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I tried a little backpack DATV portable yesterday, with what I thought was very minimal equipment. The thing is it still weighed a ton, so how do you guys that do SOTA and alike keep the weight down ?
My Portsdown in the pelican style case has 6x18650 in so that has its own power, but my 23cm PA would soon drain this so I use a 19ah SLA battery. The mast at present is some old steal tent poles so could change these to aluminium or fibreglass I suppose?
The other thing is PA power, just how little would be practical with DATV? Not looking to smash DX records, but hopefully take advantage of high spots not reachable be car portable. Not that there are many here on the South coast, but thinking ahead when holidays are next being planned it may be worth looking at the terrain first
All best and stay safe John G7JTT
All best John
Some random jottings follow. After over 220 SOTA activation and becoming a SOTA mountain goat , I can say that it's about pack weight. Mine has been around 28 lb constantly. I play a trade off between weather conditions, how high and how far against radio hobby equipment. 1 pointer in Shropshire would permit a FT857D, LiPo batteries and a lot of wire antenna with less stuff for taking care of me. An 8 pointer in the Lake District or North Wales needs more clothing, drinks and food so there's room for a handheld and 2m dipole. Line of sight from 800m ASL is rather good.
There's no ATV category in SOTA as far as I know. Perhaps the club could ask the management team at SOTA nicely for one? Our clubmates in Cumbria have done 6cm FM ATV on SOTA summits and managed a summit 2 summit. All on 1 pointer summits. Well done there.
You're going to need a barrow, hand cart or mountain bike with panniers for the kind of mass that you're using. An ex-infantry soldier would do. All great until the first stile or tight gate! We wish an activator a safe descent because we know how vulnerable are ankles. I've some horrid injuries from 2009 on Moel y Golfa so know this first hand. Is 70cm the sweet spot for DATV in terms of amplifier power and mass ? One of those amp kits off Ali Express that have no instructions might do if Jim G7NTG has worked out what to do? One of my 70cm beams is from B&Q - stockists of 25mm electrical plastic conduit, aluminium rod and tube and PVC tube (dipole centre). It splits in two with a sleeve joint. 22mm wastewater pipe fits inside 25mm conduit. About 200 grams too. My 2m and 23cm beams are B and Q too.
When I attempt SOTA DATV I am going with my activation partner Alastair M0TYM who does a good impersonation of a Sherpa. He once carried 2 SLABs up Aran Fawddwy and only found out at the top. We didn’t use the batteries nor the HF radio cos it was bloody awful weather. I fancy trying to activate tv on Cadair Berwyn after many smaller hills practice. Pipe dreams.
Ray M0DHP does SOTA and DATV - separately - on the South Downs so might be a handy collaborator. Butser hill to Chactonbury Ring S2S?
This is a tricky challenge. Well done so far.
All best John
Battery power - battery tech has moved on a lot from SLAs - the RC flyers hobby has spawned some very good LiPo batteries (like anything, understand what you are doing and all will be well). For current draw and light weight they can't be beaten. Due to the massive market, they are cheap too.
LiFePo are a 'less fussy' alternative, still offering great power density and increasingly popular for golf carts and mobility scooters. (£££'s though).
Big laptop packs I investigated for SOTA use via airline travel - you are limited to under 100W/hr packs and rather than be faced with 'you can't take that with you Sir' I checked the CAA rules about what you can take. OEM laptop batteries are not things that look like bombs. I found info on how to 'turn on' the packs online, built a connector and tested a couple of 98W/Hr toshiba packs. They will tolerate up to a 8 amp draw and delivered over 7.5A/Hr at lower draws. Recharge from a RC 'all-types' charger seems to work well. This pack would power a small amp and portsdown for a good time.
I built some fishing pole yagis for 2m - 6 element at 5m AGL. It worked well so I moved on to a 12 element ZL special, based on a 10m fishing pole. All lightweight and backpackable and LOTS of gain. A similar solution for 70cms would also be entirely possible, its on my 'to-do' list.
Given how full-feature a Portsdown is, adding just a Picam and a Lime mini with a 70cms brick amp (in a recent CQTV) and a beam is should be possible, with care it probably weighs less than a FT817. The MRF100 datasheets/AN's shows a really minimal board design for a 144 MHz amp and other than needing a step-up from 12-50V would easily reach / exceed DATV ERP limits with a small beam. Also on my to-do list.
Comments re ankle noted - I took a lot of this gear on holiday to Lanzarote Dec 2018 with my son, who went to cycle. As I walked up an unactivated volcanic cone, on my own, I was thinking....this really isn't a good idea....so I was VERY careful. Got to the summit, set up, worked nobody on 20m, but all the kit worked as planned.
Pictures and more info if anyone is remotely interested - message me and we can progress to email so I don't have to resize the pictures....