Bye, bye, SARK-110

It's been a lovely antenna analyser.  But today, after five years of service, it was time to say 'goodbye' to the SARK-110 analyser.  This is not to be confused with other analysers going under a SARK name.

I've had doubts over the reliability of the 50MHz results from the SARK-110 for a while now.  The cause is most likely to be the remarkably stupid use of a MCX connector.  This has long been identified as a problem with the SARK, and one that, so far as I know, years later, still hasn't been rectified. 

A great analyser, let down by a simple design failure.

 

MCX connectors have a very low connect/disconnect rating - it's only about 200 or so.  Even when we add a pigtail extension to avoid any disconnections, the connector type is still extraordinarily prone to stresses and intermittent connection failure, usually manifest as noise on the trace.  When you look at the male connector side, you wonder how this ever became a connector for anything, let alone sensitive RF measurements; it literally relies on some weak springy leaves of metal and weaker friction along a very narrow ring at the end to maintain the connection.  It's a connector type that should be consigned to the great design failure bin of history.

Rubbish.  MCX male (the SARK end is female).

The first sign of problems came a long time ago at 50MHz, when I tried to cut a replacement matching 75 Ohm stub for my 2-ele quad feed using the SARK's facility for that process.  I never found the correct length using the SARK, which kept reporting the same results, regardless of length.  I shrugged my shoulders and just copied what I already had in place, which had corroded.  But I ought to have looked more closely at what was going on.

I don't know for sure, but either the SARK has a firmware problem, or the MCX connector isn't reliable at higher frequencies.  Whatever the cause, I couldn't get a reliable output for 50MHz from the SARK, no matter what.  This was most recently evident when trying to make a 6m magnetic loop; I couldn't ever get a match with it according to the SARK.  But I've made dozens of loops, and I know it isn't my lack of skill in this case.

As a final attempt, I tried soldering a pigtail extension directly to the MCX connector body.  The SARK is very small indeed, and getting all the plastic push-buttons, especially the power switch button, to line-up again is a massive headache.  When I thought I'd succeeded, there was no change - except the display had now gone south, despite wearing a static-draining wristband whilst working on it.

Well, the only destination now was the bin!  

Was the SARK-110 a good unit?  Yes, but not at 50MHz.  It might have been peculiar to my unit, but that MCX connector - and the extremely small size of the SARK - were always two big problems, especially when the average age of a ham operator is well into retirement territory, where fingers and eyes no longer work as they once did.

There also has to be a question - and I put it no stronger than that - about the generic look and some components of the SARK; it has similarities to other Chinese vector analysers that cost only about £50, which also have accompanying PC-based software, just like the SARK.  

I wasn't going to chance the sometimes poor quality control and unknown effectiveness of such branded units this time, when I need a known, good quality analyser to continue antenna work.  But I might well try one in the not-too-distant future, just to see if our expectation of having to fork-out £400 for a antenna analyser is just misguided.

My analyser for coming years.

Of course, Seeed Studio - the maker of the SARK - is itself Chinese, based in Shenzhen, where so much of the world's electronic gizmos are created.  Their stated mission is to provide "open technology", which may explain the similarity of the SARK to the E-bay VNAs.

Was the SARK good value?  Well, I go on the calculation of the price, £350, divided by the number of years it worked reasonably well.  That comes out at £70 per year, or about £6 per month to have the use of an antenna analyser.  I think that is not too bad an outcome, when I think of the considerable time, frustration and wire that has saved me.  It's fair to say it has paid for itself.

What next?  Well, I was very close to buying a RigExpert - a fine Ukrainian product -  last time, and so I've given them a chance now and have a AA-230 Zoom unit in the post.  We'll see how well that does over time.  At least I'll no longer have the world's most idiotic connector and tiny buttons to contend with!