Wednesday, 28 January 2015

The £10 external meter for the Yaesu FT-857/897

It was find a birthday present for one of my Amateur friends, well he is going to be 70 in a few weeks, so it was time to look for something useful or interesting.  A bottle of Scotch maybe or a woolly hat? Then I had a thought he owns a Yaesu FT-897, and I had seen the Chinese selling external meters on ebay for this radio. There are two versions available, white backed scale, or black versions. I decided to take the risk and send for one in black, will it arrive here before his birthday? It did! It was delivered in less than 10 days from HK, although the sellers address was Shenzhen China?

The analogue meter replicates everything you see on the digital bargraph meter on the front of the FT-857/897 (S, PWR, SWR & ALC).

First thoughts not bad, quite weighty, excellent black anodised metal case, with a 3.5mm jack to plug into the external meter socket under the VFO knob on the front of the FT-897, or the left handside bottom front ext meter skt of the FT-857. It was time to take the roof off and have a look inside, well I did want to make sure it was ok for him?





There is plenty documented on the Web about making an external meter for these radios and really there is not much to it. But the Chinese have really made a very good job of this for the money, its not just a meter stuck in a box, they have taken their time to produce a little PCB with the calibration pot which can  be easily accessed from the rear of the case through a small hole. The PCB has then been bolted across the two rear meter terminals and it is a real solid job.




There were no instructions in the box that it came in, but these are well documented at the bottom of the ebay sales literature, and reference to all of this is set out within the Yaesu manual.

Conclusion: Well made and produced for the cost, you would find it very difficult to get all the bits together including the case and build it for the price. I wasn't able to test it out as I don't own either radio, time to wrap it up and put some kisses on the birthday card.

Reference:

http://www.ebay.com/itm/New-External-S-meter-SWR-Power-meter-for-Yaesu-FT-857-FT-897-Black-/121480229454?

Friday, 16 January 2015

First thoughts of the MF500B Multimeter

Delivery came quick! I ordered the meter at the end of the festive period from Banggood on the 29th December 2014, it just took 16 days to arrive to my home in the UK. It came well packaged, surrounded by plenty of polystyrene wrapping and housed in a sturdy polystyrene box, which does show signs of plenty of bashing through its travelling trip on route from Singapore.

For the cost of £20 ($30 US) it looks and feels like a more expensive meter, but do looks deceive?

The movement is good, you can tell this by moving it from left to right and noting that it is well damped and returns slowly to it zero position, the range selector knobs and switching has a professional feel and click into position.



The manual isn't up to much, as 99% of it is written in Chinese. I am able to decipher that it is an Industry standard 20'000 Ohms/V meter on DC +/- 2.5% , except 2500V @ 4000 Ohms/V.  On AC ranges it is 4000 Ohms/V +/- 5% accuracy.  DC Current (I) is +/- 2.5% & AC Current +/- 5%.
Ohms measurement +/- 2.5% accuracy.

Batteries required for Ohms ranges are a 9V PP3(6F22), and one C cell, although an AA will fit to get you away.


I was excited like a little boy with a new toy to get the back cover open to give it a good looking over. Turning it upside down onto its face, are 4 sturdy anodised screws that are covered over by plastic plugs in each corner of the case, these easily pop out with small screwdriver forcing them up.

The rear cover then splits away in half, leaving the wires attached from the battery box to the main PCB. I was slightly disappointed by its SMT design, but I accept most things are done this way these days. The odd leaded capacitor and resistor tagged onto the rear of the board did remind me of designs of past years, switching is direct onto the gold plating onto the board. The PCB looks good, there were no signs of any dry joints, however I could not see any fuses for protection, nothing is highlighted in the schematic, what could one really expect for the money? Perhaps I am just used  to my ageing AVO 8 with its popout safety breaker.



If you note from the specification the meter does cover 2.5KV! However, I would certainly not like to be on the end of it with the test probes provided (two pairs included), my BIC biro has more plastic on its case than these suicidal leads that are certainly not up to the job!  A purchase of a good pair of leads to CAT III spec is a must!




Conclusion so far:  Sturdy well made case, Meter movement has the looks and feel of a professional movement costing 10 times more. If you are a novice coming into the hobby and you can't read Chinese don't blame me if you can't understand the manual how to drive it? Anyone else who has been part of the hobby game or the field should have no problem sorting it out. May not be serviceable if you blow or damage parts on the board if you select and use it on the wrong range? Requires a decent set of test leads and probes!   

Testing to be concluded further down the Blog.