Pr20—1 220 mhz low noise preamp kit • 16 db gain, 1 db noise figure • runs on 9 to 15 vdc • hi-q tuned input to reduce overload • small size to fit in any rig • the most popular preamp kit in the usa! • easy 15 minute assembly perk up your reception on 220 mhz with this easy-to-build and install kit...
Pr20—2 introduction to the pr20 low noise preamplifier a “preamplifier” gives an initial boost, measured in decibels, to the level of a signal before it is further processed by tuned circuits, filters, amplifiers, mixers, detectors, or other circuit stages. Preamps may be designed for either rf or a...
Pr20—3 circuit description l1 and c2 form a tuned input filter for the preamp to reject out-of-band signals. The 3 db bandwidth of this filter is 6mhz. L1 is adjustable for peak performance. The 2sc2498 transistor is a bipolar silicon npn low noise uhf/vhf amplifier in a to-92 case suitable for serv...
Pr20—4 parts supplied with pr20 kit capacitors 2 2 or 2.2pf disc capacitor (c1,2) 1 10pf disc capacitor (c3) 1 100pf disc capacitor [marked 100 or 101] (c4) 1 .01uf disc capacitor [may be marked .01, 103, or 10nf] (c5) resistors 1 470 ohm [yellow-violet-brown] (r1) 1 100k ohm [brown-black-yellow] (r...
Pr20—5 ramsey pr20 pre-amp parts layout note for pr-20: disregard c6 *.
Pr20—6 pr20 pre-amp assembly procedure soldering nine parts to a pc board is not a big job, but good performance of the pr20 requires attention to keeping all leads as short and neat as possible. The order of parts installation is not critical for this and other small kits, so the purpose of the fol...
Pr20—7 3. Install c4, 100pf (marked 100 or 101). 4. Install c5, .01uf (marked .01 or 103 or 10nf). Disc capacitor c5 is the bypass capacitor for the dc voltage supply points on the pc board. 5. Install q1, 2sc2498. Press q1 into its respective location on the pc board, which should be quite obvious ...
Pr20—8 two mechanical points after making sure that l1 is pressed firmly against the component side of the pc board. Progress summary: the wiring of your ramsey pr series preamp pc board is now complete. It will take you less than a minute to completely recheck every single soldering connection as w...
Pr20—9 testing and adjustment with your preamp installed between antenna and receiver, the only adjustment needed is the obvious one: peaking l1 for maximum signal strength. This may require more patience than most of us would think, because the adjustment should be made on a weak signal transmittin...
Pr20—10 pr20 on-off switching suggestion depending on your particular application and intended frequency, you may wish to use a dpdt power switch with one pole controlling voltage and the other pole connecting the input and output of the pr20 when the dc supply voltage is in the “off” position. This...
Pr20—11 a 220 mhz “active antenna” for situations where a simple indoor receiving antenna is needed, the pr20 preamp will add considerably improved performance to a whip antenna adjusted to 1/4 or 5/8 wave. And, for a very well engineered true active antenna for both hf and vhf at a break-through lo...
Pr20—12 2sc2498 characteristics: the 2sc2498 transistor is a bipolar silicon npn low noise uhf/vhf amplifier in a to-92 case, suitable for service up to 5ghz, with maximum device dissipation of 600 milliwatts. Other maximum ratings: collector -to-base voltage: 25 v collector-to-emitter voltage: 12 v...
Pr20—13 troubleshooting guide the only possible causes for malfunction of the pr20 are faulty or incorrectly installed parts. Re-check your work. Transistor replacement information is provided. Poor performance such as oscillation can be caused by bad parts-mounting (excessive lead length of resisto...
Pr20—14 the ramsey pr2: the ultimate broadband preamplifier after you find out how practical a well-built pr20 can be for 220mhz operating, you will be quite impressed with the “all bands” higher gain (also with very low noise) plus the convenient ac power supply, bnc i/o connectors and led on-off i...
Pr20—15 the ramsey kit warranty please read carefully before calling or writing in about your kit. Most problems can be solved without contacting the factory. All ramsey kits will work if assembled properly. The very fact that your kit includes this new manual is your assurance that a team of knowle...
Pr20—16 published by ramsey electronics, inc. Copyright 1994 all rights reserved. Ramsey electronics, inc. 590 fishers station drive victor, ny 14564 phone (585) 924-4560 fax (585) 924-4555 www.Ramseykits.Com call or write for our full line catalog! Partial list of available kits ramsey transmitter ...
