2395 is fitted with a frequency extension re-using the same LO (x1, x2, x4) with extra sweeps to cover the 3-6-13-26GHz bands. At it's input there is an YIG filter that must be calibrated to go in tandem with the LO YIG.
Maybe extra GPIB commands, since I don't have PSOP adapter to read the flash I'll try to boot a linux or DOS, with external keyboard pressing ESC at boot the unit is entering BIOS like a PC

A good new year to everyone!

[tech255]

zed dez.

thanks for the advice not sure if your aware but the 2399 has an extra rf lead to the top of the synth module and as there is no manual available I have no idea what it does, my friend recently dropped off his anritsu spectrum analyser for me to use to find the faults as it goes out to 6ghz.
I will have a look at the yig at the weekend and see if I can see anything loose, not hopeful on finding spares.
have tried to find a company in the uk that can handle repairs but no joy, its such a nice machine would hate to scrap it.

cheers

[George Edmonds]

Hi all

The 2398 is a LG (Korea) re badged product, not an IFR/Marconi.  I believe there is NO support for them now, what there was was a module changing service and the faulty modules went back to LG for repair.

What was Marconi/IFR/Aeroflex/Cobham, is now Viavi solutions Ltd who are only interested in 5G cellular equipment

I have the service manual for a 2399 which should be similar, but it is a module change manual and probably not much help.

73 George G6HIG

[Addie]

Hi All.  Did anyone locate a copy of FCAL2398 - cal backup/restore utility?  Thanks!

[vk2cow]

Hi all,

I have acquired a faulty IFR2398 and after some searching online I found this old thread. The symptoms are similar to those described by others (level fail, the built in cal signal is -42 dBm and external signals are over 20 dB less than expected). I suspect at least one fault at the front end as the SWR looking into the input is 4:1 or worse, which is really unlikely for an instrument like this. Has there been any other development other than those described in this thread?

cheers
Dimitris

[George Edmonds]

 LG 2398 006.pdf (165.2 kB - downloaded 231 times.)

Does this help

G Edmonds

[vk2cow]

Thanks George, this looks like the circuit in my analyser indeed. I am guessing this is from the service manual of the LG version of the same instrument?

[vk2cow]

For the benefit of future generations troubleshooting an IFR 2398.

Initially:

0) All self cal pass exept the Level cal

1) I got SWR 4:1 or worse (antenna analyser looking into spec an input, spec an switched on, SWR the same regardless of attenuation selection (0 to 50 db, 10 dB step).

2) I see the spec an built in cal 40 MHz signal at -42 dBm (should be -30 dBm) and any signal provided to the input of the spec an was over 20 dB less than what it should be.

My thinking:

3) I focused to the circuit directly at the input of the spec an (as indicated by the SWR behaviour). Thanks to George for the schematic.

My actions (so far):

4) I supplied -12 volts to the board, then measured the voltage on each of the two control pins of every AH002R2 RF switches. All of them had ~-8.8V and 0V but the first one had -1V and 0V.

5) I removed the first AH002R2 switch

6) I connected directly with a short jumper to connect the N-type input to the rest of the attenuator chain (pin1 to pin7 from memory).

7) Re-installed the RF module. All self CAL failes exept the YIG - expected as there's no connection to the 40 MHz internal cal signal. SWR is now 1:1 (yey!!!)

Just for fun, added an external 40 MHz about -30 dBm signal to the input of the analyser and rebooted it. It passed all tests! Under these conditions, it behaves as you would expect but the amplitude seems to be out by ~3 dB. Given the dodgyness of the calibration, that's hardly a surprise.

I have ordered a AH002R2 from eBay (fingers crossed) and will report what happens when I install it.

cheers
Dimitris

[doarmin]

Bonjour rien depuis fevrier dernier y a t il du nouveau depuis le remplacement du circuit??
Personnellement je recherche le schemas de la carte vidéo detecteur IFR2398 ref 513-648A.car comportement bizarre autour des capas chimiques
C175 à C177.

[George Edmonds]

Hi

These electrolytic capacitors and a none electrolytic capacitor, plus a number of resistors and an inductor appear to be form just an input filter for the +15VDC supply to the board.

G Edmonds

[George Edmonds]

Hi

Please note that I cannot and will not provide full schematics, here is a partial scan showing the +15VDC input filter.

G Edmonds

[doarmin]

Bonsoir merci beaucoup celà m'aide énormément...J'avais bien vu que ces condensateurs étaient en parallèle mais cette platine a au moins trois couches
et pas simple de suivre...J'ai un peu moins de 6 ohms  aux bornes de ces condensateurs et de nombreuses résistances de 15 ohms  R01 à R08 se sont coupées face à ce presque court circuit une seule semble avoir tenu le coup ...celà explique la présence encore du +15V venant du connecteur de l'alimentation principale.
Résultat : pas de vidéo et échec au niveau du level lors de l'autotest.par contre la Fi 10,7mhz rentre bien sur cette platine  visiblement l'option peack n'est pas concernée par ce + 15V en presque court circuit mais d'autres circuits sur la platine doivent etre concernés mais j'ai pas de détails....ou alors un des condensateurs C173 à C177 défectueux...J'aimerais bien car travail de fourmis autrement.
Bests regarts.

[George Edmonds]

Looking at the information that I have it appears that the +15VDC supply to virtually every IC on the board is decoupled with a 22uf 20V working capacitor with either a 0.1uf or a 0.01uf capacitor in parallel, some IC’s look like they us the +15VDC twice with separate decoupling capacitors.

Regrettably there is no power distribution schematic or a parts list in the information that I have.  May I suggest that you measure the resistance of the +15VDC supply to ground either side of the two 22 Ohms resistors in parallel, this may give you a clue as to if the fault is the filter or is one of the IC supply decoupling capacitors.

All the best and hope that you succeed, if I can help more just ask.

George Edmonds

[doarmin]

Bonsoir.
Faisant suite à vos conseils j'ailevé une à une les condensateurs du filtre puis les découplages du +15V je retrouve encore 2?5ohms par rapport à la masse.
Plus de doute il reste trois CI reliés à cette ligne +15V
U5  U16 et U13 .Plus rien de connecté sur cette platine.A part U5 bien connu un CA2111A les autres ne me disent rien...j'ai besoin d'aide avant de les retirer l'un après l'autre...

[George Edmonds]

Hi

Before I continue may I say that I only have a very limited understanding of technical French and am basically using Google Translator, so certain points are probably being lost in translation.  I also do not have an IFR2398 at present so I am working from an incomplete set of factory schematics.  I do have the IFR service manual, but it is a module replace only manual as all boards/modules were intended to be returned to the factory in South Korea for low level repairs to be carried out

In your last email you said “U5, U16, and U13 Nothing else connected on this plate”.  I suspect that plate should be PCB, from what information that I have there are some 38 IC’s on the PCB with well over 50% using the +15VDC supply, this supply is also used for multiple other purposes and is heavily decoupled with electrolytic capacitor using 0.1uf capacitors in parallel and sometimes just the 0.1uf capacitors.

I do not believe that removing capacitors/IC’s one after another is a valid method of finding the fault as you are very likely to cause damage to the PCB by doing so, my suspicion is that the PCB is at least a four layer one.

In the past I have asked you to check to ground the resistance at either end of the R223 in parallel with R223A.  These resistance measurements should be made using a four wire Kelvin setup.

How you find the short on the PCB depends on the equipment available to you, you need to be able to put a constant current into the PCB +15VDC supply rail and then trace the test current to the fault, there are many ways of doing this, but they all involve specialist equipment that you may not have.  I have an HP set of probes that can inject a pulsed current and then follow the pulsed current about the PCB to the shorted device.

I have scanned the 511-648-A board block diagram and have attached it to this posting.

George Edmonds

[doarmin]

bonsoir merci pour votre réponse.Je vois que vous etes très équipé en matière de recherche de panne...Il y a certes beaucoup de circuits intégrés sur la carte mais après avoir cherché les connections au +15v il y en a seulement 3 qui le sont directement les autres sont à un 5V distribué autrement ou alors il y a une régulation permettant peut etre de fabriquer un +9 10 12 ou autre mais n'ayant pas le schemas...
S'est effectivement une carte avec plusieurs couches et le +15V est distribué ainsi sur toute la carte...En connection directe il y a les trois ci que j'ai identifié après un vrai jeu de pistes:
 Un CA2111A. un MC1350.  et un CA3089.
Oui s'est trés risqué sur un multicouches de sortir un ci traversant comme le CA2111A.En fait la nuit dernière j'ai eu une idée : comme la résistance entre le OV et le +15V est de 2,5ohms j'ai alimenté la carte avec 2V puis utilisé une camera Thermique ce qui m'a permis de voir C154 chauffer puisque parcoutu par un courant de 800mA...méthode certes un peu hors normes mais le résultat est là.Ce condensateur pourtant vérifié etait passé hors vigilance ayant du vernis sur les soudures...L'IFR2398 est reparti comme avant.merci pour votre aide dans cette aventure car j'aurais eu du mal à trouver sans vos conseils.

[vanderleySCL]

Hello everybody,
My IFR 2398 has a problem on the RF input board, specifically the capacitor C1 is leaking, I couldn't get an electrical schematic to check its capacitance, does anyone know how to tell me the value of this capacitor?

[vanderleySCL]

I installed a 10N capacitor (103) while not finding the correct value and it seems to work fine. But I still have another problem which is an error in LOG calibration. This problem seems to be in the attenuator because the REF LEVEL when above 10Dbm as measurements are correct but if I change to 9.9DBM (or any value below 10DBM) as measurements are incorrect, the signal a drastic reduction. If anyone has the attenuator schematic and can share it with me.

[George Edmonds]

Hi

C1 is a 1mfd none polar capacitor 25vdc working.

I posted the schematic of the attenuator previously, look back at my earlier postings.

Looks like this 2398 has had a DC input overload.

G Edmonds

[vanderleySCL]

Thank you very much Edmonds, I will provide the correct value of the capacitor, you are right, it suffered an overload on the input, the error problem in the Log I was able to identify, it is a 20DB attenuator relay that is damaged (Teledyne a150-20-12) , I made an external attenuator just to test and it passes the self test, now I need to buy this relay. Very grateful for the support.

[EB4CUV]

Hi George

I bought an IFR 2398 with a fault and I'm seeing that the input step is blown. In a previous message you said that you had posted the schematic of this input board but I can't find it. Could you send it again or tell me where to find it?

Thanks, Julio.

[George Edmonds]

H

Reoly #54 in this posting.

G Edmondsi

[EB4CUV]

Hi George,

Sorry for the inconvenience. In that post #54 the attached .pdf is from the rceiver front-end board and I don't see any other archive.
The schematic that I need is of the input board where the N connector is and not for the front-end because the diodes are burned.

Thanks,
Julio

[George Edmonds]

Hi Julio

Having now had a little time to look at your photograph I would be very surprised if this is the only damage.

At present I cannot provide a schematic of the input assembly, but you do not need one, just a little information.  The only RF path components are C1, DC blocking capacitor which is a 1uf at 25V device and the two catcher diodes CR1 and CR2, these diodes are MSMP-3892, data sheet attached.

All the rest of the input assembly is providing a plus and minus reference supply derived from the main instruments + and – 15VDC supply.  CR3 and CR4 are MMBZ5232LT1 Zener diodes.

Regrettably I suspect that there will be further downstream damage, particularly to the solid state switches.

Hope this helps

G Edmonds G6HIG

[EB4CUV]

Hi George,

Thanks for your help George. People like you make life easier for others.

I've removed the bad diodes from the input board, leaving just the capacitor until a replacement arrives.

Your suspicions are true. The first solid state switch on the front end board is damaged.
I have done what vk2cow said in post #56, remove the first AH002R2 switch and bridge pins 1 and 7.

Now, I inject a 40Mhz and -30db input signal into the N connector and the device passes all the tests correctly.
I'm on the right track.

By injecting other signals, the device measures almost correctly. The next step is to do a good calibration.

The next question is: where can I find the calibration software or some other that can handle the device?

Again, thank you very much for your time and help. I hope my experience is useful to others as well.

Julio, EB4CUV

[Ron Castle]

Hi George,

Ours is working but the center of the screen is all washed out. I guess I can use the video out would you know what the display P# might be.

[Electro4lease]

Hello,
You can replace only the LCD screen ref.: SHARP LM64P101 easy to find on Ebay for $150.00.
We have one unit in stock (used but working) we can ship without CCFL backlight if yours is working. Price: $100.00
Best regards.
Antoine