Back from 'Nam

We are back from our Vietnam vacay and I hesitate to write this since no ham radio was involved...so I'll keep it short.

Despite my efforts on parallel avenues long before the trip started, I was unable to get permission to operate from Vietnam - couldn't even get permission to bring a transceiver into the country. I have thanked the two Vietnamese hams who tried on my behalf. It seems impossible - I don't know how some DXpeditions have managed.

Our trip had no shortage of bad things happening: Typhoon Halong (while we were at sea) and Typhoon Fengshen hitting us just north of Danang. Also, my smartphone stopped working as did my debit card. Minor inconveniences compared to the storms, but still...

On the good side:

Hermes Lite 2, 10-160m harmonic output

I went through the rest of the bands today and the HL2 looks good on all of them. My HL2 includes, of course, the N2ADR Low Pass Filter board, as they all should (and probably do).

 

10m

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12m

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Hermes Lite 2 - Compliant on 10 meters?

While waiting on an "Your Anan-10E is ready" email I thought I'd test a claim on Apache Lab's website regarding SDR radios that use the AD9866 processor - ie, the Hermes Lite 2.

Apache Lab's comparative chart claims that the HL2 is not compliant on 10 meters. News to me...let's have a look.

[UPDATE: Harmonic content is within spec on all bands. I'll check IMD later in the year.] 

I also wanted to test receiver sensitivity. I was asked about it in several emails after posting a video comparing receiver sensitivity of the QMX+, KX2 and FT-891.

 

I'll be the first to admit that receiver sensitivity is down the totem pole when it comes to receiver specs, topped by selectivity and dynamic range. Still, it's a useful test if only to verify the lack of a problem where one might be suspected.

Undocumented feature of 60dBm's Neptune 100-watt HF amplifier

I was rearranging the rat's nest of cabling that constitutes the best-unseen space between my operating desk and the wall yesterday when it happened...

Once everything was satisfactorily cleaned and ship-shape, I fired up the Hermes Lite 2 and the Neptune amp that I've had for about a year now...and something wasn't quite right.

For starters, the green "ON" LED was blinking slowly rather than remaining steadily on.

More significantly, automatic band changes weren't occurring.

I could switch bands manually by short-pressing the "ON" button and I had full output on every band - just no auto bandswitching.

A look around 60dBm's website revealed that there is no online manual for the amplifier. Great. So I fired off an email and received the following reply from Paul UU0JR in Ukraine less than an hour later.

Building and testing an eBay diplexer kit for 2m/70cm

The recent purchase of a UV-Pro has me in need of a satellite antenna for the "Easy-Sats" and International Space Station.

Arrow makes the perfect antenna but I thought I could homebrew one at a much lower price.

The main component that differentiates the Arrow from other dual-band Yagis is the diplexer, not duplexer, as it is incorrectly called by Arrow (and others).

A search online located several suitable but expensive diplexers for the necessary bands - and one inexpensive kit ($13) from a US seller on eBay - Steven AI4NV.

The kit arrived today and took all of 10 minutes to assemble.

There are three SMD capacitors and three coils to wind; two on torroidal cores and one air-core. An aluminum tube is included to assist in winding the air-core inductor.

After winding the coils and soldering all 9 parts to the board, it was time to tune the diplexer.

The instructions that come with the kit mention that a dummy load should be placed on the port not being tested, implying that the port being tested is left open. In reality, a dummy load should be placed on both ports.

The idea is to tune each output for minimum SWR with that output's frequency being injected. This will result in minimal insertion loss and maximum rejection of each band from the opposite port.

It is important to make sure that the dummy loads used are adequate up to 450 MHz.