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WME_bill · 22nd Mar 2018, 4:14 pm

FET for D54.
I am a bit nervous at offering you something which is not exactly a metal cased 4 lead FET,as you seem to be concerned about finding the original types for something made nearly 40 years ago, in spite of lots of alternatives still available from second rank manufacturers in USA or India or China, via ebay or similar. I see from about £1.50 upwards each. Lots of BF245, 2N3823, 2N5245.Even a single UC734 at £5.00.
To save you the effort of searching, I will gladly send you for the postage cost two UC734, TO18 FET, with 3 leads. The fourth lead has been chopped off.
I have chosen two from my stock which are fairly closely matched:
no 17, Idss 10.5ma, Vp 3.3v, Gm 5.1
no18, Idss 9.8ma, Vp 3.1v, Gm 5.3
They came I think from some RACAL counter/voltmeter panels.
Telequipment are not going to buy closely matched pairs, as it would have been too expensive, so they provide a setting up adjustment with the preset balance control in the circuit, so that differences in standing current can be taken up.
The manual tells you how to adjust this is you are in doubt.
Send me a private message with your name and mail address so we can discuss.
wme_bill

22nd Mar 2018, 4:14 pm	#16
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: Telequipment D54 ? FET for D54. I am a bit nervous at offering you something which is not exactly a metal cased 4 lead FET,as you seem to be concerned about finding the original types for something made nearly 40 years ago, in spite of lots of alternatives still available from second rank manufacturers in USA or India or China, via ebay or similar. I see from about £1.50 upwards each. Lots of BF245, 2N3823, 2N5245.Even a single UC734 at £5.00. To save you the effort of searching, I will gladly send you for the postage cost two UC734, TO18 FET, with 3 leads. The fourth lead has been chopped off. I have chosen two from my stock which are fairly closely matched: no 17, Idss 10.5ma, Vp 3.3v, Gm 5.1 no18, Idss 9.8ma, Vp 3.1v, Gm 5.3 They came I think from some RACAL counter/voltmeter panels. Telequipment are not going to buy closely matched pairs, as it would have been too expensive, so they provide a setting up adjustment with the preset balance control in the circuit, so that differences in standing current can be taken up. The manual tells you how to adjust this is you are in doubt. Send me a private message with your name and mail address so we can discuss. wme_bill Last edited by WME_bill; 22nd Mar 2018 at 4:20 pm.