https://www.facebook.com/370878076655074/

Vk2ijm, Berowra (2026)

30/03/2025

For the past few weeks I've been slowly building a 1KW pallet amp for HF/6M in my spare time.

1KW HF/6m -amplifiers generally cost upwards of 4K, so the pallet amps can be a cost effective alternative, coming in at ~ $2k.

My parts list and construction tips as follows:
- Pallet amp board using 4 x MRF300 LDMOS devices from VK3AMP. I chose VK3AMP because they provide a ready-built board mounted on a copper spreader (needed for 1KW) for around $850. Anyone that has tried to purchase the copper separately and do a DIY job will know why its vastly easier to purchase the ready made board and vastly cheaper unless you have the tools for this job.
https://www.vk-amps.com/products/a-1000w-ldmos-linear-amplifier-50v-1-8-60mhz-4-x-mrf300-pallet?fbclid=IwAR0FMVp12oD_QHDcFF9lPnUbH2RBeu9RsPxUion357Ab9wTexzr2tvrRGns

- For the LPF and TX/RX switch, I went with DXworld-e as they are slightly cheaper. (205 and 29 Euros resp) I would recommend using the TX/RX switch as it can switch the bias on / off with the PTT control and it also supports two antenna ports. The LFP units come in 5 & 7 pole varieties and I purchased the 5 pole option as it's a bit cheaper. However the 7pole filter does offer 10db better rejection of harmonics. Both options provide 7 bands from 160m to 6m. You can find cheaper boards on ALI express (~$120) but I went with something that was a bit more tried and proven.
https://www.dxworld-e.com/product-page/hf-lpf-filters-160-6m-1500w
https://www.dxworld-e.com/product-page/rx-tx-antenna-switching-1-80mhz-1500w

And the heatsink is an important consideration. I purchased one from DXworld-e with the other parts @ 38 Euros
https://www.dxworld-e.com/product-page/heatsink-dx-20

The PSU unit was an ALI express purchase and delivers 33A with adjustable voltage up to 60VDC - Cost was $191. You can also buy these from VK3AMP for a similar price.
https://vi.aliexpress.com/item/1005004661730742.html?src=google&pdp_npi=4%40dis%21AUD%21233.87%21168.19%21%21%21%21%21%40%2112000030019382504%21ppc%21%21%21&src=google&albch=shopping&acnt=742-864-1166&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&gclsrc=aw.ds&albagn=888888&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005004661730742&ds_e_product_merchant_id=107571896&ds_e_product_country=AU&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=21819463808&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gclid=EAIaIQobChMIzJiZzrqxjAMV5NEWBR27dyGmEAQYBiABEgKmmfD_BwE&gatewayAdapt=glo2vnm.

The case was a 3U rack mount server case from JAYCAR, cost $149. This case has 2 rails for use with spacers, which I used in my construction. see attached pictures
https://www.jaycar.com.au/3-unit-pro-grade-19inch-rack-style-equipment-enclosure-flatpack/p/HB5130?srsltid=AfmBOoofNgoSg4h7Fwq0EyhwDNIhg1EdK-KyCtaQsjjvsd2yM8bJ66l_

You might also need an attenuator pad depending on your rig's minimum power setting. I purchased a 10db 50W pad as my FTDX has a minimum power setting of 5W. If your rig outputs down to 1 watt you can possibly skip this option, but I would advise to include this to protect the LDMOS devices from the ALC spikes that will eventually degrade the LDMOS.
https://vi.aliexpress.com/item/1005006844994941.html?spm=a2g0o.detail.pcDetailTopMoreOtherSeller.1.1736XvnxXvnxuJ&gps-id=pcDetailTopMoreOtherSeller&scm=1007.14452.396806.0&scm_id=1007.14452.396806.0&scm-url=1007.14452.396806.0&pvid=b060b224-f30d-4dac-8bd1-ec64558915a9&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.14452.396806.0,pvid:b060b224-f30d-4dac-8bd1-ec64558915a9,tpp_buckets:668%232846%238107%231934&pdp_ext_f=%7B%22order%22%3A%2210%22%2C%22eval%22%3A%221%22%2C%22sceneId%22%3A%2230050%22%7D&pdp_npi=4%40dis%21AUD%2173.83%2147.99%21%21%2145.78%2129.76%21%402101eab017433265604243641e73b8%2112000038493540091%21rec%21AU%212864121186%21X&utparam-url=scene%3ApcDetailTopMoreOtherSeller%7Cquery_from%3A&search_p4p_id=202503300222404593780399801709850320_0

High power needs cooling. I mounted 3 quite mag-lev fans, 2 underneath the heatsink sucking from outside and blowing u onto the heatsink and one pushing air out - I used a separate voltage regulator cct inside my amp to reduce the voltage / fan speed to an acceptable audible level as the quiet fans are still making a air sound.
https://vi.aliexpress.com/item/1005008358097680.html?src=google&pdp_npi=4%40dis%21AUD%2111.27%2111.19%21%21%21%21%21%40%2112000044710684392%21ppc%21%21%21&src=google&albch=shopping&acnt=742-864-1166&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&gclsrc=aw.ds&albagn=888888&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005008358097680&ds_e_product_merchant_id=107678322&ds_e_product_country=AU&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=21819463808&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1&gclid=EAIaIQobChMI5cKSgsCxjAMVz-sWBR1xzicMEAQYBiABEgK2FPD_BwE&gatewayAdapt=glo2vnm

Any you'll need a variety of other parts, such as SO239 chassis connectors, RG316 coax, SMA connector / cable, power switches and toggle switches, not included here. I used my shack collection of parts to cover most of these.

For the band switch, you can purchase a single pole 7 position rotary switch or in my case I am only using 2 bands and use a 3 position switch for 6m and 10m and auto. I'm going to purchase the linear amp connection cable for the rig and make up a cct to automatically switch the LPF based on the band data and have 7 LEDS on the front panel to show the band setting. You should also add a voltage and current meter and overload protection and I'm still waiting for these parts at the time of writing this post and will update this post later.

For bias setting, turn the 4 pots anti-clockwise and connect your 12V bias source and have your current meter on the 50V feed. Adjust each pot clockwise to add 250mA of bias current until all 4 are done adding up to 1A in total. You might need to do a few turns before you see any effect on the meter.

Upon testing, everything worked first go and the amp puts out 900W with 5W input. With the 10db pad you need 45W in for max output.

21/01/2025

Drone image of Berowra with views to the mouth of the Hawkesbury

20/01/2025

With the fires raging in the USA I though it would be worth noting the amount of natural bushland in Sydney's north. These images are taken from above my house in Berowra using a DJI mini 4k drone and there is bush as far as the eye can see in every direction.

25/11/2024

I though I would share my shack UPS project as it's been a while since I added a post. The UPS uses a stack of Sungrow batteries and a Sungrow hybrid inverter. The storage capacity is 22.4KW/h, so it should be able to power the shack for at least 12 hours during an extended outage. The battery is charged by an array of 10KW of solar panels which can generate up to 70KW/h on a good day in December and down to 32KW/h on a good day in June. The system has 7 x 3.2KW modules installed with space for one more module in the stack.

I've added a rain / shade hood as the components are installed outside the house and it's important to keep the batteries out of direct sunlight to avoid creating high internal temperatures. Images below are the final install and also a screenshot of the daily usage curve showing battery capacity

Some tips to others looking at buying batteries
- If you have off peak hot water (controlled load), note that net metering doesn't apply to controlled loads, so you'll still pay the same amount for your hot water, but your battery will still offset the same amount back into the grid because it can't tell the difference between controlled load and standard tariff. This is not a wanted outcome, so you'll need to move your hot water to a timer either heat your water during the day when you have excess solar, or move it to after 10pm and decide whether to have the battery offset the difference or whether to turn off discharge for those hours. This decision will be based on your battery size and charge levels and will be a seasonal decision.
- If you want full off grid function when the grid fails - ie: your solar can still charge your batteries during the day, as opposed to your solar shutting down leaving you with whatever charge is remaining in the battery, then you need to have a hybrid inverter connected to your PV array. This is especially important to note if you have existing PV and want to add a battery, because the installers will usually leave your old inverter in situ, even if they add a new hybrid inverter with the battery. In this configuration your old grid tied inverter will still shut down if you lose the grid.
- When a battery is added the install will usually include moving your power ccts to the UPS, but not your lights, hot water, over and stove. If you have a separate fridge cct, you'll want this added as well so make sure they don't overlook this detail.

25/11/2024

Send a message to learn more

15/05/2022

New Remote Site Callsign - VK2JMR

For my remote site on the mid-North Coast of NSW, I've added a new callsign - VK2JMR, which is assigned to my address in that location in the ACMA database. VK2IJM continues on at my Sydney address.

The remote site project has been going for a while now and supports 2m, 6m & 10m, with 2 rigs allocated to the cause. The IC-7300 for 10m and FT-847 for 2m and 6m.

I've been slowly fixing up the shack, which is a modest 4 bedroom house and sits on top of a headland with ocean on 3 sides. The kitchen is almost sorted - some before and after shots below :). Lots of work still ahead as I start on the sanding and painting.

I'm planning on installing an NBS mast in the backyard and will install a separate radio hut / granny flat in the next phase.

10/12/2021

10th December 2021 provided nice E layer activity on VHF in VK region. Whilst beaming Fiji to check conditions on 6m towards Phil, 3D2TS, he also managed to decode my 2m signal @ 3218km. This beats my longest 2m WSPR spot to VK6KXW last December by 26km. I saw Phil's signal coming back by couldn't quite manage the 2-way on 2m WSPR. Phil also saw a few of my FT8 spots but we didn't manage the 2-way contact on FT8, but a 1 way on WSPR and FT8 is still very rare and a first for me. Cheers Phil for setting up for the summer challenge over there and for providing the screen shots from your side.

09/08/2021

With the IPCC releasing the AR6 climate report today, I though I would take a look at the tide gauge nearest my place to see how the SLR has been progressing. Fortunately the Sydney tide gauge is one of the highest quality measurement stations anywhere on earth, being attached to very stable bedrock in a geologically stable zone, thousands of km from the nearest plate boundary over in NZ. I chose the High Tide data from the BOM's website as many people are worried about the high water mark encroaching into urban areas and used the years from 1951 to 2020, these being the decades of human increase in CO2 following WW2, and downloaded these into my excel sheet. The linear trend result was somewhat surprising @ only 0.85mm / year and the last 10 years showed no trend increase. In other words, a Seinfeld story about nothing.

31/05/2021

Inexpensive remote controlled rotator.

For my remote site near Port Macquarie, I was looking for a small rotator to turn the 9el 2m yagi that I could use from my main residence in Sydney and thought I would share the details.

I currently use Teamviewer for remote desktop to access WSJT and change bands etc.

Firstly, the rotator is an RCA brand from the US which costs around USD $120 and includes a small desktop controller.

For remote control I purchased a $22 - USB controlled 8 x relay unit (10A contacts with NO, COM and NC). To get the control unit working with the relays, I opening up the controller and soldered onto the contacts of the control board for L & R buttons and also 2 memory positions. All very simple stuff !!!

And the final component was a $30 camera that looks at the controller, which I use from my mobile phone :)

I have also connected up a similar system in the Sydney shack for when I'm up at the remote site, which taps into the Yaesu rotator controller.

Some pictures below - It's still in the Sydney shack, but will be installed in 2 weeks on my next lawn mowing and garden trimming visit to the remote shack :(

Links to the products:
https://www.ebay.com.au/itm/313452884829?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

https://www.ebay.com.au/itm/353475553397?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

18/04/2021

10m WSPR comparisons - coastal ocean view versus inland hill location.

With my remote coastal station now up and running for a few weeks, I've been able to do some comparisons with my home station. Both stations are using a half wave vertical antenna and have a similar power output of around 10 watts. Unfortunately, both stations suffer from local interference, with the remote station being impacted by a noisy water pump adjacent the small water tower serving the remote community on the headland, but the result is a similar rx interference level compared to my noisy urban location in the northern suburbs of Sydney. Whilst there does appear to be a very slight advantage towards the USA and central Americas from the remote site, the advantage is very small, but what I also found surprising is that the performance in other directions was also quite similar. Overall, the performance of my home station is still slightly better, but this is probably due to the higher antenna height above ground, 17m versus 9m. Although the remote site does have a steeper land-fall away from the antenna. One interesting measurement has been observing the signals between the two stations, 267km apart, with a constant troppo path that varies from ~ -10db to -20db depending on the atmospheric conditions. This is a good distance for 10m ground wave/space wave and my brother VK2DVM @ 330km and 1100m asl in the blue mountains just west of Sydney, can also see my remote site 100% of the time with similar signal results. It would be interesting to see how far the space wave signals can be heard in optimal locations with optimal antenna heights of 25m above ground. My guess is around 500-600 km. I'll be doing some measurements on the 10m ducting path between my 2 stations over the course of the next year.

I've included pictures below of the take-off views towards the USA, including from my home station and noting the path between the two stations..

07/04/2021

Thankfully all is ok up at my remote station (VK2IJM/2) / holiday house, following the big floods. The big clean up is now under way and life is returning to normal for the locals, many of whom suffered significant loss and damage to property. The renovations are progressing well on the remote shack and I've set up my gear in the study / 4th bedroom, in a compact desk arrangement, with the FT-847 and PSU located on the shelf units. I'll add some pictures of the new 2m yagi once it's up, hopefully before the end of the week.

21/03/2021

Big floods in NSW !!!

My remote station (VK2IJM/2) near Dunbogan is ok (I think) - under the red arrow in this picture, however not everyone was so lucky and many houses are inundated with significant water. It will take some time to get power restored to the area and clean up the big silt sludge. I'm hoping to be able to drive up to reconnect the remote site next weekend and also check out any damage to antennas and the house, as we had severe gales with the 900mm of rain (over 5 days).

Vk2ijm

30/03/2025

21/01/2025

20/01/2025

25/11/2024

25/11/2024

15/05/2022

10/12/2021

09/08/2021

31/05/2021

18/04/2021

07/04/2021

21/03/2021

Address

Website

Alerts

Contact The Business

Shortcuts

Share

Category