Monday, 11 April 2016

Baofeng BF-888S On Test - You must be joking!

The programming lead for the Baofeng BF-888S radios arrived today, so I was able finally to ditch the factory fill (full of un-usable frequencies) and put the radios on some channels I could test them on. For a cable that cost under a quid and a half, it works very well. Even the Baofeng software is relatively easy to use if youve experience of programming software for commercial radios. Its certainly no more awkward than anything Kenwood, Yaesu or Motorola provide!

I set a few 'clear' channels, a few with CTCSS, some with DCS, some high some low power, and a couble with 'scrambler', and then headed out to give them the once over on the Marconi 2955B.

First test up, receive. I expected these to fall a bit flat, and just hoped that they would at least approach -118dBm for 12dB SINAD...

..what the? Fully quieting at -122? still going down? You MUST be joking!

According to the venerable old 2955, the radio I was testing, with its squelch set to level 3, broke the squelch at -127dBm, with little noise!

After realising that the audio output (speaker) connection was 2.5mm, and finding an adapter, I measured the SINAD. I then measured it again and again! -126dBm for 12dB SINAD!!! Ive never even got a Kenwood TK-359 to do that!

Transmit next. Modulation in Narrow mode is for my liking a bit low, but the CTCSS and DCS worked fine. Power output seems to be 1.8W in High, and in Low, er, 1.8W! I'll look into that, not sure why that wouldnt change as programmed, or with the side button set to select power level. Frequency accuracy, well on the test frequency it was 20Hz out! That will vary with temperature im sure, but thats pretty good!

As a final check, I moved one 12.5kHz channel away, and started to crank up the signal level, to see how it handles adjacent channel interference. I fully expected the radio to respond once I got to -75dBm or better. I kept going - and hit the limit of the 75W port on the test set! It hadnt even noticed a -15dBm signal 12.5kHz away! I went to the 1W port and cranked it right up to +5dBm - nothing! Not a peep!

Of course, I cant vouch for the level of desense this may have caused to the working channel, but it certainly didnt disturb monitoring.

Finally, me and Sam tested them on air out in the garden. Testing a clear channel, a CTCSS, a DCS, a High, a Low, and a 'scrambled' channel. All were good and clear over our 100ft path. The audio is a little tinny, and the mic could do with some foam sound baffle around it. But not too bad.

As for the 'scrambler' what tosh! What these radios have, and what it plainly says in the documentation, is Beat Shift. This is used to move the VCO a fraction if birdies from the CPU clock cause interference. It is NOT a scrambler, but when used with a radio that doesnt have the feature enabled could put the signal off frequency enough to make the audio unintelligible. I checked on the 2955's 'scope, and there was most definately NO speech inversion going on!

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