20082017 – VK3/VC-018 Mt Bunnyiong
VK1 SOTA activation day and a test run for miniHFPA HF Packer Amp.
Noticed the alerts going up for VK1 2017 Winter SOTA Party so decided to go to local summit to play SOTA one what looked like a reasonable day to go out. Propagation recently has been terrible for NVIS so decided it was time to test my newest toy, a miniHFPA HF Packer Amp. This is a 35 watt linear amplifier designed for portable operations.
Decided to a to build a lightweight amplifier that can be backpacked to sites and be powered by a light weight LIPO 3S battery. Did look at commercial options. There are several out there a assembled Chinese unit and there are several kits available from eBay but appeared not to have adequate filters and lacking harmonic suppression. Glenn VK3YY describes building a unit based on W6JLs designs. There are a lot of kits around which would be more accurately described as harmonic generators.
I went for the HF Packer kit. I have decided to build as much as I can and not being a electronics engineer more that happy to assemble kits. The new 35w kit was announced and I put my name down for a unit. Not the cheapest options but was expecting a unit that was well designed and meet the conditions of my licence
The build went well. The biggest issue I had was using unleaded solder. My fixed temp iron was not hot enough. A new variable iron fixed the issue and the build progressed. Once completed had issues completing the testing process. The issue came down to incorrect marking of the RF ports. Once addressed (Thanks David) the device leapt into action.
So going from 5w to 35w output is a gain of 8.45dB. Given 6dB is a S point expecting an additional 2 sS points for my signal reports. VK7CW and VK2YW gave me a 599 with the amp in use.Off top a great start. Later without the amp in use I received a 559 from VK2WP. None of the contacts were soliciting reports as my CW is only good for making contacts not setting up experiments. Pre roll over SSB contact with VK1CT received 59 and post received 45. No one described poor signal so very happy with results.
At 717grams it won’t be a frequent addition to SOTA activations but when conditions are not good and the trek supports the additional unit and battery 35W it will be available.
The 4500mAh 3S 30C LIPO was at 80% after hour of use. Time for new batteries so will be going for a 2500/3000 mAh unit.
So the next is to develop a suitable antenna. Used a trapped 20/40 unit based on SOTABeams 100w traps for this activation.This unit is too heavy for SOTA however so looking at options.The AMP is rated at 35W for 60/40 & 30/20m bands. Will need a resonate antenna to avoid carrying a tuner so looking at a EFHW (End Fed Half Wave) instance. There is a lot of information out there. David VK3IL page describes a similar quest he went on and a search of the SOTA forum search pointed me towards HB9TVK. Thinking of using T80-6 for traps and a T140-43 for the matching transformer, RG178 coax and lightweight wire. Yes looking at grams here and the trap weight has to be trimmed else the wire will sag too much and can’t be seen on a summit with a sagging antenna!
More on antenna as options are finalised. Also will be building a CW radio for wet harsh conditions. Ordered the QRP-Labs single-band 5W CW transceiver kit and will build into a waterproof case.