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FT - 857 battery power and 80M SOTA


Right I have an FT - 857 which I use at home in the shack, and I can’t really afford to get an 817 at the moment. Any suggestions on how to power the 857 on the summits? Batteries but what type and where from?

80M Sota. Thinking of doing some 80M activations if I can get the 857 working on the summits, on SSB, would a dipole do for this?

Many thanks from a newish SOTA operator.


In reply to M6CSS:


I also use an FT-857 as do many other activators so there is a lot of information on using them on batteries on the reflector. If you search, I’m sure you’ll find all the old threads.


  1. SLA. Heavy but you may already have one. Voltage droops in use limiting energy recovery.
  2. NiMH. I use 11 cell packs which give just the right voltage.
  3. LiFePO4. More expensive but very light and forgiving. Ideal voltage.
  4. LiPo. 3S pack is a bit marginal (low V). 4S is a bit high. Common practice is to use the Vf of a diode to lose some voltage from a charged 4S pack.

If you have Edition 10 of the RSGB Handbook, I’ve put quite a lot of info on batteries in there.

What size?
50W SSB for 30 mins needs about 2ah. That’s all.

GL. I hope you get as much enjoyment from SOTA as I have. Work you soon. Your name?

73, Richard


In reply to G4ERP:
I use Lipo 3S with the FT817, lipo batteries are ideal for sota, nice and lightweight which is key for long climbs. As richard has stated there are many articles here, i have posted a link on one of them to where i bought the batteries and charger i use.



In reply to M6CSS:
Hello Karl I used FT857 for 1 year on the SOTA. It is good radio but rather heavy and with more consumption. I powered it from 7 Ah SLAB. It were about 1 hour of the work, when I used 10W in CW. I thing better is to use LIPO battery. The same capacity is lower weight and dimensions.
If you prefer to work on the 1 band only, the best solution is dipole probably. You will need no ATU. If you prefer to work on the more bands, you can use any simple antenna like LW, G5RV, but you will need to use suitable ATU. I am looking for to meet you soon.
Jirka OK1DDQ


In reply to M6CSS:

Hi Karl - I use ft857 with 7AH deep discharge sealed lead acid batteries (SLABs. I got mine via the internet from Rapid Electronics. They are good for full power ssb for at least an hour, so at 10w should give twice that time. You can use non "deep discharge" batteries, but at full power (22amps) you may damage the battery plates - this shoulnt happen at lower powers. I will eventually change to lipo or life-po technology when my slabs start to die on me. (SLAB`s are better for building up the calf muscles hi)
ps dipole is fine for 80m, however in the summer daylight hours 80m tends to get absorbed by the D layer, whereas at night or throughout the winter is is a great band.


In reply to M6CSS:

Hi Karl,

I used to power my FT-817 from SLABs and progressed to 3 cell LiPos when the price came down. I therefore had the LiPOs on hand when I progressed to a FT-857. While this worked, after half an hour or so at 25 watts the modulation started to get rough. Not wanting to purchase another set of 4 cell LiPos just for the 857, I decided to add a large capacity NiMH cell to each of my 3 cell LiPos to bring the voltage in line with what the 857 requires. This arrangement works out very well and can be used for both the 817 and 857 as I have taken an output which puts just the LiPo in circuit.

see - http://www.flickr.com/photos/18897403@N00/4491202158/in/pool-sota

Starting from scratch, my recommendation would be to get 4 cell LiPos and use a diode dropper with a shorting wire to take the diode out of circuit when the battery volts drop. As has been mentioned, this subject has been covered on this reflector in the past.

73, Gerald


In reply to M6CSS: Hi Karl.
I use a 857 with 2 x 7 Ah SLAB. With 20 W on CW and 30 W on SSB.
Is about 2 - 3 hours work perfectly.
I use a 3 band dipole 7/10/14 on my 10 meters high fishing rod + MFJ 945E.

I hoope to hear you on Karl.