The FT-897D is a very efficient transceiver for portable use, perhaps because it is designed for use with battery power in mind. As I recently purchased an Icom IC-7200 to replace it for HF use whilst portable, I thought I would do some tests on the efficiency of them both, and also my FTDX1200 for comparison. The IC-7200 is comparable to most other HF desktop transceivers, using up to 20A with a 100W carrier. See the plotted chart below:

Comparing 3 transceivers for efficiency.

Comparing 3 transceivers for efficiency.

This table shows the test results. All tests into a 50Ω dummy load, at 13.8v on 7MHz:

Transceiver RX TX 5w TX 20w TX 50w TX 100w
FT-897D 0.6A 3.8A (9.5%) 6.3A (23%) 9.9A (36.6%) 13.4A (54%)
IC-7200 1.1A 7A (5.2%) 10.3A (14.1%) 14.7A (24.6%) 19.5A (37.1%)
FTDX1200 1.6A 8A (4.5%) 11.2A (12.9%) 15.1A (24%) 19.5A (37.1%)

It can be seen that the IC-7200 is ever so slightly more efficient than the FTDX1200, but neither is anywhere near the efficiency of the FT-897D. It will be interesting to see how the new Yaesu FT-991 compares to the FT-897D! In all cases, the more RF power you use, the more efficiency you are getting ;)

I have a 100AH Leisure Battery which still provides enough power for an afternoons operating with the IC-7200 at full power, so that will do me, although a bit more efficiency is always nice!

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I went out for a little bit of /P operating this afternoon for just over an hour as the weather was OK. Had a nice chat on 40m with some UK stations using the end fed half wave set up as a kind of sloper. The end was up 8m on a fibreglass pole just resting against a tree, and the feed end came down to a low tree branch and then into the coupler. It seemed to perform really well on TX and RX. Below is a little clip recorded by Dave M0TAZ. Running 100w from the Icom IC-7200.

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I went down to the river Thames a couple of mile from home today for some portable operation and some experimenting with an end fed half wave antenna. I recently built a Parallel tuned coupler for feeding end fed half waves from 7-30MHz and this was tested on a few bands. I wanted to try 15m, but the band was full of contest stations due to the Scandinavian contest, so I cut a piece of wire for a 17m vertical. Below is some video took by Dave M0TAZ of me working Chris SM0OWX on 18MHz.

I have used the coupler on a few different bands now in various configurations with good results. I shall add a post with more results after some more tests and fine tuning soon. Here is a photo of the inside of the unit. 73 John.

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Anytone AT-588 on 70MHz

Anytone AT-588 on 70MHz

Today, I finally built a ½ λ dipole for 4m. I have previously been using a folded ½ λ dipole made out of 450Ω balanced feeder, suspended in the loft, which is not ideal. I still had the coax outside on the roof and the pole which were both used previously for my 2m/70cm co-linear, which has been relocated to the chimney, so once it was built, it was simple enough to put up.

Inside the waterproof box

Inside the waterproof box

I was thinking about building an end fed half wave dipole, having previously built a ‘prototype’ which worked well. This requires a matching section at the base, but no boom arm is needed. I also thought about a slim jim / J-pole, but the total length would be 3 metres. So, I decided to go with a trusty ½ λ centre fed dipole. I built it using two 1 metre lengths of 6mm aluminium tube, and all terminations are inside a waterproof electrical box. Inside, I also placed a coax choke balun, which is built out of a 25mm piece of pipe, with 11 turns of RG58 coax wrapped around it.

Coaxial choke balun

Coaxial choke balun.

I thought I might have to trim a bit off the 1m elements, but once I put it on the mast, the analyser showed the lowest VSWR of 1:1 at exactly 70MHz, so I left them as they are! The only thing I forgot was to put self amalgamating tape around the PL-259 plug after putting all my tools away! All watertight now though ;)

Hope to work you on 70MHz! John.

70MHz Dipole

The new 70MHz Dipole

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