Tag Archives: review

The RigExpert AA-230 Zoom

One page that folks following my blog seem to gravitate to is my review of the Mini60 antenna analyzer.It is the Sark 100 copy sold on Ebay and produced in China. I personally have found this analyzer to work quite well and I have used it exclusively to test out my antennas. Your mileage may vary.

Now that I am doing some additional antenna work I have purchased a RigExpert AA-230 Zoom. This unit is a bit pricey compared to MFJ units and certainly to the Mini60 but from what I have done with it thus far it is well worth it. I’ll publish a comprehensive review later but for now I am sold on it. It is light, provides accurate and quick scans, has an impressive array of features including cable TDR testing and a great USB interface. The software works great with a PC and can save files in a format that Zplots can read.I used it for the first time in the field on the 40m loop and it made short work of tuning it. The interface takes a little getting used to but overall is very smooth to handle.

I will not be getting rid of the Mini60 as for quick and dirty measurements it still can’t be beat for the money. The RigExpert will be for more advanced testing and data collection and will of course help me with 2m antenna work.

aa230zoom-sm1

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Enter the Flea Market HDTV Antenna

Our local flea market. 77 flea market, has several vendors selling homemade HDTV antennas that are constructed from PVC pipe, and electrical flex conduit.The sell anywhere from $8-12 and of course the final price is negotiable. There are three versions being sold, a dipole, a loop and a “double loop”. I bought a dipole and the loop just to play around with thinking I could debunk them as any viable antennas for this application as I had already tried some store bought amplified antennas with little success.Here is what they look like:

photo-nov-05-2-16-30-pmphoto-nov-05-2-16-10-pm

I bought both for $14 and both came with a 8ft length of coax with a pretty decent set of connectors done with good workmanship. I took these home and connected to my TV and started a channel search. First up was the loop up about 7 feet. To my complete surprise It captured 30 stations including the ABC and CBS stations!  The dipole was a little worse but comparable to the amplified antennas I had previously tried. Given this unexpected performance, I decided to look into how these antennas go together.

Essentially the dipole is two lengths of wire cut for the 800Mhz range and connected to a 300 Ohm to 75Ohm transformer. The loop is similar with a length of wire looped and connected to a transformer.Here is what one half of the dipole looks like:

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I can say the workmanship is good with a solid crimp to the wire element. Clearly the wire element configuration doesn’t make much sense.  When this is jammed into the PVC pipe the ends will short together and yet, there are likely some case where the wires may not short. It seems that it would have made more sense to just use a simple length of wire.

 

 

Review of Mini60 Antenna Analyzer

I mentioned in a previous post that I had purchased a Mini60 antenna analyzer. I am going to post a quick review on this device now that I have had a chance to use it. The Mini60 is a Chinese made copy of the Sark100 antenna analyzer developed by Melchor Varela, EA4FRB. This was originally an antenna analyzer provided in kit form. He has since discontinued production of the SARK100 kit and is now building a much better featured analyzer called the Sark110 which sells for about $389. It should be noted that although the Mini60 is a derivative of the Sark100, Melchor provides no support of any kind to these devices nor is he associated with their manufacturers.

mini60

The Mini60 is sold on Ebay from a variety of sellers with the average street price of about $130 delivered. This review focuses solely on the ones marked Mini60. I mention this because there are similar devices marked as SARK100 that also sell on Ebay for about $100. The Mini60 arrived at my QTH in a box and was wrapped in bubble pack. Nothing else arrives with it. No manual, no cables…just the device itself. It turns out that the instructions for operating the SARK100 apply completely to the Mini60. The following are links to the most useful files available for the Mini60:

The SARK100 Manual

The SARK100 Basic PC Control Software

Zplots for the Sark100

The complete archive of the Sark100 can still be found on Melchor’s website here. Regarding the manual, you can skip the sections devoted to assembly and test of the Sark100. The interesting bits are related to how to operate the Mini60 as well as items in the appendix on using a serial link for PC control. The Basic PC control software is DOS based software which allows you to run a sweep across a range of frequencies and saves the collected data into a comma delimited (.csv) file. This file can be opened within the Zplots Excel spreadsheet for graphic display of a variety of antenna measurements. Note that the Mini60 can be used stand-alone but the addition of the PC based sweeps provides considerably more data across a wider range of frequencies.

The Mini60 is powered either by its internal rechargeable battery or by an external 12V power supply (not included). I typically plug the Mini60 into a USB port for charging of its internal batteries. One thing to be careful of is that if the device is left on for more than a minute or so it shuts down to save power. It is important to note that this only shuts down the display and continues to draw current if the power switch remains in the “on” position. The timeout can be adjusted but I have on occasion drained the batteries by forgetting to switch the power back to “off” after a timeout.

The Mini60 is built solidly with a sturdy metal case. It is about the size of a pack of cigarettes. There is a single PL-259 connector for attachment of the antenna or feedline, a single power switch a mini-USB port and an external power port for 12V DC. Upon Power up it displays frequency, SWR and impedance magnitude. The device powers up in impedance mode by default. Other modes include complex impedance, capacitance, inductance and off mode. The off mode can be used to measure any RF feilds in the vicinity. Frequency coverage is from 1Mhz to 60Mhz in 13 bands. Pressing scan will scan across the selected frequency band and will beep when an SWR match below 2:1 if found. After a successful scan, the device will display the bandwidth and be set on the frequency of the minimum SWR found.

The Set button allows the device to adjust step size, suspend timeout, calibration and the PC link functions. I’ll describe the operation of the PC link functions is a separate post.

Overall, I have found the Mini60 easy to use. I verified the output frequency with an oscilloscope and found good matching. The default suspend timeout is a bit short but is easily extended. I like the USB charging feature and PC link function. The PC link feature is a key feature for me and now that I have used it I would not want to use an analyzer that did not have some sort of data download feature. The analyzer made short work of setting up a homemade Buddistick antenna on both 20m and 10m and is very useful in comparing actual with modeled antenna results.

The only negatives I have noticed have been fairly minor. Adjusting the frequency is a bit tedious particularly at the band crossings. This can be compensated by running a PC link sweep but that is not always convenient as a PC is required. The Inductance measurement feature on its own is somewhat strange. I get different readings on different bands. I ultimately used a series RLC circuit with the L being unknown and running a frequency sweep with the PC link feature. It is fairly easy to find the inductance value by reading the frequency of minimum SWR on the sweep and calculating the Inductance value. I’d say that the inductance values are only good within 15 to 20%.

For $130 this has turned out to be a handy and useful tool. Used analyzers can often be found for similar pricing but lack the PC link feature that really differentiates this unit at this price point. I plan to keep using it and will update if there are any quality issues noted down the road.