[ICOM] Another Icom 740 question

[William Lambing]

John, as Frank (W3UHF) noted, the cure is to do the mod.  When I had mine, I never used the preamp anyway, so it did not matter.  For HF, about all a preamp does in increase intermod.

Once crud builds up on relay contacts, any kind of spray does little to remove the crud.  Plain old typing paper does better.  HP had an article some years ago about using ordinary bond paper as a cleaner for relay contacts.  If you look at this stuff under a photomicrograph, you will see it looks like craters of the moon.  It is a very fine abrasive.  It does work.  We did this on open frame relays for avionics stuff.  The black stuff you see on the paper is the crud from the contacts.

73

Bill, W0LPQ