Saturday, 29 December 2018

DATA Socket

I'd been using an FT-847 with a data modes interface to my PC, completely isolated with transformers in both transmit and receive paths and a mechanical relay to switch the PTT. It used the 3.5mm jack on the rear of the FT-847, which is what you must use for transmitting on SSB (the usual 6-pin mini DIN is for FM transmit only).
Everything worked OK on data modes like FT-8 and WSPR, but I noticed that when making a recording of voice, there was something wrong with the frequency response. At first, I thought that this output might be bypassing the de-empasis circuit on FM, but when looking at the frequency response, even on SSB it rolled off below 1KHz.
The transformers I used in the interface were from a 'ground loop isolator' designed for car audio systems, and when tested between the output and input of the PC, showed a response within 2dB down to below 100Hz.
Eventually I thought about the transformers and their impedance. 600 ohms is a common value for them, maybe there was a mismatch between that and the output impedance of the radio.
Checking the schematic for the FT-847, the final op-amp in the 'RX1200' circuit goes to a 100nF capacitor, then this goes through separate 4K7 resistors to both the 3.5mm and DIN sockets.This would explain why there was such a big cut in low frequencies.
At the worst case, driving a short circuit, the 4K7 and 100nF would make a high pass filter with a frequency of about 340Hz. The specification of the data output says a 10K impedance, and with a 10K impedance (which would be in series with the 4K7), the frequency would be around 100Hz. That's fine for any voice or data modes, even 340Hz would be usable.
But the transformer will also create a R-L high pass filter, with its impedance increasing with frequency (DC resistance is about 100 ohms so increasing from that), against the 4K7 resistor. This output is not really suitable for driving an isolating transformer if you want anything like a flat frequency response.
The resistor and capacitor could be replaced with different values (higher capacitance, lower resistance).
I had a look a schematics for other radios made by Yaesu, that had a 6-pin data socket. Although they all used similar op-amps to drive the RX1200 output (NJM2902), 3 radios had 3 different combinations of resistor and capacitor in series.
FT-847 - 4K7 / 100nF
FT-817 - 1K / 1uF
FT-8900 - 220R / 1uF
That's a 20:1 range of output impedances, although every time this is specified as for use with 10K input impedance on whatever equipment is connected. If you're making a direct connection from the radio to the Line In of a PC or amplifier, it probably won't matter as the input impedance will be quite high. But the circuits for most home built and commercial data mode interfaces have isolating transformers, and will affect the frequency response.

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Thursday, 25 October 2018

September

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August

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Tuesday, 23 October 2018

Payphones

Long ago, before everyone had a mobile phone, I started making a directory of payphone numbers in my local area and places I'd visited. A lot of these will have been removed now, but just in case anyone fancies dialling a random payphone, here is the list (last updated January 1999).


The photos are of the payphone listed above it, taken in early 2003


Bowland Bridge, Crosthwaite 01539 568451

by 124 Highgate, Kendal 01539 720441

Car Park, Peppercorn Lane, Kendal 01539 728053
01539 722471

by Working Mens Institute, Market Place, Kendal 01539 729993
01539 728286

Level 3, Westmorland Shopping Centre, Kendal 01539 721644
01539 721638

by Iceland, Highgate, Kendal 01539 732950

by 181 Highgate, Kendal 01539 726562

outside Royal Bank of Scotland, Market Place, Kendal 01539 724291
01539 724226

Bus station, Kendal 01539 720831
01539 720887

South Road/Milnthorpe Road, Kendal 01539 724227
01539 728230

Market Square, Masham 01765 689287

Parliament Street/Piccadilly, York 01904 621101
01904 644534

Outside Marks and Spencer, Picadilly, York 01904 654186

Taxi Rank, York Railway Station 01904 670244
01904 623041
01904 623499

Castle Museum car park, York 01904 640283
01904 640285

River Bridge, Gargrave 01756 749430

Co Op, Market Street, Dalton 01229 466534

Barrow indoor market 01229 825299
01229 825247 these don't receive incoming calls

Platform 4, Lancaster railway station 01524 841301
01524 841302

Beaufort Grove, Morecambe 01524 418354

Broadway/Stuart Avenue, Morecambe 01524 417800

Platform 3, Lancaster railway station 01524 841303
01524 841304

Opposite Main post office, Lancaster 01524 63411
01524 63603

Market Street/King Street, Lancaster 01524 65951
01524 846136

by Woolworths, Lancaster 01524 33930

by HMV, Lancaster 01524 33976

outside 28-30 Cheapside, Lancaster 01524 846135
01524 846131
01524 847970
01524 847863

by Marks and Spencer, Lancaster 01524 846140
01524 32314

by 51 Penny Street, Lancaster 01524 846304
01524 846375

New Market St/ King Street, Lancaster 01524 847388
01524 64917

station approach, Meeting House Lane, Lancaster 01524 841300

Langdale Road, Grasmere 01539 435608

by Red Lion, Grasmere 01539 435285
01539 435637

Broadgate, Grasmere 01539 435864

Moot Hall, Keswick 01768 772114

Dale View, Lake Road, Keswick 01768 774935

Bell Close, Keswick 01768 774938
01768 774939

Derwent Close, Keswick 01768 774796

Outside Keswick Post Office 01768 772359
01768 774932
01768 774933

by Spa, North Terrace, Whitby 01947 602787

Royal Crescent, North Terrace, Whitby 01947 605362

New Quay Road, Whitby 01947 606053
01947 606054

Khyber Pass, Whitby 01947 603327
01947 606055 card phone

by Masonic Hall, Redcar 01642 487242
01642 483224

Cleveland Street, Redcar 01642 482789

by Leos Club, Redcar Front 01642 482011

by Woolworths on Redcar front 01642 494250

Aske Road, Redcar 01642 482415

King Street, Redcar 01642 490998

by Station, Hartlepool 01429 269103

square by end of Tower Street, Hartlepool 01429 266114

in Middlesbrough railway station waiting room 01642 244380

Broadfield Road, Hartlepool Headland 01429 268100

outside First Freeze, Main Street, Redcar 01642 486328

North side of Redcar clock tower 01642 482833

by Winning Post, Redcar 01642 482306

outside Kwik Save, Main Street, Recar 01642 494152

High Street, Stockton 01642 676362

by BT shop, Middlesbrough 01642 244107

opposite Bankrupt Warehouse, Middlesbrough 01642 242841

Grange Road, Middlesbrough 01642 250804

Gilk Street, Middlesbrough 01642 250905

by Binns Store, Middlesbrough 01642 243737

Thornaby railway station 01642 603861

on Redcar central Station 01642 494792

by Burger King, Middlesbrough 01642 242544

near BHS store, Middlesbrough 01642 250816

by Coatham School, Redcar 01642 482198

new Colliery Road, Skinningrove 01287 640321

Newcomen Terrace, Redcar 01642 482279

Main Street, Hawes 01969 667221
01969 667684
01969 667227

by Doctors Surgery, Hawes 01969 667309
01969 667242
01969 667683

inside Forum 28, Duke Street, Barrow 01229 838030 no incoming calls

Kirkby Crossroads 01229 889219

Thwaites 01229 772634

Whicham, Silecroft 01229 772535

Devonshire Road / Furness Street, Millom 01229 772616

Mainsgate Road / Devonshire Road, Millom 01229 772139

Market Square, Millom 01229 774167
01229 772242
01229 770376

by Millom police station 01229 772255
Huddleston Road / Salthouse Road, Millom 01229 772130

Main Street / Sandham Lane, Haverigg 01229 772240

Silecroft Village 01229 772144

Poolside, Haverigg 01229 772674

Kirksanton 01229 772376

The Hill, Millom 01229 772689

The Green, Millom 01229 772311

Ladyhall, Millom 01229 716200

Victoria Road, Broughton 01229 716311

Foxfield 01229 716211

by Greyhound Inn, Grizebeck 01229 889201

Kirkby Hall Corner, Marsh Side, Kirkby 01229 889254

Soutergate, Kirkby 01229 889211

Furness House, The Mall, Barrow 01229 811324
01229 824982

Roose, Barrow 01229 825285

Oxford Street / Victoria Road, Barrow 01229 820086
01229 811422

Tesco Store, Hindpool Road, Barrow 01229 813161 no incoming calls

Barrow Railway Station 01229 824955
01229 811321

Asda Store, Walney Road, Barrow 01229 870021
01229 870023

Black Bull Pub, Tudor Square, Dalton 01229 462823

Dundas Street / Holker Street, Barrow 01229 824999

Ainslie Street / Romney Road, Barrow 01229 825440

Alder Road / Schneider Road, Barrow 01229 825385

Middlefield, Ormsgill 01229 811318
01229 824908

Anson Street / Hartington Street, Barrow 01229 811216

821161

Car Park, Cornwallis Street, Barrow 01229 824934

01229 811319

01229 821205

Barclays Bank, Dalton Road, Barrow 01229 813492

01229 813478

McDonalds, Dalton Road, Barrow 01229 839726

01229 839619

RAFA club, Dalton Road, Barrow 01229 813453

01229 813457

Ocean Road / Westminster Avenue, Walney 01229 471185

Central Drive / Promenade, Walney 01229 471184

West Shore Road / Irwell Road, Walney 01229 471701

Albert Street North / Douglas Street, Walney 01229 471380

Ocean Road / Ampithrite Street, Walney 01229 473844

01229 471183

Crows Nest, Ferry Road, Barrow 01229 824965

Abbey Road / Hindpool Road, Barrow 01229 828647

Ramsden Dock Road / Ship Street, Barrow 01229 822721 no incoming calls!

01229 811316

Michaelson Road, Barrow 01229 825343

North Scale, Walney 01229 471134

Schooner Street / Island Road, Barrow 01229 811317

01229 821269

Ramsden Dock Road / Anchor Road, Barrow 01229 811315

01229 822782

28-29 Ferry Road, Barrow 01229 829189

Central Drive / Black Butts Lane, Walney 01229 471181

Mill Lane, Walney 01229 471186

01229 473843

Ulverston Road, Swarthmoor 01229 582894

Urswick Road / Meeting House Lane, Ulverston 01229 582883

Mountbarrow Road, Ulverston 01229 582301

Oakwood Drive /Bay Tree Road, Ulverston 01229 582334

Park Road / Victoria Road, Ulverston 01229 582309

Ulverston Railway Station 01229 582048

Devonshire Road / Quebec Street, Ulverston 01229 582228

Hart Street / Ainslie Street, Ulverston 01229 582275

Garden Terrace / Town Bank, Ulverston 01229 582132

Oakwood Drive / Maple Avenue, Ulverston 01229 582398

Lightburn Road / Princes Street, Ulverston 01229 583947

Post Office, Cross Street, Ulverston 01229 582266

01229 587858

01229 582216

Nat West Bank, Queen Street, Ulverston 01229 582131

01229 587688

Rosside, Ulverston 01229 582849

Loppergarth, Ulverston 01229 583985

by Majestic Hotel, Michaelson Road, Barrow 01229 825465

01229 821291

Dalton Road / Paxton Street, Barrow 01229 430014

01229 430811

Albion Hotel, Barrow 01229 820057

Crellin Street Car Park, Barrow 01229 811116

01229 822770

01229 822793

01229 811041

Cavendish Street / Dalton Road, Barrow 01229 839790

01229 839788

Ramsden Square, Barrow 01229 825418

01229 820030

01229 811117

01229 811119

St Marks Church, Rawlinson Street, Barrow 01229 824928

01229 811217

Abbey Road / Holker Street, Barrow 01229 825340

01229 825243

Lakeland Service Station, Abbey Road, Barrow 01229 837850

Abbey Terminus, Abbey Road, Barrow 01229 821175

by head Post Office, Barrow 01229 811114

01229 811115

Park Drive / Abbey Road, Barrow 01229 821105

01229 811420

71 Risedale Road, Barrow 01229 811221

01229 821215

Greengate Street / Jarrow Street, Barrow 01229 811220

01229 820022

Greengate County Junior School, Barrow 01229 811483

Salthouse Road, Barrow 01229 822732

01229 811320

St Lukes Avenue / Roose Road, Barrow 01229 811323

01229 825219

Friars Lane / Roose Road, Barrow 01229 824951

01229 811322

Holyoake Avenue / Harrel Lane, Barrow 01229 821132

Great Urswick 01229 582239

Little Urswick 01229 869561


Yarlside Road Shops, Barrow 01229 825315

Stainton 01229 462119


Lesh Lane, Barrow 01229 824910

Lakes Parade, Hawcoat 01229 821155

main entrance Furness General Hospital, Barrow 01229 870387 (no incoming)

Hawcoat Lane / Oxford Street, Barrow 01229 824921

Hawcoat Lane / Undergreens Road, Barrow 01229 825368

Gleaston 01229 869571

Fairfield Lane / Hollow Lane, Barrow 01229 822703

Double D, Friars Lane, Barrow 01229 824907

Dalton Lane / Rakesmoor Lane, Barrow 01229 824974

Oxen Park 01229 861415

Duke Street, Askam 01229 462120

Marton 01229 462011

by Garage, Ings 01539 821772

by Church, Ings 01539 821211

Rectory car park, Bowness 01539 442819

by Information Centre, Bowness 01539 446065

01539 488156

01539 488152

01539 488155

Market Square, Hawkshead 01539 436357

Hawkshead car park 01539 436436

Market Street, Dalton 01229 465752

01229 462112

Tudor Square, Dalton 01229 465671

01229 462115

Dalton Railway Station 01229 467569

Newton 01229 462041


Ruskin Avenue, Dalton 01229 462110

Lindal green 01229 462266

Ireleth Hill, Askam 01229 462051

Bouth 01229 861211

Baycliff 01229 869581

Arrad Foot 01229 861319

Cavendish Street, Dalton 01229 462772


Market Place, Dalton 01229 462193


Elterwater 01539 437665

Kipford 01556 620234

Rockcliffe 01556 630367

Greystone Lane, Dalton 01229 462174


Macyllenth town centre 01654 702817

Glan Fechan 01654 702391

Doll Street, Macyllenth 01654 702286

Centre For Alternative Technology 01654 703577 (solar power)

Platform 4, Preston Railway Station 01772 253544

01772 253373

Main waiting area, Preston Railway Station 01772 251377

Platform 3, Preston Railway Station 01772 252332

01772 251213

Westfield Street/ Water Street, St. Helens 01744 21255

Westfield Street/Ormskirk Street, St. Helens 01744 734723

Ormskirk Street/Brook Street, St. Helens 01744 22968

01744 22928

Church Street/Bridge Street, St. Helens 01744 27989

Church Street/Hardshaw Street, St. Helens 01744 454337

Outside Railway Station, Fishergate, Preston 01772 251293

01772 251223

Taxi rank, Preston Station 01772 251389

01772 251395

Car Park Entrance, Fishergate Centre, Preston 01772 561175

Ground Floor, Fishergate Centre, Preston 01772 251809

01772 254783

Bridge Street, St. Helens 01744 454243

Platform 2, Preston Railway Station 01772 555708

01772 562182

01772 555067

01772 555072

Inside La Grange Centre, St. Helens 01744 451136

Market St./Chalon Way, St. Helens 01744 453324

by St. Mary's Church, St. Helens 01744 454316

Shaw Street, St. Helens 01744 24776

by 32 Wallgate, Wigan 01942 241704

by 28 Wallgate, Wigan 01942 241768

by 7 Wallgate, Wigan 01942 825738

by 30 Market Place, Wigan 01942 242433

by Burtons, Standishgate, Wigan 01942 829994

outside Debenhams, Wigan 01942 825814

by 60 Standishgate, Wigan 01942 825982

Thwaite Flat 01229 462096

Woodland 01229 716595

Sandbach Services M6 Southbound 01270 759047
01270 764817

Chapel Stile 01539 437211

By Black Bull, Yewdale Road, Coniston 01539 441332

White Scar Caves, Ingleton 01524 242342

By Fire Station, Yewdale Road, Coniston 01539 441465
01539 441312

Wyndham School, Egremont 01946 820466

Greenhowe Caravan Park, Great Langdale 01539 437293

Hampson House Hotel, Galgate 01524 751189

Old Park Wood Caravan Site, Flookburgh 01539 558362

Longlands Caravan Site, Kirkby 01229 889520

Sheltered Housing, Manor Court, Cockermouth 01900 822785

Howtown Hotel near Penrith 01768 486497

Inglewood Residential Home, Carlisle 01228 818587

Lancaster Golf and Country Club, Galgate 01524 751353

Beck View sheltered housing, Lancaster 01524 66258

Glebe Court sheltered housing, Lancaster 01524 62468

Gummers Howe Walk sheltered housing, Carnforth 01524 733224

Kingsway Court sheltered housing, Heysham 01524 855940

Melling House sheltered housing, Lancaster 01524 32282

Parkside Court sheltered housing, Morecambe 01524 426060

Ripley Court sheltered housing, Lancaster 01524 39947

Langton Adventure Centre near Penrith 01768 482470

Lowbyer Manor Hotel, Alston 01434 381425

Quernmore Road/ Wyresdale Road, Lancaster 01524 63532
01524 841309

Bus station, Damside Street, Lancaster 01524 32578

Park Square, Lancaster 01524 841315

Scale Hall Road/ Morecambe Road, Lancaster 01524 32954

Diamond Restaurant, Dalton Road, Barrow 01229 821126

Morecambe High School 01524 417830

Penrith Auction Mart 01768 864238
01768 864490

MacDonalds Drive Thru, Barrow 01229 825759

New Road, Viaduct Estate, Carlisle 01228 591714

outside Crown and Mitre hotel, English Street, Carlisle 01228 590949

outside Binns, English Street, Carlisle 01228 590936

by Nat West Bank, English Street, Carlisle 01228 590928

by Courts, English Street, Carlisle 01228 541261

Court Square, Carlisle 01228 522261

Platform 4, Carlisle railway station 01228 526169

Platform 3, Carlisle railway station 01228 521267

Victoria Viaduct Roundabout, Carlisle 01228 596846

outside Kendal Library 01539 729917

outside MacDonalds, Kendal 01539 724127

Windermere Road/ Green Road, Kendal 01539 724247

Grapes Lane, Carlisle 01228 536562

Fisher Street, Carlisle 01228 590916

Cartmel square 01539 536431

Police Yard, Kendal 01539 723036

Burton Services M6 Northbound 01524 782095
01524 782675
01524 782674
01524 782672

Main Street, by Library, High Bentham 01524 261263

Cheapside, Settle 01729 822265

Greenfoot Car Park, Settle 01729 825280

Whitefriars Car Park, Settle 01729 825281

A65 / Leyfield Raod, Kirkby Lonsdale 01524 271523

Car Park, New Road, Kirkby Lonsdale 01524 272750

Cockley Beck, Duddon Valley 01229 716231

Hall Bridge, Seathwaite 01229 716207

outside Newfield Inn, Seathwaite 01229 716446

outside Ulpha Post Office 01229 716447

Kents Bank Road, Grange 01539 535611

Grange Fell Road, Grange 01539 533313

by Railway Station, Grange 01539 532206

Mayfield Terrace, Grange 01539 533312

Grange Fell Road / Fell Drive, Grange 01539 533311

Crag Brow, Bowness 01539 446040

Car Park, Lake Road, Bowness 01539 488162

Rayrigg Road, Bowness 01539 488143

Promenade, Arnside 01524 761296

Silverdale Road, Arnside 01524 761378

Station Road, Arnside 01524 762214

Scotch Corner service area A1 01325 377697

Killington Lake service area M6 01539 621429

Cark Railway Station 01539 558720
01539 558311

opposite Cartmel Priory School, Cartmel 01539 536311

inside Hare and Hounds Inn, Bowland Bridge 01539 568525


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Friday, 10 August 2018

Vintage Vodafone Mast

On the way back from Airdrie today, I stopped at Happendon Services by the M74 (grid reference NS850338).
In the car park is a Vodafone mast which has been there from the early 90s or earlier. There aren't many of these left, with two omnidirectional antennas for the 900MHz band. I know this one was active in 1995 with their analogue phone service (control channel 935.7625 MHz), probably GSM too by then. 
Since then, other masts have appeared, the one in front of the Airwave mast looks like newer Vodafone 900 and 2100MHz panels.
And at the far end of the car park, the antennas on that mast may be the ones which are actually in use now, as most sites now only use two sets of panels, one for Vodafone/O2 and the other for EE/Three.

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Monday, 30 July 2018

Network Radio

One of the latest things to hit amateur radio is Network Radio. What is it? Devices based on Android mobile phones which are designed to look and act like a traditional mobile or handheld radio transceiver. They give a proper Push To Talk interface to voice chat apps such as Zello (any app which can recognise a hardware button as PTT), while also being usable as an Android mobile device.
It's not really a new idea though, Voice Over IP has been around for years in various forms, and radio amateurs have used it for both internet linked repeaters and privately without connection to any transmitters. It's just the range of PTT enabled gear has recently expanded and been marketed to radio amateurs.

Inrico
Radio-Tone
SenHaiX 

Review of a SenHaiX mobile network radio by Ringway Manchester

One brand of network radios from one amateur radio dealer: 
 You can see they look almost exactly like proper VHF/UHF handheld and mobile radios, except they have no transmitter and receiver except the standard cellular/Wi-Fi radios you would find in a mobile phone. The intended market for these is the business radio user who needs to cover a wide area without setting up or renting a business radio system. E.g. a travel or haulage company. Even though mobile phone coverage now means that private business radio systems aren't essential, there will still be users who need PTT type communications (group calls, instant transmission for urgent calls).

So why does this affect amateur radio, these don't even transmit on any amateur bands (unless you count 2.4 and 5GHz Wi-Fi, which do share some of the same frequencies)?
Radio amateurs have been setting up channels (group chats) on some of the VOIP applications to have conversations in pretty much the same way as they would over the air. In fact, you could be mistaken for thinking you were listening to one of the internet linked DMR repeaters or even a QSO on the 80 metre band, but with better audio. Callsigns are given regularly (even the correct regional locator when travelling around the UK), people 'transmit' for 2 or 3 minutes before the next person takes their turn. Channels are moderated to keep them limited to people who have a genuine interest in amateur radio.
Here is one of the most popular channels used for amateur radio talk, mainly in the UK. There are a few alternative channels run by the same people in case the main one is busy. 
At present, over 3000 Zello users have added this channel, and at times there are over 100 connected (95% of those will be just listening, which shows what a nosey lot radio amateurs are, although a 100 person 'net' would be hard work).

Is it going to be the end of 'real' amateur radio?
Probably not, if the hobby was to end, it wouldn't be because of Network Radio.
Listening to the amateur radio channels on Zello, the users are the same kind of people as you would find on any repeater (callsigns from G3 through to M6). As with repeaters, those people will have other interests within the hobby that are related to 'real radio'. Now that weak signal digital modes allow long range contacts that would be impossible using any voice mode, there may be some people who can set up a station which is good enough to work on data modes or CW using limited power or high receiver noise, but struggle to have the voice QSOs they would like. Network radio channels can make up for this missing part of the hobby.
To a complete newcomer though, who had not been used to traditional amateur radio or CB voice contacts, this might not be as important, not enough to attract a younger generation, although it does give them a chance to listen to what they are (or aren't) missing.

But it IS radio, it's using the 800/900/1800/2100/2400/5700 MHz bands!
It is, but there isn't very much you can do to experiment with the transmission and reception on those bands, and it's nothing you can't do with any other mobile phone or Wi-Fi device. As the device always selects the base station with the best signal, unless you were in a very remote area with no normal cellular coverage, experimenting with different antennas or locations would make no difference.
But, as the network radios have external connectors for the cellular antenna, in those remote areas, you could always build a high gain antenna to access a distant 'repeater'.
Apps such as Cellmapper are available to see which base station you are connected to and what frequency that is on, so you can even have a frequency display on your network radio (or phone).
Private LTE (4G) networks are also a thing, at the moment they are only used by some large organisations because of the cost and few available frequencies. The LTE specifications support networks in the 400-470MHz band (but a standard mobile phone won't have any 400MHz radio in it), with narrower bandwidths than used by the public cellular networks (5MHz minimum in the UK). There is also simplex (DMO) LTE communications, without the use of base stations, again this isn't  standard on any phones. Maybe in the future the technology could be easy and cheap enough to use by radio amateurs.
The only gear I've seen for use on private LTE networks is from Huawei, with their eLTE Broadband Trunking System, and for those of you wanting a slightly different 70cm repeater project, try the Rapid Deployment Broadband Trunking System
Huawei's commercial for their network radio system and Rapid Deployment deserves to be developed into a feature length, straight to DVD, movie.




As well as being used for 2-way amateur radio style conversations, the VOIP apps are also useful for remote control or monitoring of your own radio. Zello has VOX so if used with a radio that also has VOX control, you have an simple personal gateway that you can limit to only yourself. It can be used for receive only audio too, there are channels on there which broadcast someone's receive audio while they scan around the bands.

Would I buy a dedicated network radio?
I don't think so, I rarely use radio based repeaters, and spend more time programming in channels for repeaters than I do talking on them. There's always the phone or PC to join in with.

Should you buy one?
Have a listen through the different apps first, that costs nothing. If you find yourself spending time talking, a dedicated network radio might be more comfortable.



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Saturday, 9 June 2018

950MHz 2G Spectrum

Here are some spectrum views of the 900MHz GSM phone band, captured with a SDRPlay RSP-1 and a 1/4 wave ground plane next to an upstairs window (looking north).
My Comet GP-15 tribander on the chimney, with over 25m of coax gave roughly the same signal for a mast which was line of site except for a few trees (the sector facing me is on 959.4). A mast only a few streets away with my best sector on 953.8 was much better on the GP-15 (about 15dB), it's on the opposite side of the house.
Vodafone using 951.4 - 954.8 (18x 200KHz channels 82-99), O2 using 955.2 - 959.8 (24x 200KHz channels 101-124). Most sites are now Vodafone and O2 into the same antennas. It looks like a lot of the newer sites which were built for 3G coverage (usually roadside poles) have been fitted with 2G 900MHz. 2G GSM is nowhere near finished yet in the UK, the cheapest phones are 2G only, and as the turnover of smartphones is faster, support for devices without 4G could be cut down to 2G voice/texts only before too long. 3G capacity is already being cut by refarming the 2100MHz band to 4G for up to 2/3 of the bandwidth. 2G GSM is used by a lot of remote control and slow data applications too, things like tracking devices, digital signage where the speed of sending a txt or GPRS data doesn't matter.
I'm not sure what's happening with the channels like 955.8MHz where the signal isn't continuous, seems to be an extra channel from the same sites.






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Monday, 28 May 2018

FT-8900 Programming Errors

50MHz FT8 was full of stations today around 50.313, all over Europe. Also I had a go on 24MHz with my random bit of wire and 10 watts, made some contacts into Germany and the Netherlands, also received by 2 stations in the UK in the Bournemouth (M1HHL) and Medway (M0OLA) area.

Today I went to the car and connected up my laptop to the FT-8900 to download a new set of memories to it. Using the FTB8900 software as usual, I started off with an upload of the existing settings, and everything was OK. Then when doing the download, it got to the end and then the radio displayed 'clone error' and the software displayed an error message saying it did not receive the final confirmation from the FT-8900.
I was using one of the very cheap USB to serial adaptors which I bought last year, instead of my usual Prolific chip based adaptor (fake chip so need to use an old driver). These new adaptors use a CH340 chip (never heard of it until I plugged one in, expecting a Prolific chip) instead, drivers aren't included with Windows 10.
Well the failed download completely reset the radio, clearing all the memories and other settings. I tried again later, after the temperature had dropped a bit - when I was trying to get the radio to program earlier the car was showing the temperature as 27C and not very comfortable sitting there with a laptop. With the old Prolific adaptor the download worked OK.
I've had trouble with the CH340 cables before, with the WSJT-X software, I had to increase the CAT polling interval from 1 to 2 seconds on a Yaesu FT-847 otherwise it would sometimes get CAT errors.

Downloading to radio - this time it worked

Bargain basement USB-serial adaptor with CH340 chip

Good old Prolific USB-serial, bought at Llandudno Maplin a few years ago

USB device details for the USB-serial adaptors


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Thursday, 15 March 2018

FT8 - 4 Weeks On

I've been using 144MHz FT8 for about a month now, and it's getting more popular. I've been leaving the radio on 144.174 all day while I've been out, and operating remotely using TeamViewer on my phone.
There must be quite a few people doing the same as if I call CQ at any time of day, someone will have received me and there's a spot on PSK Reporter. Because of the extra range of FT8, there's more activity on there now than on 2m FM. Some days I'll put a CQ call out and not get a reply, but it's not a waste of time as I could have been received by someone new.
At the moment conditions on the HF bands aren't very good above 10MHz so it's good that there's something else to do with an SSB radio.

I put a CPC order in today for a few bits and pieces, and ordered some coax adaptors on AliExpress. AliExpress is usually pretty slow (a month or more) but that means it's a nice surprise when something turns up after you've forgotten all about it. One of the things in the CPC order was a dishwasher cutlery basket, but all the others were more electronics related. Ordered 2 optical audio cables as I'd used one for connecting up a sound bar then realised I didn't have any more to connect my PC up to the amplifier.
With CPC, I tend not to use the website to search or browse through the products because the cheapest of anything is usually in the paper catalogue updates I get through my door, or in the PDFs on the website. Most popular things are in the catalogue update, and I like catalogues, it's sometimes better to have a look through pages with pictures and things ordered nicely, rather than a list of search results.
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Thursday, 22 February 2018

VHF FT8

After reading on Twitter that some people were trying the very popular FT8 data mode on 144MHz, I had a go. I don't have anything like a VHF DX station at home, with just a Comet GP15 vertical on the chimney, fed with a bit too much coax.
The frequency for 2m FT8 is 144.174.
I started off using my new SDRPlay receiver and found that I was able to decode a few stations, outside my usual VHF range (G4KUX in IO94 and GM4FVM in IO85).
After connecting up a transceiver, I was able to make some 2-way contacts at this distance, and was even getting reception reports of my signal via PSK Reporter from up to around 300km. This makes the 2m band a bit more interesting, and because data modes software like WSJT-X automatically sends reports to PSK Reporter, even if I'm away from the radio, it's still worth leaving it on all day just in case someone calls CQ.
At the moment, there aren't really any 'lift' conditions on 144MHz, at least not which you would hear if listening to FM or even SSB, and most of the long distance propagation is from reflections off aircraft. Reflections off fast moving objects like aircraft shift the frequency from the doppler effect, and it can be over 100Hz. With FT8, the bandwidth is very narrow, so if there are multiple paths, the same signal can appear on 2 different frequencies. See below for some FT8 activity where there are multiple decodes.

On some days I've received 10 different stations on 144MHz FT8.


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Saturday, 3 February 2018

Because I Hadn't Posted Anything Since Last Year


Happy New Year 2018


 USB load - switchable between 1 and 2 amps

 Barrow BBC MF/DAB broadcast site, is the colinear lower down the mast for smart metering because nothing else is from the site ?

Majority Huntingdon DAB/FM/CD system

New drill

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