Another toy

A new dual band DMR handheld was being advertised at $86.99 from Radioddity.  I was a bit sceptical at first and thought it might have turned out like the Baofeng DMR HT in not being Tier II compatible.  But initial reports were ok so I took the small plunge (as it cost less than €75 delivered).  It works pretty well although the CPS software is in need of a bit of work.  RF performance is fine although it really does need adjustable squelch levels on analog and picks up too much intermod.  The small screen and inability to load the dmr database are also negative points.  But for the money it is a capable dual band set.

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Another shack addition

One of the niggles I had with my new IC-7300 was that it could not drive the dynamic mic that I had been using with the IC-746.  I suppose I could have got a pre-amp but that would have meant another box on the shelf and more wires (and the 7300 was doing a good job of keeping that clutter reduced).  So I decided to go for a headset.  The Koss SB-45 comes highly recommended by a lot of people and has an electret element so it would work nicely with the 7300.  The only problem was getting one this side of the Atlantic at a reasonable price.  Luckily Tony EI7BMB was going back stateside and kindly offered to bring one back for me.  So the new headset cost me less than 30 euros to my door.  Anyway its a great headset and comfortable to wear for long periods and the mic works well too.  I am adding myself to that long list of people recommending the SB-45! BTW Tony got himself the SB-40 with a dynamic element as is equally pleased with it.

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ILLW Weekend

I will be QRV at Ballinacourty Point Lighthouse with the members of Tipperary Amateur Radio Group for the weekend of the 19th/20th August for the 20th International Lighthouse Lightship Weekend.  The reference number is IE0018 and we will be using the callsign EI7T.  This lighthouse has not been activated for a number is years so I expect demand to be high.  But we still hope to have a few beers as well!

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A new rig…

Finally I took the plunge and splashed out on a new Icom IC-7300.  I didn’t really need it as my IC-746 was still doing its job admirably.  The first hiccup was that I couldn’t use the dynamic vocal mic that I was using with the 746 – the preamp in the 7300 is just not good enough.  I do like hands-free operation using a foot switch so this was a disappointment.  So I made an adapter to use a headset that I had in the shack and that is working well although it is a bit heavy.  I have a Koss SB-45 coming from the States shortly.  Side-by-side tests with the 746 on the same antenna (I split the feed) showed no improvement in signal reception (although NR was better on the new rig) despite the specifications.  Also the noise blanker on the 746 deals much better with the electric fences in my area.  But other than that everything else is positive.  The touchscreen is easy to use and the menus are well thought out.  I didn’t need to look at the manual too many times.  Frequency stability is very good on the higher frequencies such as 6m which is very important for the digi modes – the 746 does suffer from drift.  A big plus is that no rigblaster or similar interface is needed – the radio and pc connect with a single usb cable – no audio cables are needed either.  And of course the band scope is very useful even though it is a bit on the small size – a much larger screen will be on the 7610 but I wont risk getting one – the station manager hasn’t noticed this purchase yet so I wont push my luck.

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New antennas

While my end-fed wire antenna covers most of my needs I have had no proper antenna for either 6m or top band and have been relying on a tuner to get on these bands which has proven not very efficient.  So I went off to Limerick and purchased a 6m length of 12mm aluminium tubing and for the boom I used a piece of 25mm plastic conduit from the electrical wholesalers.  I assembled a 2 element beam for 6m quite easily – there are lots of designs already on the web so no need to reinvent the wheel.  Even though it is only at about 18 ft high it seems to be working well.  I’ve worked eastwards as far as Russia and also a few contacts across the Atlantic.  Also while I was feeling creative I put up a 1/4 wave inverted-L for top band.  The vertical sectional is only 20ft and the remainder slopes downward a bit.  I have only buried 1 radial so far so there is still a bit of work to be done.  But the SWR is 1.5 or less across the whole band and it does radiate a little – I have worked into Russia on JT65.  The total cost of the 2 antennas came to around 25 euros excluding travelling expenses.  Rotation of the 6m is by the armstrong method of course!

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Retevis RT3 Charger modification

I recently bought a Retevis RT3 radio and assembled a DVMega hotspot to dabble in DMR radio.  While the RT3 seems to be a decent handset for the money the charger leaves a lot to be desired.  Unmodified the charger will not cut out until the battery reaches 8.6 volts which is well above the 8.4 volts of a full battery.  This must be a hazard or at best will ruin the battery quickly.  However it is easily rectified as described here RT3 Charger Mod.  I didn’t have suitable smd resistors but I still used regular wire resistors to make up 390 ohms.  However even after the mod another shortcoming was evident – the charge rate is around 150ma so takes overnight to charge.  I purchased an 8.4v charger from the orient for less than 5 euros including delivery: 8.4v Intelligent Charger

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The “intelligent” 8.4v charger.

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Before modification (the 2 wires on the left were the result of the previous modification to reduce the charger voltage).

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After modification

The modification is very simple – the charging circuit in the dock needs to be bypassed by cutting the positive track near the dc jack.  Then connect the dc directly to the charging terminals.  The red wire on the right of the picture (negative –  just needs to be relocated to the dc jack (note the track cut just to the right of this).  The yellow wire is the positive.  The positive terminal was hard wired to the underside of the circuit board – this needs to be cut.  Now reassemble.  Note that the charging led no longer functions but the new charger has a status led on it so that’s not a problem.  A full charge (to 8.4v) now takes just 2 hours and 40 mins – respectable.  That’s two birds with one stone hi.

My first contest win!

On Easter Monday I took part in the 70 cms Counties Contest.  I entered the low power (10w) SSB/FM section and set up on the top of Tountinna (about 450m ASL).  It is a great location with the added bonus of being able to drive to the top.  I used a Yaesu FT-897 for SSB and an Icom IC-207h for FM.  The FM antenna was a Diamond X300 and I just used the mobile antenna on the car for SSB – yes it seems everyone uses vertical polarization on SSB during contests!  I did bring a 7 element beam but didn’t use it.  I managed 29 contacts in 14 counties and received the top score overall.

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