The checkride PTS is pretty clear about radio knowledge/use.
Under the required task of RADIO COMMUNICATIONS those without a radio must be tested orally. In the PTS specifically for those aircraft without radeos:
NOTE: If the aircraft is not radio equipped, this TASK shall be tested orally for procedures ONLY. Exception: Single-seat applicants must be radio equipped.
So if you do not have a radio it odiously cannot be used during the checkride, however, you better be able to cover this orally.
OK, with a radio in the aircraft any applicant better be able to use it. This is one of the easiest ways to fail a checkride, to not be able to use a radio with the basic code for non towered airports:
Who you are calling
Who/what you are
Where you are
What your intentions are
Learn this. Practice in your car. Tattoo to your hand if needed.
If you have a radio and do not know how to use it you can fail the checkride 3 simple and easy ways:
First:
III. Airport Operations
A Radio Communications
1. Exhibits knowledge of the elements related to radio communications at airports without operating control towers.
2. Selects appropriate frequencies.
3. Transmits using recommended phraseology.
4. Acknowledges radio communications.
This is a cut and dry task. Know the code.
Second
B. TASK: TRAFFIC PATTERNS
1. Exhibits knowledge of the elements related to traffic patterns and shall include procedures at airports with CTAF, prevention of runway incursions, collision avoidance, wake turbulence avoidance, and wind shear.
2. Complies with proper local traffic pattern procedures.
3. Maintains proper spacing from other aircraft.
4. Corrects for wind drift to maintain the proper ground track.
5. Maintains orientation with the runway/landing area in use.
6. Maintains traffic pattern altitude, ±100 feet, and the appropriate airspeed, ±10 knots, if applicable.
To operate in traffic patterns, a radio is needed to accomplish this task.
Third
In the special emphasis areas there is "Collision avoidance" and "Runway incursion avoidance" as the third important area where radios are needed. Although a task is required to fail a checkride, reasons 1 and 2 above, the special emphasis areas.
Everyone out there without a radio or with a radio who does not know how to or does not use one is a danger to him/her self, any other pilots in the area, and those on the ground.
As you can tell, I feel that radios are very important to pass a checkride. If you want to know what is needed, I have the basics in my "Sport Pilot Checkride" book pages 123 and 124 with numerous examples that will help you ace your radio tasks for the checkride. The Sport Pilot Checkride book can be found at
www.ap-stores.com