This converter has been carefully aligned and tested for proper gain, bandpass and noise figure. It has also been aged for several hours so that tubes, the crystal and other components which might fail prematurely have a chance to do so. It is very rare that a faulty component is reported. Nevertheless, as with all electronic equipment, some failures are bound to occur. All parts are in warranty for 6 months. If you feel certain a part has failed then you should write us describing the circumstances. If it is necessary that the converter be returned to us, we will repair it and return it to you at no charge. If you have localized a trouble to a tube, silicon diode or crystal, we will send you a replacement on receipt of the defective unit. Don't attempt to troubleshoot unless you're quite certain of your competence. CAUTION: Do not attempt to adjust or "peak" any of the slug-tuned coils or the piston trimmer at the input of the converter. You can only destroy the response curve and make the noise figure stay the same or get worse. The sensitivity of the converter to weak signals is NOT the best where the input or other circuits peak. IMAGE TRAP: In the middle compartment of the converter there is a coil and piston capacitor. This tuned circuit is set at the image frequency of the converter. Its purpose is to reject more fully any signal coming in at the image frequency of the converter. The image frequency of a converter is below the frequency to which the converter is tuned by twice the I.F. If you have a converter with a 14 Me. I.F., the oscillator injection is at 130 Me. and the image is at 144 minus 28 or 116 Me. If the interference from a station near the image frequency is at 146 Me. on your dial, the image would be at 146 minus 32 or 114 Me. If you have a local station operating near the image frequency of the converter, it is permissible to tune the trap a little in an attempt to null it out more completely. Don't change the setting much and remember about where it was set originally. It will rarely be beneficial to adjust the trap, so if you are not sure of yourself we suggest you leave it alone. I.F. CHANGE & REPAIRS: If you find that the I.F. frequency you have chosen is not suitable because of interference from strong TV, FM or commercial transmitters in your vicinity, notify us of this and we will suggest remedial measures, possibly the return of the converter for a different I.F. The return for exchange privilege applies only to a converter you have had in your possession for less than two weeks before notifying us of your problem. You can always expect a few unwanted birdies with a crystal-controlled converter, but they should not be a problem. In many cases of birdies, a cavity filter is the easiest solution . A very good one was described in the February, 1965 issue of VHFER magazine, published by our company.