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RADARC on Discord

Hope you are all keeping safe and also well hydrated in this heat!

Some members may not know that RADARC is now running a Discord server. Discord is an internet-based chat tool that runs quietly in the background, and is great for those times between meetings that you just remember something you want to discuss, either to someone specific at the club, or as an open discussion. It’s much more lightweight and quick turnaround than email is.

It’s available for Windows, Macs, iPhones and Android phones, is free, and pretty easy to use once you’re up and running. There’s been lots of interesting chat already on lots of different topics, and you can mute what you’re not interested in. The only thing missing is you!

If you’re interested, ping someone on the committee directly for an invite, or email committee @ radarc.org.

Motorola MC Micro Audio Connector

I have designed a 3D printable audio adaptor for the Motorola MC Micro radio. The design cab be downloaded on Thingiverse here :-
https://www.thingiverse.com/thing:4495393

The design consists of 3 parts. The first is a grip which wedges between the internals of a 9 pin d-sub plug and the chassis of the radio. This isn’t strictly necessary but does help to avoid the plug vibrating loose. The internals of different plugs might vary so this grip might not always work but the design is made available in Tinkercad to tweak if required. I tried making a plug which would go all the way around but the minimum thickness of plastic most printers use is 0.4mm and there was insufficient space for this to work.
The second is a plate which holds the phono socket while making it easy to access the nut to do it up tight.
Finally there is a simple spacer piece to stop the end of the phono socket touching the d-sub contacts. This part is 20mm long and can simply be scaled to a different height when printing to compensate for a phono socket which has a much greater or shorter required depth.
All designs can be customised in Tinkercad :-
https://www.tinkercad.com/things/0ovB8h3qDyu
https://www.tinkercad.com/things/6fBdhwGSO4z
https://www.tinkercad.com/things/6zapnxmezA9

Parts Required :-
1* 9 pin d-sub plug
2* M3 * 30mm screws
1* phono socket

You will need to remove the metal surround from the d-sub plug. You might be able to snip it away using some cutters but I used a dremel type device with a small cutting disc to chop through it at the top and then peeled it back using a pair of pliers. If you do this please wear safety glasses as these small discs can shatter very easily if they catch and the sharp pieces can go flying off at quite a speed.

Step 1 is to push in the d-sub plug and then push in the grip behind it.

Next take the phono socket and solder wires to it and the solder ring. Make sure you do this before fitting as the heat will very easily melt the plastic.
Fit the phono socket. The plastic tends to deform a little under constant pressure so even with a spring washer it might loosen a bit after a while so I would suggest adding some silicone to fix everything in place and help stop the socket from rotating.

Feed the wires through the spacer and solder them onto the d-sub plug onto the speaker contacts.

Screw everything together and fit a phono plug onto the end of the speaker wires and it’s ready to test.

Motorola mc micro power connector

I have designed a 3D printable plug for the Motorola MC Micro radio. The design cab be downloaded on Thingiverse here :-
https://www.thingiverse.com/thing:4457417

The design has a few close tolerance parts to ensure the pins fit well in the connector. Depending on the printer the holes may need to be enlarged or made a little smaller. The plug itself is not a snug fit inside the socket and relies on the connectors to provide the friction to hold it in place so there is a little room to enlarge or shrink it before printing but I have also made the tinkercad project accessible if anyone wishes to modify the design themselves :-
https://www.tinkercad.com/things/4f8kZqtST4c

The crimps used inside the plug are Molex 5.08mm commonly used in PC power cables as in the photo below. So you can either buy a lead and remove the pins from it or purchase the crimps separately but these can be fiddly to assemble if you don’t have a crimping tool.

I bought the crimps on ebay and crimped them myself as I didn’t want to have to join the wires. I got them from https://www.ebay.co.uk/itm/Male-Female-PC-Power-Supply-Peripheral-Connector-Crimps-Molex-PSU-5-08mm/232573051969

Selecting the correct cable for the plugs is quite critical. In order to be able to have the crimps grip and hold the insulation properly you will want cable with an outside diameter of between 1.9 and 2.5mm. That is quite small considering the radio can draw in the region of 8-9A. In that size range you could get something like https://cpc.farnell.com/pro-power/14-0-2rbcopper50m/cable-figure-8-14-0-20mm-r-b-copper/dp/CB17492 which has a cross sectional area of 0.44mm. At 8A you are going to get a voltage drop in the power cable of 0.6V per meter (reference https://www.12voltplanet.co.uk/cable-sizing-selection.html) which is going to become significant at longer distances.
This is one of the reasons that you can see in the final photo that I chose to make an adaptor lead. The length of the adaptor is kept relatively short in order to minimise the voltage drop along the thinner cable.

The first step is to check that the pin crimp fits snugly. It is not quite round and in one direction it will be a loose fit and in the other it will be tighter. This orientation gives the best fit.

There could up to around 8-9A going through the contact when transmitting so it needs to be a good tight fit. It is probably a reasonable contact but of you flatten the end just a fraction it will be a lot better. Flatten in he orientation shown below so the naturally wider part becomes a little wider.

Next crimp the connectors. Start with the pin you have just squashed and crimp the ground wire to it. I had a crimping tool and found the ‘AWG 18-22’ setting worked well as you can see in the above photo. You could use a pair of pliers but it would be difficult to get the crimp as neat and small enough to fit in the back of the plug and you would probably want to add some solder.

Put the pin in first and then the socket. When pushing in the socket connector make sure it is orientated so that the pin naturally likes to twist into the correct orientation in order to make inserting the plug easier.

When the socket is inserted it will push in most of the way and them seem to stop in the position shown below. There are small barbs on the socket and you can grip the cable just behind the metal and then push it the rest of the way in and it will be a good tight fit.

That’s it pretty much assembled. When removing the plug the pin will tend to try to pull out of the socket. This isn’t a problem but you can add a bit of glue or put on some heat shrink (the stuff with adhesive if you have it)

Finally I prefer to have the plug almost a permanent fitting so I made it into a short adapter lead with a XT30 connector at the other end so if I wan’t to disconnect the radio I can just unplug the XT30 instead.

GB3BN net summary 9th April 2020

Wonderful to hear so many people on BN again. Here are a few of the salient points:

Great discussion about birds and wildlife. Some thoughts there may be changes in red kite behaviour in that they may take small prey. Robin G4IWS reports on turf wars over his nesting box; nuthatches involved. Graham G3XYX reports it’s great to hear the song thrushes in full voice.

Lots of projects on the go, too many to mention – Tom M0LTE using ammo cases as enclosures/housings; Loz G2DD looking to calibrate his power meter. Simon fixed an IC260 2m rig – dead ‘OR’ gate CD4071 IC I think it was and is now being driven mad, like me, by a microwave modules transverter.

Big shout out to Gareth M7GRB for supporting our carers by 3D printing face shields.

On that front, remember there’s the RSGB ‘Hope’ QSO party (can’t remember who mentioned that): https://www.rsgbcc.org/hf/rules/2020/rhqp.shtml

Min G0JMS has had a shack tidy, or so he claims 🙂

A possible talk we could look into is Dud Charman G6CJ’s Aerial Circus – or recreation thereof.

Dave’s WIRES-X/Yeasu fusion gateway MB6IOX is there for all to use (https://www.ukrepeater.net/my_repeater.php?id=3214). Min and Gary G4FLY also have gateways.

A source of RF noise found and summarily shot: a talk talk router and possibly a USB charger.

John bemoans the lack of the old GB3RAL beacons (28.215, 40.050, 50.050, 60.050, 70.050)MHz and GB3BAA on 50.016MHz and 70.016MHz and wonders if RADARC might be able to support at least getting something back on air in the lowband VHF region.

Here is the full cast list, with signal strength in dBm on the BN input at Bill G4WJS’s location in Stokenchurch (where recorded):

Tom M0LTE (-125)

Graham G3XYX (-109)

Chris G4CCC (-103)

Mike G4CDF (-118)

Chris M1CYE (-128, then -120)

Michael M0MPM (-122)

Bill G4WJS

Jim G0LHZ (-125)

Simon M0ZSU (-121)

Andy M7ANR (Fleet) (-124)

Loz G2DD (-128)

G4ZRZ (sorry – didn’t get a name, could have been via echolink)

Robin G4IWS (-119)

Min G0JMS (-99)

Dave G0TKV (-102)

Gareth M7GRB

Vin G4JTR (-100)

Gary G4ELD

Thanks to Bill for the signal reports on the input.

Next net: Thursday, 23rd April 2020, 8:10pm GB3BN

73

John

G4RDC

GB3BN net 8pm 26th MARCH – A Summary – thankyou!

On the evening of what should have been the spring junk sale 2020, postponed due to COVID-19, we had a net on GB3BN with 23 stations joining. Now, more than ever, communication is important . We did that in spades.

I thoroughly enjoyed running the net. It was fantastic to combine getting on the radio and having a club meeting. Looking back, we really did that using the technology we love. At 8pm, I didn’t know that would happen. All I had was a beer and the radio by my side. By 10:30pm I had a list of 22 callsigns (with ticks against them, finally, to indicate signout) and it really felt like the end of a normal club meeting, or even better because everyone took part and contributed. This virus will not stop us.

Operating procedures were first class. Everyone. No exception. New M7 operators/callsigns? Flawless.

Because it was so productive, I thought I’d try and capture a few points.

Firstly, it was wonderful to be able to collectively say THANKYOU to our magnificent NHS together, on air, using BN’s huge coverage area.

Other:

  • In these uncertain times, this net is a place where we can all gather on 2nd and 4th Thursdays where we would have had a face to face club meeting. To ‘check in’ if you like.
  • Following on from the BATC’s support for online meetings and their offer of support for clubs, it is clear they are something RADARC needs to pursue. In particular, a number of members enjoyed Noel G8GTZ’s QO100 talk.
  • Lots of practical tips for surviving the ‘lockdown’.
  • Finding out about other nets (eg. G1RAF has a net on GB3TU 433.225MHz: 12:00 and 19:00 daily).
  • Discussion about new conferencing technologies: eg. zoom, discord.
  • Propagation news: HF, VHF. There are some signs Sporadic E is starting on the high HF bands and 50Mhz. The Poldhu net on 80m was in fine fettle.
  • Virtual sharing of beer and biscuits (Jammie Dodgers no less) in the finest Reading tradition. (There should be bulbs in there also – gardening did feature).
  • Updates on construction projects – reports of exploding tantalum capacitors.
  • The trials of home working.
  • Clarification on how the local repeaters work with CTCSS. You get a ‘T’ in morse if you’re running CTCSS, ‘K’ otherwise. Soon, I think, you’ll need to run CTCSS. see http://www.tvrg.org.uk/ for details.
  • Our ‘YouTube’ channel with videos of previous talks (thanks to James 2E0JPM) is https://www.youtube.com/channel/UChamISEy8HRvKmWN0-GTWpA
  • Loads more. If I’ve missed anything you would like included here then please let me know.

Thankyou for a special evening.

73

John

G4RDC

The net:

Bill G4WJS

Dave G0TKV

Graham G3XYX

Michael M0MPM

Jim G0LHZ

Tom M0LTE

Mike G4CDF

Simon M0ZSU

Nick G0LGG

Sergei M0TLN

Gareth M7GRB

Vin G4JTR

Denis G4KWT

Tom 2E0YGW

Robin G4IWS

James 2E0JPM

Chris G4CCC

Guy 2E0GDC

John M5ET (echolink)

Sean 2E0ZIP

John M7IJV

Loz G2DD

John G4RDC

Apologies for getting any callsigns wrong. Now you can see why. The raw material for this post.

Junk Sale (26th March) postponed

Dear Members,

For reasons I am sure you can guess, we have decided to postpone the junk sale scheduled for the 26th March. As you know the room is always packed, and with various things changing hands it would prevent a high risk of spreading the virus. We are sorry about this and I myself am disappointed, but, we are hoping to be able to reschedule it later in the early summer.
Unfortunately the lectures planned for April will also be postponed for similar reasons, but again we hope to run the same lectures later in the year or early next year.
As we are radio amateurs, we hope to make use of this to stay in contact and socialise over the air waves, so we will be announcing at net to take place at the time when we would usually have a  ‘pass out’ so at least we can still chew rag!

We will send out regular emails with any further news.

Take care, and good health to all of you, do keep in touch.
73 Simon M0ZSU

Solar orbiter talk postponed

Chris Brockley-Blatt is unwell so the Solar Orbiter talk planned for this evening is postponed.

We will still meet at Woodford park for a natter night and chance for anyone to do a short talk if they wish.

We will also have a go at the 50MHz UK Activity Contest