CRYSTAL SET CONSTRUCTION PROJECT COMPETION for AGM 2007

The NZVRS would like to hold a construction project competition for the best "Crystal Set" radio built by members, to be judged at the 2007 AGM. The Crystal Set design is open but the following criteria will be judged.

Design – 30% includes;	o	Circuit design and techniques of an earlier era 
o	General look and eye appeal (eg simplicity and elegance)
o	Authenticity and any innovation demonstrated.	
Execution - 30% includes;	o	Construction techniques employed 
o	Execution skills
o	Interesting components and materials 	
Performance – 30% includes;	o	Set performance (including sensitivity and selectivity).
o	Ease of operation	
Judges’ discretion – 10% 		

Design:  
i.	The set may be constructed of any materials, on a base less than 15 inches wide, 10 inches deep and a front panel of less than 8 inches high. All items of the set should be contained within these dimensions. 
ii.	The back and top shall be open so all wiring, connections and components can be easily inspected.
iii.	The set should have a maximum of three adjustable controls or switches for the judges to normally operate the set.  These controls should be on the front panel, be labeled and identified in the sketch of the circuit (see below) to indicate their affect on the operation of the set. Other adjustments not for judges’ use can be located inside the set.
iv.	Any tuning arrangement is permitted eg variable or switched capacitors, inductors, resistors etc. 
v.	The “Aerial and Earth” and “Phones” connection terminal points should be clearly marked.
vi.	No active devices nor bias or other (eg battery) power supplies are to be used at all – the crystal set is to be an entirely passive device. Variation of this point may lead to disqualification.
vii.	Any type of detector may be used but fixed is suggested as any variable detector (eg adjustable cats whisker) it will be replaced by a germanium diode by the judge(s) for ease of consistent results during testing. 
viii.	A simple sketch of the set’s circuit and identification of the controls is requested to assist the judges. Other than providing a basic understanding of the design of the set, the draftsmanship quality of the sketch will not be judged.

Performance will be measured by:
i.	Sensitivity to a standard low impedance signal source (coupled by 400 ohms in series with 300 pF to simulate a long wire aerial), connected to the aerial input terminal of the set under test. The test frequency will be about 1 MHz (1,000 kHz) audio modulated at about 800 Hz. 
ii.	A set level of the test signal will be then be varied above and below the initial test frequency, while monitoring the output, to determine the basic set selectivity.
iii.	A "standard" set of headphones (approximately 2,000 ohm dc resistance) will be used as the test termination. These will be provided by the judge and also be used to check the audio quality of the set.
iv.	The set should be capable of receiving signals from 550 to 1500 kHz.
v.	Additional points will be awarded to sets that are easy and simple to operate.

General:
i.	Only the set and circuit are required for judging. Additional accessories will not be judged.
ii.	The entries shall be completed and delivered to the 2007 AGM before noon. Absentee constructors are welcome to enter and reasonable care will be taken of submitted items, however the nomination of a proxy caretaker is suggested to look after the exhibit and to ensure its safe return. 
iii.	There shall be no maker’s identification marks on the sets other than a code number to be allocated by the secretary’s agent. This code shall be attached by a secure tie to a front or rear terminal and also written on the envelope containing the set’s circuit diagram (or the diagram itself). These codes shall be allocated and attached in a confidential manner so the judges have no indication of the makers. 
iv.	No member shall submit more than two entries.
v.	The entries will be judged by committee appointed judge(s) whose decision shall be final. The judges will strive to announce the results by the end of the AGM and these will be published in the next Bulletin. 
vi.	The prize(s) may include a certificate of merit for any category but the overall winner receives a free NZVRS subscription for the following year. 
vii.	See our website www.nzvrs.pl.net/crystal for possible additional background material.