SPECTRUM COMMUNICATIONS

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AERIALS, TRAPS, & CABLES

19 August 2020

Proprietors;- Mr A.J. Nailer HNC BA G4CFY, Mrs J.R. Nailer. 

12 WEATHERBURY WAY, DORCHESTER, DORSET, DT1 2EF, ENGLAND

Phone UK 01305 262250 International 0044 1305 262250

Please email or phone for a quote or for a Paypal money request or for bank details. Payment can be by direct bank transfer or by credit/debit card or via Paypal to g4cfy@spectrumcomms.co.uk  together with a note stating product required. Purchase of several items is likely to make a saving on postage. You can also obtain products by using my Ebay shop https://ebay.co.uk/str/Spectrum-Commsand pay via Paypal.

Orders & quote requests to  jean@spectrumcomms.co.uk

Technical queries to  g4cfy@talktalk.net

         CONTENTS

Coax cables Balun 1-42MHz Air cored (RX & TX) Active Wire Aerial (RX)
95 Ohm Twin Feeder Slim-G VHF (RX & TX) Nomad VHF/UHF (RX)
G4CFY Traps Flexi-whips VHF/UHF (RX & TX)  Active Nomad VHF/UHF (RX)
G4CFY HF Trap dipoles (RX& TX) Mobile Whip Aerials VHF/UHF (RX/TX) Compact Coil HF Active Aerial (RX)
Inverted-L HF (RX & TX )  G4CFY Aerial Development History Long Wire HF portable aerial (RX)

 COAX CABLES

RG213; 50 Ohm. High quality Cabnex 213 cable from Nevada with 7 strands of 20swg (0.035") plain copper centre core and plain copper braid with estimated 85% coverage.  Solid polyethylene dielectric with a 66% velocity factor.  Outside diameter 10mm.  Suitable for use with RG8 N type plugs and PL259/9.  £1.60/metre + P&P at cost.

RG Mini 8; 50 Ohm. High quality Nevada cable with 19 strands of 32swg (0.011") plain copper centre core and plain copper braid with estimated 85% coverage. Low loss foam polyethylene dielectric with a velocity factor of 80%.  Outside diameter 6mm.  Uses plugs with 7mm braid entry, such as PL259/7.  Can be used with BNC plugs and also with RG58 N type if rear nut is drilled out 1/4". 99p/metre + P&P at cost.

RG58C/U; 50 Ohm. High quality Webro cable with 19/0.18mm (36swg) tinned copper centre core and tinned copper braid with 90% coverage. Solid polyethylene dielectric with a 66% velocity factor. 100pF/metre, outside diameter 5mm. 75p/metre + P&P at cost. 100m drum £75 including carriage.

URM76; 50 Ohm. High quality Webro with 7/0.32 plain copper centre core and plain copper braid 87% coverage.   Solid polyethylene dielectric with a 66% velocity factor. 100pF/metre, outside diameter 5mm. 70p/metre + P&P. 100m drum £70 including carriage.

RG174A/U; 50 Ohm. High quality with 7/0.16mm tinned centre core and heavy braided tinned copper screen.  98pF/metre, 2.8mm diameter.  75p/metre + P&P at cost. 

LOW Z, LOW TVI, LOW NOISE, TWIN FEEDER

TWIN FEEDER, 95 Ohm, 2kW rated. 24/0.2mm cores individually polyethylene sleeved with an overall sheath of polyethylene. Cancels near field so doesn't emit an electromagnetic field and won't cause TVI.  Both cores pick up the same noise so there is no noise differential between them and so much quieter than coax.  Loss is the same as RG58U at 0.04dB/m at 10MHz. Price £1/metre, postage at cost.  Replacement 21m length for full size G4CFY/G2DYM dipole, with ends made-off £25.00, plus £3.50 P&P.  

 

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ANTENNA TRAPS

NEW LITE TRAPS for 10m, 20m, 40m, 60m, & 80m.

Produced to satisfy the requirement for lighter weight traps.  Probably the lightest traps on the market weighing just 40gm (1.1oz), 51gm (1.5oz), 72gm (2.0oz), and 90gm (2.6oz)respectively.  The new design concept has made it possible to produce the long awaited 80m traps.  The maximum power rating is the legal limit of 250W continuous 400W unprocessed peak power.

Prices each 10m £24.00, 20m & 30m £25.00 each, 40m & 60m £27.50 each, 80m £30.00. Hermes carriage on single £4.50.  Hermes carriage on pairs £6.00.

 

G4CFY TRAP DIPOLES

The picture opposite is the G4CFY 80/40M Trap dipole with 6sqmm top wires, the new Lite Traps and 21m of 95 Ohm twin feeder.  The feeder must be used with a 1:1 balun or balanced ATU in the shack.

The low impedance twin feeder allows differential mode signals on receive and transmit to travel along the feeder without a measurable emitted electromagnetic field.  On receive identical noise is picked up on both cores giving almost no differential feeder noise at the rig.  It is so quiet using this feeder that at first you might think the aerial system is faulty.   

If you want the bands 80, 40, & 20m then the best aerial will be the LTD80/40/20m, and 2.52mm wire will do just fine.

Prices below give a choice of 2.52mm or 62mm top wires and include tracking and insurance by Hermes in UK.

TYPE BANDS LENGTH 2.52mm  62mm
LTD40/20m 40 20 15m 52ft 6" £131.50 £143.00
LTD40/20/10m 40 20 15 10m 45ft £185.60 £197.75
LTD60/30m 60 30 10m 71ft £135.75 £155.00
LTD80/40m 80 40 17 15m 103ft £148.50 £172.75
LTD80/40/20m 80 40 20 17 15m 90ft  £204.25 £226.50
LTD160/80m 160 80m 197ft £177.50 £223.00
LTD160/80/40m 160 80 40 17 15 10m 168ft £236.75 £276.50

 

INVERTED-L AERIAL

These Spectrum Lite Trap Inverted-L Aerials are essentially half a trap dipole with the feedpoint at ground level.   Another way of understanding its operation is as a loaded quarterwave Marconi vertical with the radiating element bent over.

The aerial is fed via coax to a coupling box secured to an earth stake at the far end of the garden. There is then a near vertical section, as high as you choose, and the remainder is near horizontal back towards the house.   Because it is coax fed it is much noisier than the twin fed trap dipole.  To work efficiently it requires a good ground.

Supplied in 2.52mm or 62mm PVC covered wire and with the coupling box and U-bolts.

TYPE BANDS LENGTH 2.52 mm  62 mm 
LIL80/40m 80 40 17 15m 51ft 6" £77.00 £89.10
LIL80/40/20m 80 40 20 17 15m 44ft 10" £103.75 £114.80
LIL160/80m 160 80 17 10m 102ft 6"  £91.50 £106.80
LIL160/80/40m 160 80 40 17 15 10m 89ft 10" £118.00 £133.60

Prices include tracking and insurance by Hermes in UK.  EU & World prices are available on request.

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BALUN 1:1 RATIO

This air cored balun is only a slight variation on that of Richard Holman G2DYM and 2 of them back-to-back give a flat response between -1dB points from 1.8-42MHz.  Experiments using toroidal cored designs by well known authors in Rad Com, such as the late Peter Dodd G3LDO, fail to produce anything like such a low loss flat response over such a wide range.  

The screen shot opposite of the back-to-back test has 0dB three divisions down from the top and each vertical division is 10dB.  The horizontal scale is 5MHz per division and you can just see that the response rises up near the white line on the left at about 1/5th of the first division (1MHz) and has dropped again to -1dB at the right of the 6th division across, that is 30MHz.  It continues with a slight dip to -2dB and rolls off again about 1/5th across the 9th division (40MHz).

G2DYM rated the balun at 1kW but I had one fail at less due to thin enamel insulation so I switched to 3 different types of coloured enamel  It looks much nicer too. It might now survive 1kW again but I conservatively rate it at full legal power of 400W on SSB and 200W continuous.  It is to be used in the shack between the end of the 95 Ohm twin feeder and an ATU/RIG. Price £40.00, carriage £5.00.

 

 

G4CFY Aerial Development History  Link

SLIM G TX & RX AERIAL. Manufactured for either 156MHz Marine band, or 145MHz 2m (Amateur) or 127.5MHz (Airband). This was previously called the GAREX JIMP and is essentially  a portable version of the Slim Jim described by G2BCX in PW April 1978.Actually the aerial described as a J pole is really a misnomer as it really is a squashed letter G, hence the new name.   It is ¾ of a wavelength long at the manufactured frequency and achieves a gain of 1.8dBd, which is 12dBd (15 times) better than a 15cm rubber duck. The main element is fabricated using 300 Ohm twin feeder with a matching stub in a watertight housing 4" (10cm) long. There is 4m of coax cable with a choice of BNC, or PL259 connectors. The 156MHz version is 1.3m long, the 2m version is 1.4m long and the 127.5MHz version 1.6m long and all fold down to 20cm. Weight is just 250g (9oz). Price £22.00 UK, £25.00 EU, £28.20 World.  EU & World tracking £5.50 extra.

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FLEXIWHIP FOR HANDHELDS   These are made using a nylon tube and are fully waterproof and rugged. Solutions have been developed to allow the aerial to be supplied with a wide variety of plug or socket connectors.  The maximum production length is 50cm, so for frequencies below 140MHz they are made as loaded quarter-wave aerials, and above that frequency they are full quarter wavelengths.

Flexi-whips can be custom manufactured for any frequency in the range 68-418MHz, and the 2m (144MHz)version is normally made and trimmed as a dual band, quarter wave on 144MHz and three quarter wave on 433MHz.

A loaded 4 metre Flexiwhip can be made 50cms long and is -6dB relative to a full length 1/4 wave whip. The loaded 4m Flexiwhip will give 12dB more gain (that's 2 S-points) than a 12.5cm rubber duck. Connector options are BNC plug, SMA plug, SMA socket, TNC plug, PL259.

FLEXIWHIP. Prices including carriage: Updated 15 August 2020.

Frequency band Length cm UK & EU World
68-88MHz loaded, 4m and PMR 50 £22.50 £25.25
118-137MHz loaded, airband 48 £22.50 £25.25
118-137MHz loaded, pilot airband 38 £22.50 £25.25
144/433MHz unloaded 1/4 & 3/4 wave 50 £18.50 £21.25
156-162MHz full length, marine band 45 £18.50 £21.25

Flexi-whip for Wouxon KG699E 4m Handheld, 51cm long and supplied with SMA socket, £24.00.

Flexiwhip for ICOM E90 4m handheld, 51cm long and supplied with SMA plug, £24.00.

2m/70cm dual band Flexi-whip for Wouxon, 49cm long with SMA socket, £20.00.  

2m/70cm DUAL BAND MOBILE WHIP.  This is a centre loaded whip with antiphase coil so the full 46cm length corresponds to 1/4 wave on 144MHz giving 0dBd (2.15dBi) gain.  The antiphase coil allows the top section to be in-phase with the bottom section on 70cm to provide 3dBd (5.15dBi) gain.  Robust and reliable ferrules connect the 17/7PH whips to the antiphase coil and the assembly is solid moulded in nylon. The aerial is supplied with a 3/8" UNF stud, or with a PL259 and includes a protective plastic tip.   Price £24.00 including carriage.

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QUARTER WAVE WHIPS.  These are cut from 2.54mm diameter 17/7PH stainless steel to suit any centre frequency in the range 68 to 450MHz.  They are supplied with a hinge adapter, or a 3/8" UNF stud, or even with a PL259 and all include a protective plastic tip. 1/4 wave whips in the range 68-90MHz are two sections which screw together. Priced at £12.50 each including carriage.   1/4 wave whips 90-450MHz are single section and are £10.00 including carriage.

RECEIVE-ONLY AERIALS

NOMAD WIDEBAND PORTABLE SCANNER AERIAL 25-500MHz. The aerial element is made from 300 Ohm feeder configured like a Slim Jim, with modified stub matching to give greater operational bandwidth. It is intended to be portable but can be used as a permanent aerial in places where conventional wire aerials cannot be used. The overall length is 1.4metres with a matching stub housing 6" (15cm) long and folds down to just 25cm (10").  It is fitted with 4m of 50 Ohm coax cable with a BNC male connector as standard, but can be supplied with PL259.  For better reception of Air-band, 2m Amateur band or Marine-band use the Slim-G detailed above.Price £22.00 UK, £25.00 EU, £28.20 World.   EU & World tracking £5.50 extra.  

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ACTIVE NOMAD WIDEBAND SCANNER AERIAL 25-500MHz. Now with a new MMIC amplifier giving a flat gain of 10dB from HF to UHF. Overall length 1.4m. Ideal for loft or portable use. Includes 4m of coax cable.  DC/RF combiner box with provision for 9V PP3 battery, or external 12V supply. 0.6m patch lead with choice of phono, BNC, or PL259 connector for receiver. Price £48.00 UK, £55.00 EU, £59.00 World, including tracking. 

New version with Mains Adaptor £63.50 UK, £73.75 EU, £80.25 World, including tracking.

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COMPACT COIL ACTIVE HF AERIAL.   500kHz to 30MHz. Ideally suited to permanent installation in marine environments and where other wire aerials would be unacceptable. The Antenna is a 420mm PVC cylinder with saddle type mounting bracket and 7 metres of high quality RG58 cable terminated with an RCA Phono plug.  The end caps are force fitted and the cable entry is through a waterproof gland.  The aerial is a further evolution of the original Compact HFAA sold by Garex Electronics and NASA Marine and as standard gave a gain of 20dB up to 14MHz then falling steadily to 0dB at 28MHz.  The Compact Coil Aerial contains an amplifier with 20dB gain at band edges of 500kHz and 30MHz with 24dB in the middle of the band.   The DC version works in conjunction with a DC/HF combiner (sometimes referred to as a bias-T) that has a BNC socket for connection to the receiver and a DC 2.1mm chassis plug for connection to an external 12/13.5V supply.  It comes with an 0.6m red/black DC cable to connect between the adapter and a supply of 12/13.5V with a current of up to 20mA and also a 0.6m BNC to PL259 cable to the receiver.  The Mains version works in conjunction with a Mains/HF combiner (sometimes referred to as a bias-T) has a BNC socket for connection to the receiver and a 1 metre cable with UK mains plug.   It also comes with a 0.6m BNC to PL259 cable to the receiver.  

Compact Coil DC, £48.00 UK, £58.00 EU, £62.00 World.   Compact Coil Mains, £71.00 UK, £81.00 EU, £87.00 World. Price include tracked carriage.

 

ACTIVE WIRE AERIAL. An active aerial for VLF to 30MHz and ideal for locations where an outdoor aerial is prohibited. The aerial is wire 5 metres long with 4 washers to allow it to be pinned to the wall or ceiling.  It comes with a mains powered wideband amplifier with 15dB gain, flat across the band. Also included is a 1.2m BNC to BNC, or BNC to PL259 patch lead.  Price £48.00 UK, £54.00 EU, £56.50 World including tracking. 

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LONG WIRE PORTABLE AERIAL for receiving 2-30MHz.   It comprises 14m (46ft) of PVC covered wire together with a 2m length of thicker PVC wire with a crocodile clip to provide an earth. The two wires are joined to a short length of coax cable with a PL259 or BNC connector. An SMA connector version is available for £1.00 extra. Price £12.50 UK, £13.25 EU, £15.50 World.  EU & World tracking £5.50 extra.

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