5314027865

54

THE S H O R T W A V E MAGAZINE

March, 1980

S.E.M.

P O. BOX 6, CASTLETOWN, ISLE OF MAN Tel: MAROWN [phone]

Pre-Amplifiers, Power Amplifiers, Converters, Transverters,

A.T.U.s — Something for E yery one

2.    PA5 AUTOMATIC 2 METRE PRE AMPLIFIER

Same as the Sentinel Auto but for 240V mains operations in a pretty little case. Size: 3$ x 6ł front panel. 2ł deep. S0239 sockets. Prlce: £28.75 ex. stock.

3.    SENTINEL STANDARD 2 METRE PRE-AMPLIFIER

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Same performance as the Sentinel Auto but no r.f. switching. Price: £13.22* ex. stock. 70cmsversion £20.90* ex. stock.

PA3 DUAL GATE MOSFET 2 METRE PRE AMPLIFIER

Mini 2 metre pre-amp. Size 1 cubic inch to fit inside transceivers. N.F. 2dB gain 18dB. 9-15V. £8.00 ex stock. 70 cm version £10.00 ex. stock.

S.E.M. Z MATCH

This Circuit is generally accepted as being the most VERSATILE transmatch system.

It will match aerials of 15-5000 Ohms, to your equipment. BALANCED or UNBALANCED at up to 1kW. SO 239 and 4 mm terminals for co-ax or wire aerials, both end fed and open wire. Price: £45.00. Ex stock.

SENTINEL H F. WIDEBAND PRE-AMPLIFIERS

2-40MHz, 1 5dB gain. Ideał units for pepping up receivers on 15 and 10, for OSCAR reception and as an ACTIVE AERIAL. 9-12V supply. Size: 2\ x1y x3. We make the following two versions:

THREE SENTINEL 2 METRE POWER/PRE-AMPLIFIERS

Ali are linear, ALL MODES. Switch straight THROUGH on receive. R.F. switching switches at. 1 watt. Latest SWR protected power transistors. Receive J FET selected for IdBN.F. 18dB gain. same Circuit as Sentinel N/.H.F. pre-amp (see below) S0239 sockets.

SENTINEL 30 Ten times power gain. e.g. 3Win 30Wout. Upto 5 watts input. £50.00.

SENTINEL40— Four times power gam, e.g. 10W in 40W out. Up to 16 watts drive. £66.70.

SENTINEL 100 - Ten times power gain. e.g. 10W in 100W out. Up to 16W input. £126.50. Ali in stock.

SENTINEL 2 METRE PRE-AMPLIFIERS

The 2 metre units use a neutralised J. FET Circuit rather than the morę common MOSFET or grounded gate J FET. This gives lower noise figures and higher gam. We select the J FETs for a 1dB noise figurę and 18dB gain.

The noise figurę of 2 metre receivers is usually 7 8dB and to overcome this noise we find the 18dB is necessary. We use 18 s.w.g. (1.22 mm) air spaced coils for high Q. These are both efficient and selective.

SENTINEL STANDARD H F. PRE-AMPLIFIERS

Performance as above. £10.00* ex. stock.

SENTINEL AUTO H F. PRE AMPLIFIERS

Same performance as above with a change over relay operated by your transceiver relay for direct connection in your aerial co-ax. £14.95* ex stock.

S.E.M. FORWARD/REFLECTED POWER METER

500W 1-30MHz. Separate pick up unit £29.17 ex stock. Separate pick up unit £29.17 ex. stock.

S.E.M EUROPA C 2 METRE TRANSVERTER

200W input. 2dB N.F. Plugs straight into Yaesu equipment for any modę 2metre use. £126.65. Repeater shift £15.00. CPS10 for use with other equipment, £57.57 ex stock.

CONVERTERS

SENTINEL 2 metre converters: IFs, 28-30MHz. 4-6MHz. 2-4MHz. 2dB N.F. 30dB gain. £23.00 ex stock.

SENTINEL X 2 metre converters same as above with internal mains supply — £26.50 ex stock.

SEM 70 70 cms to 2 metres — £23.00.

SENTINEL TOP BAND CONVERTER £20.80. Ex stock.

We have three models for your choice.

1. SENTINEL AUTO 2 METRE PRE-AMPLIFIER

For connection straight into the aerial lead and the r.f. switch changes over automatically between transmit and receive on any modę. See above for morę detail. 12V nominał. Size: 1J"x2*~x4'. Price: £20.00* ex. stock. 70 cm version £23.00* ex stock.

Prices include VAT anddelivery. *Belling Lee sockets standard, S0239s £1.73 extra. 12 months guarantee. To order: C.W.O. or credit card. Phone your credit card number for same day service. Belling Lee Plugs 25p. PL259 pług and reducer 75p.

Need morę info? Ring or write.