UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Ferrite rod antenna and RF amp for Valve radios

Christoffrad · 7th Oct 2019, 3:34 pm

Thank you for all your further comments. I can report that the MW coil primary is 530uH. I'm currently using a variable capacitor that goes from 30 - 350pf so should resonate between 370 to 1260kHz with this coil. Indeed having introduced the 47R resistor into the emitter ( I also changed to a RF screened output cable) the circuit is now stable but although it exhibits resonance arount the mid MW band when connected to my valve set, it is not possible to detect any reception null as the rod is rotated so I'm not yet happy with this and suspect it may be regeneration from the radio (although proximity between rod/amplifier and radio makes little effect.

Chris

7th Oct 2019, 3:34 pm	#12
Christoffrad Hexode Join Date: Jun 2018 Location: Cambridge, Cambridgeshire, UK. Posts: 262	Re: Ferrite rod antenna and RF amp for Valve radios Thank you for all your further comments. I can report that the MW coil primary is 530uH. I'm currently using a variable capacitor that goes from 30 - 350pf so should resonate between 370 to 1260kHz with this coil. Indeed having introduced the 47R resistor into the emitter ( I also changed to a RF screened output cable) the circuit is now stable but although it exhibits resonance arount the mid MW band when connected to my valve set, it is not possible to detect any reception null as the rod is rotated so I'm not yet happy with this and suspect it may be regeneration from the radio (although proximity between rod/amplifier and radio makes little effect. Chris