Metrologist,
What is/does the connector (go to)?
The two pins 4+5 of the RTL chip are a balanced differential input and quite sensitive to ESD damage.
Be careful about ESD!
You can use a transformer to isolate the chip inputs from the antenna.
See the pictures below and the schematics posted higher up in this thread.
This approach should work with all of them, see how it was done above with a generic straight from the factory, Newsky TV28Tv2 dongle which as far as this mod is concerned is electrically identical to the ones sold by rtlsdrblog, cosycave, etc.
(although I think the other midsized one works better in this context because it has better grounding for layout-related reasons, all four corners of the board being grounded, which is important to reducing HF noise. Also it uses the better crystal out of the box, and you don't have to pay extra for it.)
How you connect it can make a very big difference in the number of spurs you receive on lower frequencies.
You really need good bypassing, lots more bypass caps. The voltage regulation has to get major upgrades over what they come with for the dongles to work acceptably doing direct sampling at lower frequencies.