Bausätze ­ elektr. BauteileSiegfried PomplunLangemeerstr. 548356 Nordwalde

Tel. / Fax: 0 25 73 ­ 36 05E­mail: DL3BBX @ AOL.COM

"PRX80PR0"

"PRX80PR0"

DL3BBX

80­m­ARDF­PeilempfängerPRX80PRO Version 1.1

Neue Version

Februar 2000

Neue Version

Februar 2000

Foreword:

Based on the concept of the80-m-receiver PRX 80 from DF7XU, D.Schwider, the PRX 80 PRO wasdeveloped. The technical concept ofthis was retained, but the currentsinking logic has been fundamentallyover-worked. For this reason animprovement of the receiving capacityand a more effective manual controlwas reached. The improvement refer to4 essential points:

- HF-regulator- NF-filter- NF-power amplifier- layout of printed circuit board

Description of circuit:

The regulation of the integrated preamplifier and the IF-amplifier will bemade separately to get a betterlinearization of the standardcharacteristic, which is different fromthe concept before. Thereby theappraisal of the field strength is moreexactly possible and therewith thedistance to the receiver beacon bymeans of the position of theHF-regulator. The standard perimeter is85dB minimum. To improve the receivercapacity there was a optimized NF-filterbetween the outgoing of theZF-amplifier and the input of theNF-amplifier inserted.The NF-voltage for the power amplifiercan be adapted on the input of theLM386 over the two resistanceR28/R29; both resistance must reachtogether 50kOhm. The groundamplification of the LM386 can be moreelevated per fitting of the resistors R21from V = 20 ­ 200 trim. .

The transistor power amplifier with therelative small NF-amplification wascompensated to a modern IC-circuit(LM386). This IC gives a highNF-capacity with small distortions andoffers an excellent stability. In this way itis possible to obtain sufficient soundintensities in connection with insensitiveheadphones. To increase the stabilitythere were measures of coupling of byR16/C26 taken through. The layout isdeveloped totally new. With exceptionof C16 there are only used lessinductive capacitors in a2,54-mm-raster. Alternative for C16 a"styroflex" capacitor can be used,because ceramic capacitors with smallTK are not always available. Thecapacitors C16 and C17 areresponsible for the stability oftemperature of the oscillator andbecause of this they should be of typenp0 (ground color gray, black point).Parallel to C16 is also C28 provided.This one will not be fit and it is only forOM`s, who like to experiment, and whowant to make an exactly compensationof temperature. The trimmer C23 shouldbe a ceramic type with low TK. As a ruleonly capacitors with values to 12pFrequires these requirements. Ifnecessary you must fall back upon foiltrimmer, because these capacitors arenot always available. Foil trimmer havea bad temperature progress and theyare hygroscope. To get optimalreceiving properties, the oscillator andcircuit are parallel adjusted. Thetemperature coefficients for thecapacitors of the circuit (C1, C2, C4,C22) have no worth mentioninginfluence to the resonance frequency,because of the band width of some kHz.In opposition to other receiver concepts

Siegfried Pomplun ­ Langemeerstr. 5 ­ 48356 Nordwalde ­ Tel. (0 25 73) 36 05

80­m­Peilempfänger PRX 80 PRO de DL3BBX

the assistance antenna is out of a smallaluminum angle. The voltage there fromthe electric component of the EM-fieldwill be the direction determination perswitching on of the transistor amplifierT1 with the switch SW1 on the receiverinput coupled, by which the antennadiagram change into a cardioide. Thatmeans it arises an unequivocal directioneffect. According to the phase positionof the supplied voltage of the E-field thesignal will be louder or softer.

Assembly:

First of all you have to drive in thesoldering nails K5-K11. Subsequent thecomponent part, starting with thelowest, have to be equipped andsoldered in, in any successionaccording to the equipment plan. Do notforget the two bridges!

Test:

After assembling, check if allcomponent parts are on the designatedpositions soldered in with the rightvalues (optical control). Pay attention topolarity at diodes. Please check thesoldered positions, if they are orderlycomplexioned (optical control).

Assembly:

The assembly makes no problemsbecause of the extensive mechanicallypreparation and is to make accordinglyto the enclosed subscription. You mustshorten the potentiometer axlesaccording to the lengths of the deliveredbuttons. By no means clamp the cabinetof the potentiometers into the vise!Subsequent you have to assemblethese, and make the connection to thecircuitboard (K1-4, K12-18) with shortcords on the solder side of thecircuitboard according to the

subscription. After insertion of thecircuitboard into the cabinets, the ferritand the assistance antenna have toconnect into the accordingly solder pins(K5-K11). Therewith the receiver isready to operate. The PRX 80 PRO ison by plugging in the headphones.

Control:

Check all connections if the allocation isright (optical control).

Start:

Plug in the headphone into the for thatdesignated socket. In this way thereceiver is turned on. Now you can heara noise in the headphone.

Equalization:

adjustment before:P1 (frequency adjustment) = left touch(lowest frequency)P2 (HF-amplifying regulator) = righttouch (maximum amplifying)R21 = right touch (maximumamplifying).

With C23 you turn on the low frequencylimit to 3.490 kHz. The higher frequencyis then by 3.610 kHz. If you want thefrequency to reach 3.800 kHz, you haveto change the place where to switch thejumper. According to the ARDF-rules atransmitter sends between 3.500-3.600kHz, this means the receiver shouldonly be able to receive in this reach andthe tuning will also be more sensitive.The adjustment of the frequency limitcan happen with a suitable short-wavereceiver through interception of theoscillator frequency.

Tip: if you cannot reach the lowfrequency limit of 3.490 kHz, you haveto fit C28 with 10 pF!

The circuit (ferrit antenna) is to adjust tomaximum sound volume by C22 of3.580 kHz. To get this you have to use ameasuring transmitter, which is coupledloose or a faint station. You can limit themaximum amplifying of the receiver byadjust regulator R21. This regulator willbe adjusted on highest amplifying (righttouch). For the exactly adjustment the infront of me / back relation must turnedon R14. The correct equalization is onlypossible when the transmitter is about200 m away. So there is becoming acompromise between near- and farbearings. For equalization hold the PRX80 PRO so, that the operation elementsshow in direction to the transmitter. Turnon the receiving frequency exactlyaccording to the transmitting frequency.Turn on HF-regulator on middle sound-volume, then switch on key SW1 and re-gulate min. sound-volume with R14. Bythis action the aluminum angle must notbeen touched.

The receiver PRX 80 PRO is now inaction!

Partlist

CapacitiesC1 33 pF KerkoC2 680 pF KerkoC3 100 nF KerkoC4 680 pF KerkoC5 100 nF KerkoC6 100 nF KerkoC7 100 nF KerkoC8 100 nF KerkoC9 100 nF KerkoC10 1 uF TantalC11 1 uF TantalC12 1 uF TantalC13 100 nF KerkoC14 100 uF Elko, radialC15 270 pF StyroflexC16 39 pF Kerko, np0C17 100 nF KerkoC18 100 nF KerkoC19 100 nF Kerko

C20 100 nF KerkoC21 100 nF KerkoC22 22 pF Folientr. grC23 10 pF Folientr. yeC24 100 nF KerkoC25 100 uF Elko,radialC26 100 uF Elko, radialC27 10 uF Elko, radialC28 10 pF show textC29 4,7 nF KerkoC30 22 nF KerkoC31 10 nF KerkoC32 10 nF KerkoC33 3,9 nF KerkoC34 1 nF Kerko(C16 = Styroflex; down montage)

ResistorsR1 12 kOhmR2 220 kOhmR3 220 kOhmR4 12 kOhmR5 1,5 kOhm R6 220 kOhmR7 220 kOhmR8 82 OhmR9 3,3 kOhmR10 3,3 kOhmR11 33 kOhmR12 4,7 kOhmR13 4,7 kOhmR14 25 kOhm variableR15 10 OhmR16 10 OhmR17 3,6 kOhmR18 2,2 kOhmR19 4,7 kOhmR20 2,2 kOhmR21 5 kOhm variableR22 3,9 kOhmR23 47 kOhmR24 1 kOhmR25 560 kOhmR26 12 kOhmR27 47 kOhmR28 3,3 kOhmR29 47 kOhm

DiodenD1 BB109 B (black/yellow)D2 BB109 B (black/yellow)D3 1N4148 (red/black)D4 1N4148 (red/black)

Integrated CircuitIC1 TCA440 (A244D)IC2 78L05IC3 LM386

TransistorsT1 BF254 (BF199)T2 BC 547B

Other parts / componentsOSC1 OszillatorcoilP1 10 kOhm, PotentiometerP2 4,7 kOhm, PotentiometerSW1 Minibutton, workkontakt

1 Spezialcase 140x60x32 mm1 Ferritantenna, ready work1 3,5 mm one whole mounting, open1 Aluminiumangle1 rotary knobs 22 mm1 rotary knobs 18 mm2 hold­clip 15 mm2 protection­object 15 mm1 Batterieclip für 9­V­Akku4 distanz­roll 8 mm4 sheet metal­screw 3 x 16 mm1 Stiftleiste, 3­fach1 Jumper1 PZ16 precision­ic­socket1 Print PRX 80 PRO, V 1.0

Final information:

- if the destination fixing reacts wrong,you have to exchange the connectionsK9 and K10 (red).

- if the bearings shows deficientsensitivity as well as no reaction of thefront circle equalizer with C22 after ahard fall, so it is possible that the ferritbar is broken. With an inductivemeasuring instrument you can make outa broken ferrit bar very soon. Theinductivity of an intact ferrit bar is about23,4 uH.

If the potentiometer causes a scratchingnoise while tuning, a drop of oil (forexample Ballistol) can help.

How to handle the PRX 80 PRO?

The frequency regulator has to be tunedaccording to the frequency of thetransmitter. With the volume regulatoryou can find out a pleasant middlesound intensity. With a turn of 360degrees you will have two directions, inwhich the received­signal is very weak(low signal). These both minimas aremarked very strong and because of thisthey are clear to perceive. The bothminimas form a straight line of thelengthening of the ferrit antenna. Onthis lengthening you will find thetransmitter, which is beared of. Theminimum bearing is ambiguous,because of this you have to find outnow, on which side of the lengtheningthe transmitter is. For that you have toturn the receiver around 90 degrees(which means in right-angle) and pressthe small red­button on the left sight. Ifthe signal stays the same soundintensity or turns louder the transmitteris right in front of the searcher. If thesignal turns lower, the transmitter isbehind the searcher. While side fixingyou have to look on the front plate. Anddo not touch the aluminum angle. Nowthe searcher goes in the direction of the transmitter. Hereby he has to repeatthe above explained bearing actionsfrom time to time. As closer as thesearcher comes to the transmitter thelouder the sound in the headphones willbe. For perfect bearings you have toadjust the sound intensity(HF-regulator) with the sound intensityregulator. When the sound intensity istuned in correct you can hear thedifferences of the sound intensity veryclear.

Bestückungsplan zum

PRX 80 PRO

Bauteileübersicht über die wichtigsten der in der Schaltung verwendeten Bauteile undKennzeichnungshinweise.

Farbe 1. Zahl 2. Zahl Nullen Toleranzschwarz ­ 0 ­ braun 1 1 0 1 %rot 2 2 00 2 %orange 3 3 000 ­gelb 4 4 0000 ­grün 5 5 00000 0,5 %blau 6 6 000000 ­llila 7 7 ­grau 8 8 ­weiß 9 9 ­gold ­ ­ x 0,1 5 %silber ­ ­ x 0,01 10 %ohne ­ ­ ­ 20 %

Bei Dioden wird die Kathodedurch einen Strich oder Punktgekennzeichnet.

Keramische Kondensatoren ­ Kennzeichnung ­

Beschriftung Wert n27 270 pF 3n3 3,3 nF 1n0 1,0 nF 103 10 nF104 100 nF473 47 nF

Universal­NF­ Leistungsverstärker 0,3 bis 1 Watt, für niedrige Betriebsspannungen

Betrieb:

Der LM 386 ist ein Audio-Verstärker für universelle Anwendungen. Durch den Versorgungsspannungs­bereich (+4 V bis +12 V... Versionen N-1 bis N-3, M-1 und +5 V bis +18 V... Version N-4) und den gerin­gen Strombedarf (24 mA bei einer Versorgungsspannung von 6 V) eignet sich dieser Baustein beson­ders für Batteriebetrieb. Die Verstärkung ist intern auf 20 eingestellt, läßt sich aber durch die Serien­schaltung eines externen Kondensators und eines externen Widerstandes zwischen Anschluß 1 und 8auf Werte zwischen 20 und 200 einstellen. Sind die Anschlüße offen, so stellt sich die Verstärkung auf20 ein. Wird zwischen beide Anschlüsse nur ein Kondensator (z. B. 1O uF) geschaltet, so beträgt dieVerstärkung 200. Die Verstärkung läßt sich auch durch eine kapazitive Kopplung eines Widerstandes(oder FET`s) von Pin 1 nach Masse einstellen. Bei Verstärkungen über 20 sollte der unbenutzte Ein­gang überbrückt werden, wodurch mögliche Instabilitäten verhindert werden. Dies geschieht je nachWiderstand der Treiberschaltung mit einem 0,1 uF-Kondensator oder einer direkten Verbindung zu An­schluß 4. Der Frequenzbereich läßt sich beeinflussen, indem weitere externe Bauteile hinzufügt wer­den. Bei preiswerten Lautsprechern läßt sich der Bassbereich ausgleichen, indem man zwischen dieAnschlüsse 1 und 5 ein RC Glied einschaltet. Die Eingangsoffsetspannung läßt sich ausgleichen, in­dem man einen Widerstand vom unbenutzten Eingang auf Masse legt. Die Eingänge benutzen als Be­zugspegel die Masse, der Ausgang stellt sich automatisch auf die halbe Versorgungsspannung ein. Dieunten angeführten Daten beziehen sich auf den Betrieb dieses Bausteines mit einer Versorgungsspan­nung von +6V (Version LM 386 N 1).

Basis Emitter Collektor

BF 254BF 199

Eingang MasseAusgang

78L05

AM­Empfängerschaltung TCA 440

Verdrahtungsplan zum PRX 80 PRO

Perform the connections to the on this depending soldering connections

on the circuit board with cords which are as short as possible according to

the picture.

Now install subsequent the circuit board into the cabinet. At the end, connect the ferrit- and relief antenna to the appropriated soldering nails;connect the marked and the little bit longer wire ends (winding ends according to thewindings on the ferrit antenna) to the following soldering nails:

Red = K9 Yellow = K7 Green = K6

K14

K18 ­ Batterie

Urgent information (Date: April 2001)

Because of problems by transportation of the component parts there are sometimeschanges necessary. For that reason you always have to use the deliveredcomponent set and observe these information!

1) The operation voltage must be minimum 7,0 Volt, if not, the stabi cannot regulateanymore.

2) Very good for this is the Monacor headphone of type ES240.

3) The sockets of headphones are delivered from the producers in different types.The connection points in opposite of the sockets must maybe exchanged. Theground contact of the socket (shorter connection banner) is to connect with K18.

4) Should the lower frequency border of 3.490 kHz is not reached, so C28 must be fitwith a 10 pF-condensator (you find it enclosed to the component set).

5) Because of tolerances of component parts the tuning area cannot be exactly 120kHz (3.490-3.610 kHz). An exactly adaption can made with the resistance R1. Whenthe worth's are more than 12 k-Ohm the tuning window will be reduced.