Langstone build thread - join in the fun!

[radiogareth]

It's good to share, so here is my first little bit of this excellent project which I used yesterday on 4m for a two-way FM QSO across town. And my latest Pluto arrived today from Digikey (cheaper than Mouser and Farnell), already upgraded coverage and dual CPUs and tested across the shack on 5.7GHz. Better TXCO on the cards soon too.
Not wishing to damage the Pi screen or attached Rpi and not having finalised WHAT I want on the front panel yet (when I do I'll design something), some sort of stand was needed.
Print time is about 40 mins per leg, I used 20% fill, 0.2 layer height, no support and Qty 4 cheesehead 6x3mm screws.
I can't attach the .stl file but message me if you would like it.
Gareth G4XAT

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[radiogareth]

Having just had a QSO across the shack with myself on 5.7GHz (twixt Langstone and another Pluto on SDSR#) I got to wondering about improving the front end capability of the Pluto with filtering and some more gain.
Pipe cap filters seem ideal for 13cm upwards - I made one for 3.4GHz and it looks spot on in SATSAGEN. Comparing the Pluto on RX (admittedly only on 70MHz so far) with my PYE MX294 conversion and the Pye (not that great) was about 3dB better than the Pluto (and my RSP1 actually!).
50 ohm in out amps are widely available (e.g. https://www.skyworksinc.com/-/media/Sky ... 00528J.pdf is used in the Portsdown somewhere as I bought spares, there is also TQP3M9009 and SPF5189Z which are good to 4GHz [well, certainly 2.3!]).
'Ready-made' boards are all over ebay with a variety of these amp chips fitted. https://www.ebay.co.uk/itm/TQP3M9009-HI ... SwngJd9E1s
The chips are easy to replace too....
So an amp to suit the band, pipe cap filter to clean it up, into the RX port on the Pluto. Gain and filtering in one? The pipecap filters would do good service on the TX side too, although that may involve a relay. I have one SMA unit, rated to somewhere much above 5.8GHz so with careful system planning, a fairly compact filtering in/out/gain block can be realised.
Well it sounds like a plan to me......
Gareth

[G8GKQ]

Hi

I always overcomplicate things, but here is a quick and dirty block diagram of my Langstone. I must admit that a few of the blocks are not yet installed, but basically it works, and has been on the air for local QSOs.

The 6 sockets shown on the right hand side are on the box side panel and connect back into the unit to the PAs and T/R switching. This means that it can replace my FT290 (3W o/p), replace my FT790 (and provide an increased 5W output), provide 10 mW of drive at 2.4 GHz, 5 mW of drive at 3.4 GHz and has potential for other uses.

Well done Colin!

Dave, G8GKQ

[g0mjw]

Very nice. It will be interesting to compare with Lime RFE - when it arrives. For those that don't know, the LimeRFE is a filter / amplifier board with control based on an Atmega328 . It develops about 1W from HF to 13cms and a bit less on cms. It's part of LimeSDR family but not tied to it, it will work with any SDR including the Pluto. This, though not cheap, might be a good option for those not wanting to build their own front ends. It does not do 6cm, yet. It should work with the Langstone/Pluto with suitable glue software - the Atmega328 is apparently compatible with the Arduino Nano. I suppose there is no real reason Langstone can't work with the LimeSDR either as its GNURadio based.

Mike

[radiogareth]

Good to have several routes
I've been using a surplus NOS SONIC headset that i seem to have bought several of many years ago.....it works fine once re-plugged with a pair of 3.5 stereo jacks.
I've also got some old mobile phone hands-free mics units (40mm square plastic box with sun visor clip on the rear) and these need 'phantom' power up the 2-core screen+core audio lead. The one I tested has AGC action too so quite handy for using on DATV as I can walk around the shack and still be heard etc.
I tested the hands-free mic with a 'Daffodil' USB sound adaptor 7.1 Channel Sound' dongle bought a few years ago for a RPI (but on my PC) and it provided over 3 volts on the Mic jack. The small unit recommended for the Langstone only does 1.9V which isn't enough to make the mic work. Had a look at the dongle pcb and there's a 2K2 resistor that seems to feed the volts to the mic socket.
1. Trying the Daffodil dongle on the Langstone didn't work (I thought Linux was good at sorting drivers etc??)
2. Reduce the 2K2 and see if it helps
3. Add a seperate feed direct from the USB 5 V via a 1K or similar.
4. Other suggestions from more learned operators

Thanks

Gareth

[g4eml]

Hi Gareth,

Linux is not good at sorting drivers! Especially for sound. The sound system seems to be very confusing and messed up.

At the moment you need to edit the SSB_TRX.py file to work with other audio devices. I would like to find a way to make it possible to do that some other way.

For your microphone power you could add a series capacitor to the input and then feed a separate supply directly through a couple of resistors from the 5V supply. Put a large capacitor from between the resistors to ground to smooth out any noise on the supply.

The currently recommended sound dongle is just the one that I know works. Although it is cheap it has quite a high noise level. I am sure there are better ones. I will do some testing

Colin.

[radiogareth]

Had a quick browse on eBay for sloping front boxes and found this :https://www.ebay.co.uk/itm/Sloping-Box- ... 0667.m2042
Visible area of the RPI screen is an easy fit (with a 3-D printed insert) and very visible even at a shallow angle. Or, it might stand on its 'back' and then you'll have a sort of upright piano arrangement with buttons and knobs on the horizontal part.
Anyway, I've order 3 (for other projects you understand,and the 'it will come in useful one day' pile etc)

Gareth

[radiogareth]

Whilst listening to my local 4m net yesterday (70.300FM SE London Thursday eve 8pm) I tried my Langstone. Compared to my PYE MX294 it wasn't 'cutting the mustard' (bit deaf) so I wondered out loud if I could re-use front end and TX strip from some old PMR gear (which, unless you've thrown it all out, WILL come in useful one day!).
I recall that I bought a Pye M294 low band for peanuts a while back and the wonders of google threw up the full manual as a pdf (search pye m294 manual and it comes up with www.peel.dk › pdf › PYE M294 [don't click the link, use google search]). And its pretty much perfect for my application. Good filtering in and out, little bit of extra gain (not looked hard at the circuit yet but might be DC adjustable as it mentions it has AGC in that RF stage) and a 25 watt FM TX strip. All controlled by a changeover relay.....now this really WILL come in useful one day....soon....

Casting my 'untrained' eye over the PA it looks as if the TR35 predriver is biased up but not the PA, so that will need some experimenting with for SSB use. The transistor is a wierd one, ON751, listed as a VHF power device, but available on the surplus market for £3 should you kill one. Can't find any data for it but I imagine a whole lot of other devices might fit, maybe even a new MRF100......(would need guidance on matching required - see 'untrained' earlier...).
Whilst not particularly compact, for the filtering, changeover and PA strip it should make a great outboard 'box' for 4m use. This principle can be extended into my pile of 'stuff TWCIUOD' such as a old MM 70cms transverter, FM PA block from an old PMR, 23cms transverter, brick amp etc. Whilst nothing specific for 13cm I can make pipe cap filters, plenty of MOD-amps and have several PA options. For 3.4 I've a Ionica Front end mixer to cannibalize (PAs are good to go direct), leaving 5.8. Seems I picked up a 15W pa for that band a while back too, just some RX front end needed..... (just).

Going to be busy....for years.....

And now we have the Activity month to distract

Gareth

[radiogareth]

Nice sloping boxes arrived yesterday so printer busy making some 'stand up' feet as a first move.
In terms of I/O planning, I'm wondering if an adapted mouse/rotary encoder circuit can be used in parallel with a real mouse or if it needs a separate USB port. (#1)
Pluto is only USB 2 so it can stay on a USB 2. (#2)
MT should have USB 3 (#3)
Audio dongle (#4)
C920 Webcam (#5)
Lime SDR (for the Portsdown option) #6
Don't really need a Videocap dongle with so many other sources.
Network port for upgrade etc.
Band switching/external amp control/ptt etc
DC in + voltmeter DC in/DC pi
If I need more USB I'm assuming I'll need a small powered hub to do the job of sorting out whats on what so a decent 4-port USB3 would seem a wise addition....

Gareth

[radiogareth]

Progress that does at least protect the glass edges of the RPi screen from inevitable damage. Pi camera added for video of the operator. RPi Camera 'clones' now only £4.99 delivered on eBay.
DC voltmeter module to show Vin, off or V RPi.
Remote LEDs to show what the RPI is doing (on, SD activity).
RPI standoff pillars needed shortening by 3mm to get the case back on.
Now thinking about the lower panel and I/O.
DC on/off and Indicator LED.
Be nice to have a rotary encoder option but it won't support 'two' mice plugged in at the same time (not surprising....).
External RJ45 socket for upgrading.
Will probably fit a Pluto inside (out of harms way in shack, WAT on the u-USB socket etc.).
D socket for band switching DATA and external PTT etc.
At least one USB for Lime SDR usage via Portsdown as and when.
DC in and out.
Mic and headphone sockets, speaker and volume.
Onward....
Gareth

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