I've worked on Auto radios with the variable capacitors and the work good, I believe space was the problem with them ,in my collection of auto radios my favorite is a 1930 Transitone ,it's a TRF with 01A's ! at that time there is no real power supply it uses "B" battery's I've also got a 1931 Transitone 3 that uses 24's for RF amp still a TRF, BILL
