ECF82 frequency changer - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

m0cemdave · 10th Oct 2019, 9:47 pm

Quote:

Originally Posted by turretslug

Then the RA17 came along.... and both hands needed to dart around again. I wonder what US oppoes who were accustomed to the contemporaneous R390 with its complex but thorough ganging arrangements thought of it.

I think it may depend on whether a receiver is expected to be used for General Search (i.e. tuning around fishing for signals), or point to point communcation where it is set to a frequency and left there for long periods of time.

Herald1360 · 11th Oct 2019, 11:35 am

Tuning around was easy with an RA17 with preselector set to wide band. OK, you had to change "band" every 1MHz but that was easy too. STAYING on tune forever (nearly) after being set to a fixed frequency was its party trick. If there was serious noise or adjacent channel crap you could switch in the preselection and peak it by ear.

Neutrino · 11th Oct 2019, 12:57 pm

This circuit of a typical television tuner for Bands I and III does not appear to explicitly show a component coupling the oscillator and pentode:

http://www.r-type.org/articles/art-011.htm

However, the way it is drawn suggests inductive coupling between the oscillator and RF tuned circuits. Perhaps this was lost when the circuit in the RSGB handbook was drawn.

David

11th Oct 2019, 11:35 am	#22
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: ECF82 frequency changer Tuning around was easy with an RA17 with preselector set to wide band. OK, you had to change "band" every 1MHz but that was easy too. STAYING on tune forever (nearly) after being set to a fixed frequency was its party trick. If there was serious noise or adjacent channel crap you could switch in the preselection and peak it by ear. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O Last edited by Herald1360; 11th Oct 2019 at 11:43 am.

11th Oct 2019, 12:57 pm	#23
Neutrino Pentode Join Date: Oct 2016 Location: Maldon, Essex, UK. Posts: 182	Re: ECF82 frequency changer This circuit of a typical television tuner for Bands I and III does not appear to explicitly show a component coupling the oscillator and pentode: http://www.r-type.org/articles/art-011.htm However, the way it is drawn suggests inductive coupling between the oscillator and RF tuned circuits. Perhaps this was lost when the circuit in the RSGB handbook was drawn. David Attached Thumbnails