[Heathkit] SB-220 Problem

[Larry Boekeloo]

I have an SB-220 that I purchased a few months ago and just got around to putting it on the air last night.  When I connect the RF cables, the receive in my Yaesu is gone as though there is a short in the coax.  These are exactly the same coax jumpers I use on my SB-200 so I know they are good.
   
  Any ideas what may be causing the "short" so I don't have any receive?  I thought I would go to the list before I tore into it.
   
  Thanks.