[Texasrocker]

You most probably found a (partial) vintage tube type Radio "outdoor longwire antenna kit"! The porcelain insulators (usually 2 included, were to string uninsulated wire between points from house out to a tree, or another outdoor building strung horizonally high above ground level as possible). These type vintage antenna *kits*, come up for sale on eBay from time to time. The outdoor longwire antenna-kits were originally sold as many vintage radio brands of the 20s- late 1930s required them to be connected to the radios ant terminal to get reception. Many sets back in those days didnt have a factory balanced "built-in" factory loop antenna as the later sets of the 1940s-50s-60s tube type radio receivers. The *condenser* in tar in your kit, was to be used to keep the sometimes "excessive-lengths" ,... of stung outdoor antenna wire from *overloading* the chassis antenna input capacity! Some vintage radio sets required more outdoor antenna length than others ( rural farm areas,etc), depending on how far the listeners were from the Radio Station Transmitters during those days!!
Hence, if you lived in NYC back in 1920/30s era, with a fairly powerful AM station(s) a few miles away , the capacitor would come in handy indeed!! Otherwise, not using the added condenser in *tar* would allow some listener in the middle of farm land in Nebraska, to use the longwire antenna to hear NYC also at night!
And of course, outdoor longwire antennas were most definately required to receive Shortwave Bands reception on the many vintage tube radios sets of that era that offered a SW band listening also.You can also bet if it has the name Philco stamped on it, it is very high quality outdoor LW antenna insulator indeed!! Randal