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Author Topic: Panaxis FME 500 issue  (Read 3224 times)

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #30 on: August 23, 2018, 1724 UTC »
All electrolyitics were replaced as were all Tantalum.
The 3 trimmer caps are also brand new.
I am left with diodes and ceramic caps,resistors and the last 2 IC chips that should be in about a week.
I can not find the MV2113 diodes anywhere and will be the last to blame soon :)
Going to for sure change out the pair of 4148 diodes today along with the 3904 and try again.
Then hunt down some ceramic disc caps.
Will post what happens after that.
Jim

Offline JimIO

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Re: Panaxis FME 500 issue
« Reply #31 on: August 23, 2018, 1757 UTC »
Is there a "theory of operation" section in the manual? I can make out the path from the oscillator into the PLL chip and from the PLL chip to the varactor diodes D1,D2 but the rest is not so easy. What part number is the PLL? What happens when you vary R22?
(I think it's 22, not R5)

Offline KaySeeks

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Re: Panaxis FME 500 issue
« Reply #32 on: August 23, 2018, 1931 UTC »
The diodes to my knowledge can be either 4148 or 914`s and the 2n3904 can be swapped with 2n2222.
I already replaced the larger RF transistors and just the 3904 left.

Though they are similar, I would be a bit reluctant to blindly replace 2N3904 with 2N2222. 2N3904 is a bit more optimised for higher-frequency operation and 2N2222 is a just a general purpose switching transistor. They do not have the same frequency characteristics and do not have the same input and output capacitances. Hfe peak occurs at a different Ic so it will operate differently and switching characteristics are a little different.

If you are replacing Q3 in the schematic you showed earlier then it may not matter as it appears to be a simple DC application, but Q1 and Q2 may be dependent upon the characteristics I mentioned above. In any case, it's not clear to me what Q1 and Q2 have to do with the PLL going unlocked anyway since those are the driver and final amps.

Just somebody with a radio and a pair of headphones...

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #33 on: August 23, 2018, 2001 UTC »
Is there a "theory of operation" section in the manual? I can make out the path from the oscillator into the PLL chip and from the PLL chip to the varactor diodes D1,D2 but the rest is not so easy. What part number is the PLL? What happens when you vary R22?
(I think it's 22, not R5)

Send me an email and I will send the full manual with theory of operation.
wtfbsyt AT gmail DOT com


Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #34 on: August 23, 2018, 2006 UTC »
To "KaySeeks" -
I was not sure about using the 914 diodes over the original 4148 but wanted to try.I may put the old ones back in since there was no change.
Same goes for the 2n2222...going to put the original 3904 back in as that also made no difference.
The driver/final transistors were replaced with original values the first day I tested it out thinking they were bad.
So far,it does even less than it did before I removed the IC`s and cleaned the sockets. Now thinking the sockets have an issue as it does nothing since messing with them.The new chips make no change.
This is getting ridiculous now but somehow it keeps sucking me back in :)

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #35 on: August 23, 2018, 2154 UTC »
After all the work done,damn thing is doing less than it started.
Ever since I tried to clean the sockets,it now does almost nothing now.
Going to walk away from it until the last 2 replacement IC chips arrive.I may remove all IC sockets and solder the new chips in directly to the PCB.Not going to spend another dime on this thing and if it works it works,if it does not work...will be nothing more than an old memory.
Thanks to all that had ideas.If it ends up working,will post it here and if you hear nothing from me again,then it is DEAD !!
Jim

Offline ChrisSmolinski

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Re: Panaxis FME 500 issue
« Reply #36 on: August 24, 2018, 1154 UTC »
Looks like I am SOL regarding the MV2113 or MV2114 diodes.
Can not find them anywhere.
Jim

Become the MV2114 King!   https://www.ebay.com/itm/MOTOROLA-MV2114RLRG-TO-92-TUNING-DIODE-NEW-QUANTITY-100/150969981739
Chris Smolinski
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eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 270 ft west-south-west beverage / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #37 on: August 24, 2018, 1159 UTC »
Wow,that is a lot of diodes,but you found them !!
Wish he sold only a few...but tempting.
Thanks for finding that...may be forced to get these.
Jim

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #38 on: August 24, 2018, 1249 UTC »
Here is a question.
The original PLL is a DS8907N.
I found some time ago a DS8907J and the datasheet looked the same to me,unless I am missing something here.
I just found this - https://www.ebay.com/itm/Phase-Locked-Loop-Frequency-Synthesizer-IC-DS8907-DS8907J-NEW-/222132344468http://
Is it safe to say they are the same part and function?
Jim

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #39 on: August 24, 2018, 1417 UTC »
Another fresh look this morning at this situation with a clear mind.
The 4 mhz crystal was replaced with new,but for fun tried another slightly different in freq,same results.
The oscillator works.
According to manual and "pre-flight testing" procedure,I am to power the circuit without IC`s installed and tune for 100mhz.
This is possible.
With all IC`s in place,it requires me to tune the output trimmer caps a bit and it transmits fine,but PLL is not locking.
I find harmonics of freq across some portions of the band but strongest @ near 100mhz.
I jiggled the PLL chip back and forth to see if it is bad connection and it does cut off and on and LED flickers.
Almost seems the IC sockets are dirty or worn and will order new as they are cheap and replace all sockets.
Looking over some ceramic caps,some looked a bit beaten from all the work being done,so replaced them anyhow.Mostly the oscillator stage caps which are .1uf.The other caps look fine physically.
Besides the pair of MV2113/14 diodes,going to leave those for the very last effort as they are costly.
Until the final 2 IC chips arrive and new sockets installed,will know more...going to be a week or 2 though.
Will post results ASAP.
Jim

Offline jta

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Re: Panaxis FME 500 issue
« Reply #40 on: August 25, 2018, 2249 UTC »
I took a look in my parts bin hoping I had some MV2113 or MV2114s. What I do have is a pair of MV2109s and a pair of MV2115s. If either of those will work for you, let me know and I'll be happy to send 'em to ya.

OTOH, I highly doubt that these are your problem.

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #41 on: August 26, 2018, 1229 UTC »
That is nice of you to offer.I also do not think they are the issue,but at this point in the game,willing to try anything.
the MV2115 may work,but lets see what happens when I replace the IC sockets and install all new IC chips.
Again,this thing worked 100% before it was put away for the last 18-20yrs.
Replacing caps seemed to be the obvious things to look at.But then again,maybe the caps being so poor over time destroyed other things when I powered it up?
I need to see if the PLL chip is good and the replacement I bought could have met the same fate and may need to hunt down another.
Will post more soon as I new materials show up here.
Jim

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #42 on: August 29, 2018, 2123 UTC »
Today the IC sockets arrived and soldered them all in nicely.
Inserted all chips that have arrived new except for one which I am still waiting for.
PCB is nice and clean and went through it with magnifying light with fine tooth comb for bridges,cold joints or broken traces.
Powered it up and still not locking !!
Running out of new stuff to try except all resistors and ceramic caps plus the pair of tuning diodes discussed earlier.
Could it be that last IC that I am waiting for?
Or could it be both PLL chips are DOA?
I just ordered yet another PLL but maybe it is not actually the same type?
I remember comparing datasheets between the original DS8907N vs DS8907J and finding them the same,but maybe I missed something here?
There is another company that sells the "N" type but minimal order is 2 pcs @ $112.00 each...they can keep them for that money.
I bought another one like this instead thinking whatever ruined the first did the same to the new before going through all the components.
https://www.ebay.com/itm/Phase-Locked-Loop-Frequency-Synthesizer-IC-DS8907-DS8907J-NEW/222132344468?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
Gonna be awhile for that to get here and the last thing I try.
Oddly,with all IC chips removed I am to tune for 100mhz,then insert all IC`s in sockets.What it is doing now is showing up on the frequency I have the DIP switches set to...weird because when I touch the finals,it drifts off freq.
Something is whacky...maybe me :)
Jim

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #43 on: August 29, 2018, 2249 UTC »
Did another run through...all looks fine.
Put the PCB back into the casing and tried again,but this time,with the FM receiver without a antenna connected.
I use a Yaesu FT897 with no coax about 3 feet away.
I should have done this before to eliminate harmonics being so close.
Anyhow,I only find the signal strong near 100mhz right where it is supposed to be according to instructions BEFORE IC chips are installed.
I am to tweak a coil by squeezing it closed or open and using a variable resistor adjustment for 100 mhz with pot @ 12 `o clock.
Without trying,it was @ 101.3 mhz,twaeked it a bit for 100mhz and solid around there now.
But the IC`s are in place,so obviously,no PLL lock.
I am beginning to think the PLL is just bad...both of them.
It sure does work much better,except for the locking part.
I have one chip due here in a few days and will drop it in and try again for miracle...then have to wait for the other PLL.
I may as well try the MV2113/14 diodes...or 15`s at this point.
Jim

Offline N2NXZ

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Re: Panaxis FME 500 issue
« Reply #44 on: September 01, 2018, 1741 UTC »
Lat IC came in today,plugged it in...still no change.
I have already spent more than I like on this thing so the last chance is the new PLL .
Then it becomes an expensive paperweight.
I have other projects to invest time and money into and this one is not priority.
Jim