UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

theredhouseinn · 19th Dec 2019, 3:51 pm

I have been conducting more tests with my osc lashup.
Using the 150v and 6.3v from the set the band 6 coil gives the same result as I am getting in the set.
I used a new valve base and new components and a fm vc with the 3 gangs wired in parallel and an air spaced trimmer in parallel with the 3 pre-sets on the gang.
No osc at the low end using the AR88 cores.
However, using a 1" piece of ferrite rod and the Advance core pushed down the former I can get the coil to tune from 33 meg down to 23 meg with not bad amplitude, but with a bit of a dip in the center of travel.
I think that I have now conclusively proved that I have a frequency dependant slug problem. Unless you prove me wrong??
I eagerly await Rob's coil in the post now for a final test.
Any ideas on how I make my own slugs, iron dust in a clay mix?
There could be, buried in the RCA archives, the spec for maufacturing AR88 slugs.
I find it difficult to believe that I am the only owner of an AR88 with this problem.
John.

19th Dec 2019, 3:51 pm	#95
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: RCA AR88D Comms Receiver. I have been conducting more tests with my osc lashup. Using the 150v and 6.3v from the set the band 6 coil gives the same result as I am getting in the set. I used a new valve base and new components and a fm vc with the 3 gangs wired in parallel and an air spaced trimmer in parallel with the 3 pre-sets on the gang. No osc at the low end using the AR88 cores. However, using a 1" piece of ferrite rod and the Advance core pushed down the former I can get the coil to tune from 33 meg down to 23 meg with not bad amplitude, but with a bit of a dip in the center of travel. I think that I have now conclusively proved that I have a frequency dependant slug problem. Unless you prove me wrong?? I eagerly await Rob's coil in the post now for a final test. Any ideas on how I make my own slugs, iron dust in a clay mix? There could be, buried in the RCA archives, the spec for maufacturing AR88 slugs. I find it difficult to believe that I am the only owner of an AR88 with this problem. John.