Hr20 • 1 20 meter (14 mhz) all mode receiver kit ramsey electronics model no. Hr20 here’s the ideal mini-receiver for catching all the busy action on 20 meters from your office, home or on trips! Small in size but big in features: • easily tunes ssb, cw, rtty and am • smooth varactor tuning of any d...
Hr20 • 2 partial list of available kits ramsey transmitter kits • fm10a, fm25b stereo transmitters • am1, am25 am transmitters • tv6 television transmitter • fm100b professional fm stereo transmitter ramsey receiver kits • fr1 fm broadcast receiver • ar1 aircraft band receiver • sr2 shortwave rece...
Hr20 • 3 hr20 amateur receiver kit ramsey publication no. Mhr20 price $5.00 table of contents introduction to the hr20 .................4 about direct conversion .................5 circuit description ...........................6 parts list ..........................................7 schematic diagr...
Hr20 • 4 introduction: if you like plenty of action and dx (long distance) communications, the 20 meter ham band is the place to be. Almost 24 hours a day there’s something interesting happening on 20 meters. There are several groups of people who will enjoy this ramsey hr20 receiver: • experienced ...
Hr20 • 5 this receiver circuit is ideal for discovering just how simple a true “communications receiver” can be . That’s right- there is a big difference between the ramsey hr20 and other simple short wave radio circuits we can try to build. Yet it is very easy to build. Our hr-series are by far the...
Hr20 • 6 advantages of any direct conversion receiver include: • it is simple, and therefore economical and easy to build • it is quite sensitive even with a simple antenna • its tuning oscillator could even be set up to serve directly as a transmitter vfo in a simple transceiver setup. A common pro...
Hr20 • 7 parts supplied with the hr20 kit: capacitors: 1 15pf ceramic disc capacitor [marked 15 or 15k] (c4) 1 27pf ceramic disc capacitor [marked 27 or 27k] (c13) 2 36pf ceramic disc capacitor [marked 36 or 36k] (c1,c2) 4 .01µf disc capacitor [marked 103 or .01 or 10nf] (c3,c5,c6,c7) 2 4.7 to 10µf ...
Hr20 • 8 "learn-as-you-build" receiver assembly strategy: to help you learn just what exactly is going on we'll discuss the purpose of most of the components or groups of components as we go along. Since we are trying to keep assembly of the board simple, we will not be able to fully describe each i...
Hr20 • 9.
Hr20 • 10 hr20 parts layout diagram.
Hr20 • 11 receiver assembly: 1. Install the rca antenna jack, j1. Solder all four points. 2. Install c5, a .01µf ceramic disc signal coupling capacitor . This capacitor brings the signal up to the front of the pc board. Notice the long pc trace from j1 through c5 to r1. 3. Install potentiometer r1, ...
Hr20 • 12 are marked by polarity and must be installed in the proper direction. You’ll see that one side of the capacitor has a black band and is marked with a ‘-’ sign. This is the negative side, the other side is the positive lead. Make sure you insert the positive lead into the ‘+’ marked hole on...
Hr20 • 13 25. Install the 9-volt battery snap connector, making sure that the red (+) and black (-) leads are correctly installed. 26. Install c7, .01µf disc capacitor (marked 103 or .01 or 10nf). 27. Install c8, 4.7-10µf electrolytic capacitor. Observe polarity. 28. Install u2, the lm386 audio ampl...
Hr20 • 14 initial testing of your hr20: you’re now ready to power up and test your hr20, but before you begin take some time to sweep off your bench of any loose component leads or solder splashes. A clean work area not only makes testing less frustrating but also less prone to problems. Required fo...
Hr20 • 15 alignment: turn on whatever reference signal source you plan to use. This can be a regular transceiver keying a few milliwatts into a dummy load, a crystal oscillator or a signal generator. Or, you can look for a known signal that you have tuned in on another receiver. If you are without a...
Hr20 • 16 using your receiver: in your first tests, you might feel that tuning in cw and ssb stations by turning the control shaft seems tricky. Don't despair! The addition of a simple knob to the final version of your kit will result in more comfortable tuning right away. Also, the larger the knob,...
Hr20 • 17 sa602 audio output at the volume control, and switch in a pleasant oscillator pitch (keying sidetone) which is amplified to listening level by lm386. The ramsey electronics universal timer kit no. Ut-5 is easily adapted as a sidetone oscillator. • speaker operation a fifty cent, two inch d...
Hr20 • 18 • more audio power - another way if you want to use your hr20 for casual band monitoring while you are busy across the room, in the shop, to share with a class or club or group and want lots more volume, try building up our very inexpensive ramsey bn-9, 2 watt general purpose amplifier kit...
Hr20 • 19 troubleshooting tips: problem: all signals are chirpy and unstable. Solution: sorry to have to say it , but this condition is only caused by a weak battery! Use a fresh alkaline cell. Any strong signal forces the audio circuit to rob voltage from the oscillator, which cause the instability...
Hr20 • 20 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 ...
Hr20 • 21 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....
Hr20 • 22 frequency stability: a kilohertz of drift is not a big deal in fm circuits or a shortwave broadcast configuration, but any frequency instability is annoying when trying to receive cw or ssb. The varactor - controlled local oscillator is indeed a vfo, and therefore needs all the considerati...
Hr20 • 23 another way of getting bandspread for your favorite frequencies. Finally, it may be necessary to operate the counter on battery power only; connection of an ac adapter might introduce considerable hum into the receiver. The lm386 audio output: as already mentioned the lm386 is certainly ca...
Hr20 • 24 the ‘-’ side of the new capacitor is connected to the circuit trace leading to the volume control. Mount this capacitor as close to the body of the new lm386 as possible. Keep all leads as short as possible. This modification results in very good speaker volume but will also require closer...
Hr20 • 25 construction notes:.
Hr20 • 26 the ramsey kit warranty please read carefully before calling or writing in about your kit. Most problems can be solved without contacting the factory. Notice that this is not a "fine print" warranty. We want you to understand your rights and ours too! All ramsey kits will work if assembled...
Hr20 • 27 3. Factory repair of assembled kits: to qualify for ramsey electronics factory repair, kits must: 1. Not be assembled with acid core solder or flux. 2. Not be modified in any manner. 3. Be returned in fully-assembled form, not partially assembled. 4. Be accompanied by the proper repair fee...
Hr20 • 28 hr20 amateur receiver kit quick reference page guide introduction to the hr20 ................ 4 circuit description ........................... 6 parts list ......................................... 7 schematic diagram ........................ 9 parts layout .................................
