GW4ALG's 136 kHz Pages

[ GW4ALG went QRT in February 2007 ]

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Ring Cores for transformers
Ferroxcube (formerly a Philips Components company, now part of the Yageo Corporation) produce a range of ring cores to the 3C90 Material Grade Specification.   This appears to be an excellent alternative to the '3C85' material (now discontinued), which was originally popularised for LF power applications by David Bowman G0MRF.  The Philips 3C85 Material Grade Specification (now archived) provides all the information that you will need about this material.

For a time, some sizes of the 3C85 ring cores may still available in the UK from Arrow Electronics (UK) Limited, Edinburgh Way, Harlow, Essex, CM20 2DF. Tel: 01279 626777 (or +44 1279 626777).

Material OD/ID/Height (mm) Philips Part Number Arrow Stock Number
3C85 25/15/10 4330-030-34480 058377R
3C85 42/26/12.5 4330-030-35520 420604R
3C85 58/40/17.5 4330-030-35530 420605G

The 25 mm OD core is often used in inter-stage transformers up to 40 W RF.  The 58 mm OD core remains cool at 500 W RF, and has been used successfully in PA output transformers at 1000 W RF. 

Another major supplier of Philips ferrite products is Hawnt Electronics, Birmingham, UK.  Tel: 0121 784 2485 (+44 121 784 2485), or Fax: 0121 783 1657 (+44 121 783 1657).

The 3C85 and 3C90 cores are not suitable for use as high power inductors.  They get very hot when used as low pass filter coils in LF transmitters!

Ring Cores for inductors
Micrometals make a range of dust iron cores, including cores suitable for use in inductors at 136 kHz.  Such cores are red in colour and carry a '-2' suffix,    They are available in the UK from: Sycom, PO Box 148, Leatherhead, Surrey, KT22 9YW   
Tel: 01372 372587    Fax: 01372 361421

Part Number OD/ID/Height (inches) AL Value (uH/100 turns)
T130-2 1.300/0.950/0.437 110
T200-2 2.000/1.250/0.550 120

The T200-2 core has been used successfully in low pass filters at 100 W RF.  An upper power limit for this component in this application has not yet been determined. Observations from other experimenters would be appreciated.


High Current Capacitors
Philips Components make a range of '378-series' capacitors suitable for use in power amplifiers; low pass filters; and for matching LF transmitting loops. These capacitors are available in the UK from Arrow Electronics (for contact information, see above).

Value (uF) Voltage (Volts) Philips Part Number Arrow Stock Number
0.0033 2000 37892332 056343F
0.0047 2000 37892472 056344D
0.010 2000 37892103 056345B
0.015 2000 37892153 056346X
0.047 1600 37882473 056341X
0.1 1600 37882104 056342H

10 m Fibre Glass Pole
The telescopic pole used to support my 12 m experimental vertical is marked:
WALTER SPIETH, DK9SQ, 73061 EBERSBACH, Tel: 0 71 63/59 68
The pole was purchased in England from Sycom (Syon Trading), 16 The Ridgeway, Fetcham, Leatherhead, Surrey, KT22 9AZ. Tel: 01372 372587 (or +44 1372 372587).