Saturday, 29 December 2018
DATA Socket
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.
Thursday, 25 October 2018
September
https://t.co/xJ4z4yrFQa bad news if Android loses decent WiFi scanning, at least my current phone is still at version 7
— Simon M1AVV (@m1avv) September 5, 2018
#SnapOnAir #lora walkie talkie with @ESP32net and #OLED display is fully tested and working on 868mhz. pic.twitter.com/e5ScKbTJF2
— pwav robot (@pwavrobot) September 4, 2018
It looks like the new Yaesu FT-4X is after all just a Baofeng. But better ! https://t.co/AKHHuYaOTX
— Razvan Fatu (M0HZH) (@YO9IRF) September 5, 2018
It's never too early for an Xmas tune https://t.co/nsDMIdQQiC
— Simon M1AVV (@m1avv) September 17, 2018
Switching ISP after 15 years, upgrade from TG582 (2.4g only, separate VDSL modem) to TG589vac. Set guest network to old SSID and password so no fuss when swapping router next week pic.twitter.com/xRKzSFY5UT
— Simon M1AVV (@m1avv) September 21, 2018
Poundworld was always good for music pic.twitter.com/qhASSMA29j
— Simon M1AVV (@m1avv) October 2, 2018
Think I've done a bit much remote FT8 pic.twitter.com/qubVcFQJgJ
— Simon M1AVV (@m1avv) October 5, 2018
Nice weather, 2GHz tropo, LAC 1245 = SW Scotland? I should have a network radio to work the DX 📻 pic.twitter.com/0ACYyvMHPZ
— Simon M1AVV (@m1avv) October 10, 2018
GDRP - not a good start pic.twitter.com/JyNU59QN4Y
— Simon M1AVV (@m1avv) October 14, 2018
August
https://t.co/7vjq79CSwo noisy car USB charger. I thought there was something up with the radio in the car
— Simon M1AVV (@m1avv) August 11, 2018
Onn (Asda) power bank, delivered 4.36Ah at 5v 1A. Rated 6700mAh (battery)/24.12Wh so not bad pic.twitter.com/rho3Kl1r5Q
— Simon M1AVV (@m1avv) August 11, 2018
Vodafone masts, 90s analogue network in Lancaster/South Cumbria pic.twitter.com/1Sup9XTvC6
— Simon M1AVV (@m1avv) August 12, 2018
100MHz band stop filter (25db cut in 95-100 MHz) makes a big difference to Baofeng handie on 145MHz. pic.twitter.com/q4RxbhsYpk
— Simon M1AVV (@m1avv) August 12, 2018
Someone in the car park must be watching Borat in their car with FM tx, put radio on 87.5 and there he was
— Simon M1AVV (@m1avv) August 14, 2018
Always a nice surprise when something finally arrives from AliExpress. Delivery long enough to forget you ordered anything if it's cheap enough pic.twitter.com/f3kCjybAr0
— Simon M1AVV (@m1avv) August 18, 2018
Moved FT-7900 into the car pic.twitter.com/qE7TzQ9n8G
— Simon M1AVV (@m1avv) August 25, 2018
Phil Mitchell running Windows Vista on his laptop. Sort it out Phil, just install Linux Mint or something
— Simon M1AVV (@m1avv) August 30, 2018
Tuesday, 23 October 2018
Payphones
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
Friday, 10 August 2018
Vintage Vodafone Mast
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.
Monday, 30 July 2018
Network Radio
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.
Saturday, 9 June 2018
950MHz 2G Spectrum
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.
Monday, 28 May 2018
FT-8900 Programming Errors
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
Thursday, 15 March 2018
FT8 - 4 Weeks On
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.
Thursday, 22 February 2018
VHF FT8
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.
Saturday, 3 February 2018
Because I Hadn't Posted Anything Since Last Year
Happy New Year 2018
Majority Huntingdon DAB/FM/CD system
New drill