[AMRadio] Heath RX1 Mohawk info

[CL in NC]

After around 20 years of use, I put my Mohawk on the bench as it was getting a bit anemic.  This RX was  rescued as it was getting put into the trunk of a car by a man who's dad built it in the '50's and just listened on it, never getting a ticket.  The dad passed on and the son didn't want it.  I did go through it way back then, finding bad filters and coupling caps, cleaning up solder joints and doing a complete alignment, and the only failure I have had since then is the 6BJ7 detector tube, one filament went out of the 3 in the envelope.  Of course it was the detector section, not the AVC or ANL where I might have skipped it for a while before removing it from the bottom of the pile of gear on top of it and removing all the screws. With that said, I found an issue with 80 meters that I neglected way back when, but became evident that something was wrong on 80 compared to the other bands.  I did find the addendum for the prebuilt front end, but it doesn't show a complete schematic either, just a reprint of the RX1 manuals version.  I found an 82pf across the 80 meter antenna coil, which made the coil tuning mushy and the ant. trimmer not very effective.  When I removed it, sensitivity went up greatly, and the ant trim did it's peaking job like it was supposed to.  Does anybody know if there is supposed to be a cap across the 80 meter antenna coil, and also across the 40 right next to it?  The 40 meter cap is a 100pf unit, with color dots, while the one on 80 is the more modern with writing and the coded 820 for 82 and no zeroes. If it is supposed to be there, is is an 82PF? The parts list for the front end does not show these caps listed, the cap list is rather short, at first thinking they listed only the parts drawn on the addendum, but they do list all the coils, even though most are not shown. Also, if anybody has any suggestion on why the converter band has poor sens and breaks into oscillation,  that would help too.  15, 11, 10, no problem, with factory spec sens and no instability,  but the convertor band is a mess.  I was checking the tubes, and put one of the 6CS6's in the tester and turned it on, it got so bright at the bottom, thought I had left the filament in 12.6.  I looked closer, and where the filament goes into the cathode, a bunch of the coated wire was in a big knot right at the bottom of the tube and lit up like a light bulb.  It is a Raytheon 1958, and checked just fine too.

Charlie, W4MEC in NC