Sark100 Antenna Analyzer Repair

Repairing a Sark 100 Antenna Analyzer that I bought from Ebay. It came in broken I decided to see if I could fix it and not waste $80. This is a good lesson on simple RF tracing and what can be done with just a little knowledge and the right tools. The entire repair only cost $8.00.

[@warplanner3258]

I gotta tell you that this video was absolutely helpful! I got one of these from eBay and it developed a problem with the display missing a line of pixels rendering the readings ambiguous sometimes. I was about to trash the unit until I saw your video and said, "what the hell!" I wicked out the old display and replaced it. (They are a fairly common type.) When back together, it came up with the "green screen of death" message you got. I was about to replace the AD8008 when i noticed one of the SMT 0.1 caps had been nicked off the board by an errant screwdriver during my reassembly. No problem. I replaced it with a very small through-hole tack-soldered neatly onto the pads. The beast came up and worked great! Cut to six months later when I accidentally knocked the unit off my bench, kicked it underneath, and a portable table fell on it, destroying the switch. Again, no problem! Seems one of these small SPST switches fit **exactly** in the hole and, when tacked onto the board, is flush with the top panel. A nylon washer and nut and Bob's your uncle! So..don't fear the reaper! Love this little analyzer!

[@AERVBlog]

Wow! Poor thing has been through heck. I am glad you got it fixed. Glad I could help too in some little way. Thanks for watching.

[@warplanner8852]

@@AERVBlog..well, the saga continues! Just recently, I reverse-polarized the little fellow (got the power leads switched) and it fried the U11 7805 regulator. My friend, WB6JDH, helped me troubleshoot it and replaced it with a TO-220 version of the D2PAK chip and it was revived and purring along nicely. Inasmuch as I have a Mini60 coming, I gifted Dick with the unit where it will be put to good use. We have renamed it from Sark100 to Laz100 - as in Lazarus in the bible, the man that Jesus waked from the dead. These truly are rugged treasures and fun to work on! Again, many thanks for your video and inspiration. Please look for a comment on your HP403B video re how I replaced/upgraded the stock batteries in the voltmeter with cheap ones easily found on eBay.

[@jasonmiller-nr8dw]

i have one of thses and i havent had any problems with it besdes hooking it up to my pc and updating the software on it. if i had this problem i would have sent it back. thank you for showing how to fix it if i get that code on mine.

[@johndminigan1869]

Got mine in today, it worked out of the box. Thank God it did. I do not have your skills and would be disappointed if it was yet another dud that I seem to get lately. Update. After using it for a few hours and doing the calibrations as per. Requirement. I found out all the swr Measurements for coming back at 1.3 swr. So in fact the unit is Faulty, so I asked for a refund.

[@AERVBlog]

I am glad it worked for you. It can be a useful little box for sure.

[@johndminigan1869]

@AERVBlog After doing the Calibration, All SWR readings reads at 1.3 to 1 I did not know I had to recalibrate. After going out and buying resistors and building the short dummy plugs only to find out that don't work. This should be done at the factory. I am sending it back for a refund.

[@AERVBlog]

@@johndminigan1869 sorry to hear that. I bought an MFJ-259D that is a whole lot easier. It is not as functional though.

[@terrycrabtree3779]

NICE JOB. A FEW MINUTES OF WORK REAPS BIG REWARDS

[@AERVBlog]

Thanks. I actually ended up getting this thing for free since it was DOA. The seller didn't want it back.

[@whamni]

Great video and very helpful. I have the same problem, but I don't have the right tools or more to the point the eyesight, that's a small chip ! . I don't want to bin the Sark , so if anyone knows of a repairman in the UK, let me know and thanks in advance 73.

[@fenderblues1744]

Enjoyed your video and repair. I have a Sark 100, worked OK at first then one day it came on with the first screen but does not go any further. I wounder if you have any idea's. Please.

[@AERVBlog]

It depends on what the screen says when it is starting up. If it looks like the screen in the video it is most likely that IC. More details please.

[@fenderblues1744]

Hi thank you . The reading on screen. Sark 100 Analyzer (c) EA4FRB 11 V13, this stay's on for 2;15 sec then words go off and yellow light stay's on, with no auto switch off. Are you in the UK.

[@AERVBlog]

No. I am in the US. I don't know off hand what might be the problem with your Sark but I would start by checking voltages.

[@fenderblues1744]

That's a shame. I wouldn't have the soldering skill's to repair it. I thought about buying another one but may go wrong again. But when working was really good. Thank's for your help.

[@AERVBlog]

If you were in the US I would say just ship it to me and let me see what is wrong with it since fixing it would probably be cheaper than buying a new one but the shipping cost would negate any savings. Too bad. Better luck next time. Look into the MFJ analyzer. They don't give you quite as much info but they are a lot easier to use.

[@stewartrv]

Hi you mention you got a circuit diagram - PCB layout. Where from? Can you post the link or add to the description please?

[@AERVBlog]

stewartrv I am away for a couple of weeks but I will send it when I get back. Ok?

[@AERVBlog]

I found it. Contact me at [e-mail] and I will email the manual to you.

[@worldradio456uk5]

Hi there. I have the Sark 100 here . But iam having problems calibrating it. The 50 &150 ohm reads ok on the meter but the 274 ohm resistors reads 340 something ohms on the meter ! I've checked the resistors with a good meter and all is ok . It's just the 274 ohm resistors that doesn't read right. Have you seen this fault before? Any help would be great. 73s.

[@AERVBlog]

worldradio456 uk I have not seen the fault but I will check on it. I am away for a couple of weeks but I will get back to you when I return. Thanks for watching.

[@worldradio456uk5]

Thank you for replying . I know this is an oldish thread so thanks for that . Hear from you soon have a good trip. 73s.

[@marcelobahl7655]

Hello noble friend, I have one of this model and he is presenting the following defect as reported below: Normally, it does read, but does not read correctly, I do not know if the problem is software or if it is hardware. Could you please help me with some idea of what might be happening, and or where can I download its firmware to try to solve the problem if it is internal software? I'm in Brazil

[@AERVBlog]

Marcelo Bahl wow that is the first time I have been called noble. I think I like it. Please send me pictures of the screens you get when it boots up and what you get when you try to measure an antenna along with the actual antenna parameters. Send them to [e-mail]. I will see what I can do.

[@trinitron11420]

I own one of this, calibrated the unit but when I check my antennas it gives me false readings, don't know how to tackle the problem, any ideas?

[@AERVBlog]

Sorry. I don't really have any ideas for you. I got rid of mine for a MFJ. It is much easier to use.

[@surfnutt]

I have a sark 100 and the other day plugged the 12 volt lead in and it was the wrong polarity there was a snap and i opened the case to find a little chipthat has blown its says u11 on the board next to it i removed the blown chip but need to find out the part number to replace it any help would be appreciated i have a photo of the part in situ before removing it.

[@AERVBlog]

U11 is an LM7812AC voltage regulator. Mouser has them for less than $1 each. I would not be surprised if there are other blown parts in there too as there is an LM317 (L9 i think) attached directly to the positive input. Also check the 2 diodes. One is just after the U11 and the other is just before the U9. Good luck and thanks for watching.

[@surfnutt]

@@AERVBlog Thank you for replying i have ordered a replacement part everything else looks ok i am a novice i have a multimeter but not sure how to check the diodes with this. Regards Ian

[@surfnutt]

@@AERVBlog received 5 x lm7812ac in the post in 8 days from china for £5.83 inc postage and after 2 minute soldering job the unit now works like new thank you for your help regards Ian

[@AERVBlog]

@@surfnutt Great. Glad that was all that was wrong and that I could help in a small way.

[@donselbe5812]

Where cal I get parts for a mini60 antenna analyzer with Bluetooth? I bought one on Amazon 2 years ago and it didn't have a battery, battery case, charging circuit or USB connection inside. Tried to contact the seller thru Amazon and they went belly up. Amazon couldn't help me so I have a $130.00 piece of junk.

[@AERVBlog]

I don't know but let me look into it.

[@donselbe5812]

@@AERVBlog I would appreciate it. de KE8JMS

[@jkbish1]

i got one and it is not consistent, suppose I need an engineer?

[@AERVBlog]

What is it not consistently doing. I would not buy one of these now. Spend the $50 and get a Nano VNA. So much better.

[@jimawhitaker]

It has it all, who dunnit, thrill of will he be able to remove the device and will it ever work? I really did like the video as I'm legally blind and surface mount is way beyond my skill level ;-)

[@caulktel]

Jim Whitaker i

[@johnroland51]

For those of you that don't have 20 minutes to invest. He replaced an AD8008 chip and it solved his problem. Hopefully that was the only problem.

[@AERVBlog]

Yup. It was. The thing is still working just fine. Thanks for watching.

[@steffenhansen3179]

Hi good afternoon ! Can you do my checking and if necessary repair

[@AERVBlog]

Steffen Hansen I would be glad to take a look at it for you. What is it doing wrong?

[@steffenhansen3179]

Hello! Example: Measured set antennas and it shows utopian values. original 1: 1.4, sark shows larger than 10 Maybe just check it out? But come from Germany, ship?

[@steffenhansen3179]

I have already compared with Dummyload

[@steffenhansen3179]

Me again . I just see you are in USA! Since shipping is not cheap.

[@steffenhansen3179]

pity that you are so far away

[@richardkitchen4430]

My sark was working fine, then just quit will not come on at all.

[@AERVBlog]

They are not great. The idea is good. Check the voltage regulators and fusible resistors.

[@youtubeaccount7544]

Couldn’t fix this pos so I broken it into pieces and threw it away.

[@AERVBlog]

Awww. Too bad.