Ramsey Electronics HR40 manual General Notes For Experienced Qrp Builders, Alternate Power Sources

GENERAL NOTES FOR EXPERIENCED QRP BUILDERS:

We at Ramsey Electronics deliberately designed the HR-series of DC receivers to be easily available, affordable and buildable by any person willing to follow the assembly directions. To achieve this goal, the current models, with direct coupling of the SA602 to the LM386 operating with a gain figure of 50, use an amazing minimum of parts. If you know what you are doing with DC receiver design, we encourage you to use our HR-series for reliable building blocks for achieving maximum performance for you own application. If a good idea does not work as expected, you can easily restore your Ramsey receiver to its original circuit configuration.

Our job has been to keep in stock for immediate delivery a good basic design, a quality PC board with plenty of work room, useful front panel controls, correct and adjustable inductors, workable varactor tuning and the popular SA602. We know these receivers WORK, as specified, and that the ONLY reason any HR-receiver will not work after the 1-2 hours needed for assembly is if we packed the wrong parts or you put them in wrong. Once you are sure the receiver performs as specified, there is a lot you can do to coax maximum performance from the basic circuit.

For instance, if you choose a DC power source other than the 9-volt battery, the space allowed for the battery offers plenty of room for a top mounted perfboard or PC-board for preamp stages and or any sort of passive or active audio filter that suits your needs. Keep your work neat with short leads so as not to introduce broadcast station overload.

ALTERNATE POWER SOURCES:

Most of the HR40 circuitry can be operated from 6 to 14 volts without damage or significant modification. However, it is quite important that you carefully hook up with the correct polarity; reverse polarity or excessive voltages WILL damage your kit.

BANDSPREAD AND TUNING RANGE:

The easiest way to enjoy finer tuning , if you plan to use your receiver only for checking your favorite segment of the band, is to adjust the oscillator coil so that your desired segment falls within the second half of the rotation range of the tuning control. The first half of the rotation range covers about 70% of the actual tuning in KHz, while the other 30% is spread over the other half of the rotation range. If your interest is in monitoring SSB, the normal alignment will work fine. For optimum CW only listening, set the lower band edge with the tuning control in the 12:00 position of its range.

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