SOTA Chaser/Activator name sheet and log.

How often have you forgotton a name during a heavy pile up of chasers?  Well for me it happens often,  most liklely old age setting in I guess! Of course there are always the regular chasers and friends one remembers instantly, however sometimes there are those callsigns you just can’t put a name to. Maybe it’s  a new or upgraded call or in the heat of the moment we forget who knows!  Some would say “so what, just ask their name during the contact” True, however I find  the pile up’s and the rhythm of the Summit activation tend to flow smoothly when you know the persons name. It becomes more personal for the contact too.  Obviously I needed a solution to aid my memory, so I just compiled a list of names and callsigns from my activation log sheets. Ok job done, so now I need to record this information for quick recall. I thought of using an electronic device such as an ipad or a tablet maybe the phone. All good but now I would need to carry yet another piece of equipment to the summit and then try to use it whilst operating the radio equipment. Now we are talking about trying to do more than one task simultaniously. Hmmm, my usual operating position balancing the radio on a log or rock, sitting on the ground with a log sheet and clip board trying to write information whilst avoiding march flies and large ants is enough to do!  Ahh its time for some old school technology, enter the good old  double sided laminated name sheet.


As you can see from the images, the SOTA name sheet is just a word document with some tables inserted. (Note: Not all Australian Chasers/Activators are on this list only the ones I have logged) I find the sheet handy for recalling names instantly and easier than trying to operate an additional electronic device during an activation. I also included the recommended Australian SOTA operating frequencies.  The sheet will require updating when new contacts with chasers or activators are made . I often place an astrik in my activator log sheet next to a new contact, then update the SOTA name sheet when I enter the data for the activation, otherwise I write on the SOTA name sheet with a sharpie pen then update the word document, printing and laminating when the need arises.  The SOTA name sheet has been developed for Australian call areas however it could be adapted for other countries or call areas. The file is included here in .doc and .docx format should you wish to modify it for you own use.

SOTA Name Sheet040116 .docx

SOTA Name Sheet040116

Whilst I was making a SOTA name sheet, I decided to make a log sheet too. I managed to fit upto 30 contacts on the sheet, yes I know I’m old school but I do find it easier to write things down when trying to activate a summit.


I am interested in any suggested modifications or  improvements you may have, please feel free to download the documents and make changes as required.

Cheers: Rob

Batteries for portable use.

Batteries for portable radio operation are always an interesting subject for discussion. I have been asked many times which batteries I use. My battery of choice for portable operation is the LiPo (Lithium-ion polymer ) battery.


I find the 4 cell 5 Amp variety suits my situation very well. The operating voltage can be up to 16.5 volts with no load when fully charged. However the stated nominal operating voltage is 14.8V   Most operators would be concerned  these voltages may cause damage to sensitive 13.8v radio equipment. This is correct in some circumstances.  I operate a Yaesu Ft-857 for  SOTA activations, this is a radio designed for in vehicle operation where voltages may exceed 14.5v. The specifications for the FT-857 state the normal supply voltage is 13.8v +/- 15%. This equates to an operating voltage range of  11.73-15.87V. Even better for the FT-817 being specified at 8-16volts . Ok so I hear you say ” Your  16.5v battery is outside that range!” This is true, however by making use of a full wave bridge rectifier in circuit (I use a MDA3504, 35Amp 400piv variety) the voltage will be lowered by 1.2-1.4v. (remember silicon junction theory 101) There are two advantages, a lower voltage and polarity protection. Ensure you  wire the rectifier correctly in circuit, the Battery  wires are  connected to the “AC” input terminals on the rectifier, Do not be concerned  which battery wire connect to what “AC” terminal it makes no difference. However it is critical  the Radio positive (RED) wire is connected to the + (positive) terminal of the rectifier and the Radio negative (BLACK) wire is connected to the – (negative) terminal of the rectifier. I recommend using an in line fuse between the rectifier and radio for protection.   Once the bridge rectifier is in circuit the no load voltage is  15.1V  from a fully charged LiPo battery.  There are some heat losses via the rectifier however mine is mounted on a small heatsink and becomes luke warm  at 100w output on SSB. I would not recommend a full duty cycle mode such as SSTV or FM for long periods at this output level.


How long does this battery last on the FT-857?  That depends on what output power is used. For my  SOTA activations I set the output to 30% , (approximately 30w) at this level I have successfully activated 3 summits of about 20 contacts each and still had plenty of power left. There are precautions with LiPo batteries, they can be easily damaged by incorrect charging and balancing. They have also been known to catch fire under certain circumstances. I have not experienced any such issues with the batteries I use, however I follow the documented procedures for this type of battery. It is always a good idea to monitor the individual cell and combined voltage when using the battery. There are many voltage monitoring devices available for purchase, I use a fairly simple unit which emits a loud screech when the cell voltage reaches a pre set level. Mine is set to sound the warning when any cell reaches 3.5Volts.


 This setting will ensure the alarm sounds when the battery reaches less than 14 volts. The limit can be set lower, however I prefer to err on the side of caution maintaining the battery condition  since replacement cost is not cheap. There are several brands and styles of LiPo battery available, I use the Turnigy  brand,  they have a very good reputation especially with the Radio Control crowd. I prefer to use the hard case variety, they are a little more robust out in the field. There are lower voltage (12.3v) 3 cell LiPo batteries available for those who want to connect directly to the radio equipment. Hobbyking is a good source for these batteries. I tend to avoid ebay as a source of cheap batteries, usually these batteries are cheap because they are  older stock and have not been  regularly charged so have degraded over time. Dealers who have a high turnover of stock do not have this problem.


 As can be seen here the battery voltage indicated is 16.4v and the display on the radio is 14.9v after the rectifier. Transmitting at full power (100w)  reduces the voltage to 13.2v on peaks. The LiPo battery is able to provide bursts of high current when required, in some cases up to 30 times the charge current to 150A. Charging can be easily managed with the many charges available on line. The charger I use allows an input voltage of 13.8volt perfectly suited to charging batteries whilst driving between SOTA summits.



Radio operating at full power with 13.2volts indicated. The battery recovers quickly after transmitting making it ideal for portable operation. In comparison to Sealed lead Acid batteries the LiPo battery is about quarter the weight for the same current, perfect for lugging to the top of summits! As always ensure you read the instructions and follow the precautions for using LiPo batteries with your equipment.



There comes a time after climbing some tough summits when you decide to look at the weight of your backpack. I had  recently walked 20Km to activate a summit in the Snowy Mountains, towards the end of the walk my backpack just felt too heavy. I had stopped on several occasions to rest and I remember thinking “I have to lighten this pack!” The radio I use for SOTA activations is a Yaesu FT-857, it weighs in at 2.5Kg. A great radio which covers all bands and produces 100w output. I also have a Yaesu FT-817, by comparison it weighs only 900 grams without battery pack. I hardly ever take this radio on SOTA activations since I prefer to run about 30watts output and the 817 is lucky to produce 5 watts! I had thought about building a lightweight amplifier to boost the output of the 817 to around 30watts. I looked for suitable components on ebay and this is where I discovered the MX-P50M amplifier. It was advertised specifically to suit the FT 817  and produce an output of 50 watts at a mere 500grams.  My first thoughts were, “this might be one of those dodgy cheap amps, best to be avoided !” With that I decided to move on and continue looking for parts to build my own amp. I found many parts and kits available to build a small amplifier however I was curious about the little amp I had seen. I decided to do a Google search on the amplifier, I found only one positive report on eham and no other information, no circuits nor operation manual. For the asking price ($226 delivered) I decided to purchase a unit, thinking if it did turn out to be dodgy, I would simply use the components to construct a better amp. It took only a week for the amp to arrive from China. The amp ships with a DC cable, an FT-817 control cable and nothing else. No instructions, specifications or circuit!


Setting up the amp is relative easy, simply connect the supplied control cable to the FT-817 accessory connector and the DC cable to a 13.8v supply. Then connect the coax output from the radio to the input of the amp. The output of the amp connects to your antenna.  The amp has a manual band change switch, so check the band switch is set to the correct position before transmitting.  Not having any specifications, I had no idea what power level could be expected. I connected a power meter and dummy load in line and decided to test initially on 40M.


Applying 3 watts AM carrier from the FT-817 produced 30Watts indicated on the meter.


On SSB a whistle into the mic produced 50watts indicated. So far so good, I proceeded to try the other bands and was delighted to find I could produce 45watts PEP at 28.5 Mhz and 50 Watts PEP on 3.585Mhz, Note the voltage reading of 13.3v.


Here you can see the full output from the FT-817 producing a healthy 50watts PEP on the 30M band. I conducted tests at a higher input voltage (14.5v) and found the amp can produce more power output if required. I did find some specifications for the encapsulated  RF device inside the amplifier stating it can accept input voltages up to 24v to produce 100w output. I am not going to try it, the results could be catastrophic!


The MRF 186 encapsulated RF device as used it the amplifier. Also an internal view of the amp, showing the filter layout and circuit arrangement.


Having tested the amplifier into a dummy load it was time to put the amp “on the air” I started with 40Metres and called CQ with 5 watts only. Vin, VK3FMOL replied and reported a 5×4 signal received at his location. I asked Vin to check my signal strength again this time with the amp on line. My signal report was now 5×8, but more importantly Vin said my audio level had increased quite a lot to the point where I was readable above the noise.  At that point Scott VK7NWT broke in to provide his report. He had been listening and was happy to report the same, an increase from S4 to S9 with a large increase in received audio level. Scott also reported he had tuned across my signal whilst I had been talking with Vin and could find no evidence of splatter or bleed over, thanks Scott. Seems like this test had a few people interested because Ray VK3NBL was next to call in and report he had no particular signal increase but a noticeable audio level increase. Ray had also been looking at one of these amps, but like me was dubious about the quality. As it turns out I had contacts with four or five others whilst using the amp and all the reports were similar, a noticeable increase in audio level and no change in quality with some reporting a signal strength increase also. During the tests I noted the amplifier remained cool to the touch and the current drain was around 6.5 amps on voice peaks.  I have been asked several times if this amplifier can be used with radios other than the FT-817. The answer is yes provided you can supply the correct RX/TX control lines into the amplifier. The amplifier is supplied with a connecting lead and attached plug suited for direct connection to the FT-817 Accessory socket. I have taken the time to check which connections are made to the FT-817 and they are as follows. The Black or in some cases Blue control wire from the amplifier is connected to ground or GND (-VE)  on the radio and the Red control wire from the amplifier is connected to TX GND from the radio. So to operate the amplifier in transmit mode it is a simple matter of shorting the two control wires from the amplifier together when transmitting and open circuit them when receiving.

Some people have asked if there is a way to use the FT-817 CAT control and the connection for the linear amplifier simultaneously. Well in fact one of those people was John Schultz who not only asked the question but provided the answer via a file he found on the net from a SK Charles Socci K1DNR. I have provided that file for download here:simultaneous-use-of-cat-control-and-linear-amplifier-on-yaesu-ft-857d Thanks John for sending me the file and thanks to Charley K1DNR.

Recently my amplifier destroyed the in line fuse every time it was connected to the DC supply. A quick investigation revealed there is an 18v Zener diode used as a form of protection circuit. This diode had gone short circuit causing the fuse to blow. I replaced the Zener with a suitable type and have not had any problems since. There was no apparent reason the the diode to become faulty, unless I inadvertently reversed the DC connection polarity. Maybe I had a seniors moment hi hi!

 In conclusion I can recommend this amplifier to anyone looking to boost their FT-817  output to around 40 watts. I will continue to run  30 watts as usual. For me this amplifier will now accompany the FT-817 on my future SOTA activations. My FT-857 will be installed in the vehicle which will lighten the backpack by 1.1Kg. A good saving!