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Old 11th Feb 2009, 6:28 pm   #1
Pete_kaye
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Join Date: Jun 2005
Location: Sheffield, South Yorkshire, UK.
Posts: 1,227
Default Jonell radio problem.

I am working again on a Jonell radio which is very similar to a 1952 Ace A50/1 ie same valves but slightly different layout.The original thread has gone.
There is only one problem ,weak on LW but good on Mw and SW.It has no internal aerial and a shortish 8' aerial will bring in lots of stations but only a squeak on Lw with 2 strong MW stations around the 900m mark just audible.If I connect to an attic aerial of 40'+,then Lw comes through quite well(R4 ,RTI daytime +2 French) and the others very well.What is this indicating?
I have measured the voltages on the first 3 valve top caps and this altered the tuning slightly and dropped the volume on V1 and V2 only;the readings were -.4V (V1/2) on Mw and -2V on V1 and-0.4 on V2 (LW).On V3 it was always zero.
Touching with my finger just gave a buzz on all three.Can someone explain these results and what might be causing the poor LW.
It is all original underneath.I have located 3 banks of trimmers (6 in all) and 6 associated coils but not sure which is which.Minor adjustment to 2 trimmers will move the Lw stations around but not improve volume.
Am I right to think that a short aerial should have been enough originally?
ps I have connected chassis to mains Earth(AC onlyset)
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