A QRP Technique using the 41 db Attenuator

 Have you ever noticed that when it comes to QRP (or whatever), you turn on the radio, scan the frequencies and if happy with what your hearing, you tune up for the lowest SWR and whatever power output you want (1 watt, 5 watts, 100 watts or whatever) and then you begin tapping out "CQ". Sound familiar? If a station is booming through (599), then naturally you go off frequency, dial the power down, go back on frequency and answer him. 

The problem I found with this procedure is that when he reply's, even at 1 watt he gives you a 559 report. This means that in reality, you you could have gone even lower in your power. 

Well, I got to reading a blog by Bert (PA1B) where he does the opposite. He actually starts out at the lowest power level and then works up.
You can read his blog HERE or his web page HERE

Its interesting because it got me thinking about the way I've been doing things. Yes, I had a 41db attenuator, but was I using it to its full potential? Hmmm.. maybe not.

If you read thru Bert's blog and web page, you'll see how it works, what he does and what he has achieved. So after reading thru his web page and blog, I decided to give his method a go. In other words, start with low power and work up.

Here's what I do now.

I'll power up to 5 watts and tune in with the ATU on whatever frequency. Then using my 41db Attenuator, I'll go down to 250mW and call out "CQ" a few times. If no answer, I'll double my power (3 db) to 500mW and call out "CQ" a few times. If no answer, I'll double my power again (another 3db or 6db in total) and repeat. I'll keep doing this till someone answers. 

Now if I get no response and I'm now at 5 watts, I'll change frequency, for example 10m down to 15m and repeat.

Does it work? Yes ! See my last post with my QRPp contact with Mike (ZL1HJ) down in New Zealand on 500mW and Max (VK2ARZ) with 1 watt in New South Wales. In both occasions, I only called out twice and they both came back straight away. 

Anyway.. something to think about when going QRP.
You never know just how far you can get when you drop your power

# 11- 1000 MPW Award ... 2172 MPW @1/2 Watt

After working 10m for around 1/2 hour with no luck, I decided to come down to 15m and try it there. Scanning around, there wan't much activity around, but I decided to start out at QRPp levels and work up. You just don't know who may be scanning around as well. 

Cranking up 500mW I called out "CQ" and Max (VK2ARZ) came straight back. We've spoken before, that was a while ago now. However, it was great to have a quick 500mW QSO with Max from Mortdale Heights, down in New South Wales, Australia. 

Unfortunately at the time I had to cut it short as it was time to go to the beach for a nice cup of tea. All in all it was great to get talk with Max again.  At 1/2 watt, that works out to 2172 MPW, enabling me to get my 10th 1000 MPW award. 

Thanks Max and 73's mate

After the contact, it was time to fire up the firebox and boil the billy for a nice cup of tea. If the tide was a bit higher, I'd be flicking a lure chasing a Barramundi for dinner as well.

Oh well ... The cuppa was sweet as... hmmm

My 10th 1000 MPW award

#10 - 1000 MPW Award... 2349 MPW @ 950 mW

 

My new personal 15m MPW Record.. 2349 MPW

It was great to have a quick 950mW QSO with Mick (ZL1HJ) from Te Kuitin, down in New Zealand (North Island). 

At the time I was trying out a new idea with my Attenuator at QRPp levels, where I start out at QRPp levels and then slowly work up to 5 watts if no response. Today I decided to start out at 500mW and after a couple of call outs, I turned up my power to 950mW.

After calling out twice, Mick came back and gave me a 559 report. Propagation at the time was going up and down like a yo-yo, so we had to keep it brief.  Turns out he's also a SKCC and FISTS member. 

After a quick chat, the band began to drop out..FAST, till we lost each other in the noise. After about 30 seconds, it returned in strength, so we quickly said our best wishes and 73's and called it a day. 

All in all it was great to get the contact.  At 1 watt, that works out to 2349 MPW, enabling me to get my 9th 1000 MPW award. 

Thanks Mick and 73's mate

Building my Homebrew DX Commander (10/15/20 & 40m bands)

 G'day all,
Its been a while since I've posted, but I decided to: 

1/ Move my antenna system from the backyard to the front yard. The reason being, with all the tall palms/ bamboo and then all the sheds we have, this is all going to effect the antenna. Whereas is the front yard, it had a clear view to the ocean with no obstructions.
2/ Design a whole new antenna. In other words, get back to basics. (verticals/ dipoles or random wire) 
3/ Get up to speed using my new paddle (never used one before) 

Being that I already had a 10m squid pole, I looked around the net looking at various types of verticals, one of which was the DX commander. After a bit of research, I doing a bit of number crunching, I decided to model a 3 element version in EZNEC (antenna modeling program)  to see how the elements interact with each other (if at all) and also to see what the RF patterns would be like compared to a typical 1/4 wavelength vertical. After a bit of pushing and pulling the antenna, I was finally happy with the output. I then I modeled the antenna in AutoCAD, designing the parts to print out and then construction began.

First thing was the spreader plates which I made from some chopping board (HDPE) material from the
 $2 store. 

Next was the ground and element plate. I had an old 3mm aluminium BBQ cover plate tucked away in the corner of the shed, so I grabbed this. Bit scruffy, but after making it I polished it to bring it back to new.

I then dry fitted it all together

In the picture below, you can see on the table another ground plate. This plate I discarded because when I was bending the tongue, it was a bit to close to the element plate. Easier to make another one

My wire arrived from Jarcar, so time to duck down to the hardware store for some SS nuts & bolts, electrical forks, SS clamps and hose and some PVC pipe. Time to put it together

Here I took out the insert of the base cap and found that 40mm PVC pipe fitted perfectly inside the lower tube. So I cut a section of pipe 300mm or 1 ft long and inserted it

Next I had some 50mm PVC pipe, so I bought a cap to fit, marked the centre of the cap and then drilled and dremeled out a 40mm hole. I cut the pipe so that it was 300mm long, ground a chamfer on one end and pushed this into the dirt where I wanted the antenna to be. 

 Time to stand the antenna up for a dry run. Here you can see the antenna cap is now sitting on the PVC cap and with the 40mm pipe inserted into the pole itself and also the 50mm, this antenna base is rock solid and going nowhere

Initially I only used the lower guys to steady the pole and I knew I would be dropping it down again and again with tuning the elements. 

End SWR result:

40m = 1:1

20m = 1.3:1

15m = 1:1

10m = 1:1

I'll just use the ATU to bring 20m down to 1:1

Radials... 9 bundles (4 radials per bundle) = 36 radials in total. Each radial is 10ft-7" ( 3.22m) long

Then it was time to drop it down again, install the upper guy lines and stand it back up. Rock solid in 25 kts winds. Just have to wait for my shock cord to arrive then its finished. 

Total cost to build?

$112 

So overall I was pretty happy with it. Later that day I cranked up 20m and made contact with Mark (VK3MJ) 1377 miles away on 5 watts (579 report) and a day later on 1/2 watt. Trying the rest of the bands on 5 watts I watched the RBN to see if I was getting spotted and saw that the USA/ Canada/ Europe and others were getting my signal. 

All in all.. very happy with the result. 

Catch you on the bands !