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theredhouseinn · 3rd Dec 2019, 5:04 pm

Because the covers are on, the mouse could not get near the base.
I checked the cores, and there was some residual magnetism present, I connected a coil of 28swg across the mains and dipped the cores down the center, result, magnetic flux zero.
Made no difference to the osc..
If I push a ferrite rod down the coil I can tune down to the LF end, no problem.
I am going to try and cut a piece of rod and glue a piece of studding into the end and see if I can eliminate the slug from the equation.
Meanwhile, yesterday, I went through the IF alignment proceedure. It was a long way out, but tuned up ok, giving me a 20dB increase in gain. 20 micro volts into the grid of the mixer gave me an audible signal at the detector. This leads me to think that the 680pf's may be failing in the cans. The crystal phasing was way out, but adjusted ok.
By setting the genny to FM and adjusting the deviation to match the IF bandwidth giving me a perfect envelope on all 4 positions of the bandwidth switch, no adjuustment necessary. I hope.
I have ordered some IO valve bases to construct an external osc cct..
One day I might actually get to listen to some stations on this.
John.

3rd Dec 2019, 5:04 pm	#54
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: RCA AR88D Comms Receiver. Because the covers are on, the mouse could not get near the base. I checked the cores, and there was some residual magnetism present, I connected a coil of 28swg across the mains and dipped the cores down the center, result, magnetic flux zero. Made no difference to the osc.. If I push a ferrite rod down the coil I can tune down to the LF end, no problem. I am going to try and cut a piece of rod and glue a piece of studding into the end and see if I can eliminate the slug from the equation. Meanwhile, yesterday, I went through the IF alignment proceedure. It was a long way out, but tuned up ok, giving me a 20dB increase in gain. 20 micro volts into the grid of the mixer gave me an audible signal at the detector. This leads me to think that the 680pf's may be failing in the cans. The crystal phasing was way out, but adjusted ok. By setting the genny to FM and adjusting the deviation to match the IF bandwidth giving me a perfect envelope on all 4 positions of the bandwidth switch, no adjuustment necessary. I hope. I have ordered some IO valve bases to construct an external osc cct.. One day I might actually get to listen to some stations on this. John.