***************************************************************** * ARRL Radio Designer 1.0 File EXRF9503.TXT V 1.2 (21 Feb 1995) * * Exploring RF -- March 1995 *QST*, pp 76-78 * * compiled by David Newkirk, WJ1Z (dnewkirk@arrl.org) * * * * Modeling a Direct-Conversion Receiver's Audio Response * * and Gain with ARRL Radio Designer * * * * This file contains a complete ARRL Radio Designer netlist, * * and is most readable if viewed in a monopitch font like * * Courier. To use this netlist: * * * * 1) Copy everything from the beginning of this file down to * * and including the marker line * * * * *** end of EXRF9503.CKT *** * * * * to the Windows Clipboard. * * * * 2) Switch to Windows Notepad, press Ctrl+V to paste the * * Clipboard contents into Notepad, and save the Notepad file * * as EXRF9503.CKT in your ARRL Radio Designer subdirectory. * * * * This file also contains EXRF9503.CKT's corresponding report * * (.RP2) file in UUENCODEd, PKZIPped form, and you can recover * * the file if you have the utilities UUDECODE.EXE and * * PKZIP.EXE. See the portion of this file after the * * *** end of EXRF9503.CKT *** marker for information. (Don't * * fret if you can't recover the .RP2 file; just analyze * * EXRF9503.CKT and create your own reports using Linear * * Reports.) * ***************************************************************** * * This circuit file simulates the audio amplifier channel of a * "direct-conversion" 7-MHz Amateur Radio receiver. Dubbed the * "Ugly Weekender" Receiver" because of its "function, not beauty" * construction and its "buildable in a weekend" simplicity, the * UWR was published June 1992 *QST* by Roger Hayward, KA7EXM. * * In a direct-conversion receiver, a local oscillator * heterodynes the received signal directly to audio, as opposed * to a superheterodyne receiver, which first converts the * incoming signal to one or more *intermediate frequencies* * (IFs) for processing before the final RF-to-audio * conversion. The direct-conversion technique therefore requires * considerable audio gain -- "80 to 100 dB" (based purely on the * ratio of the receiver's audio output voltage to its RF input * voltage, irrespective of impedance) being the rule of * thumb. * * This block, MIXER, which corresponds to Figure 1A in *QST* * magazine's March 1995 Exploring RF column, simulates the * Ugly Weekender mixer's contribution to the total system gain * by modeling it as a 6-dB, 50-ohm attenuator. * BLK RES 1 0 R=150 RES 1 2 R=36 RES 2 0 R=150 MIXER:2POR 1 2 END * * This block, Q8-9-10, corresponds to Figure 1B in *QST* * magazine's March 1995 Exploring RF column. It simulates * the audio amplifier circuitry between the UWR's mixer and * GAIN control. * * The model uses ARRL Radio Designer's BIP element as simply as * possible, incorporating data for the only mandatory BIP * parameters: A (alpha, set at 0.99 based on an assumed beta of * 100 for all four of the UWR's 2N3904s) and RE (emitter * resistance, determined by coding each device's calculated * collector current into the Ebers-Moll-derived equation for * RE). * * (By the way, thank you for not howling [too much] at my * statement in the column that the 26 [or 25, as you may prefer * it] in the equation for emitter resistance [RE=26/Ic] means * "degrees Celsius, that is--room temperature." That equation * is really just a variation of the familiar resistance formula * R=E/I; in this case, the voltage [E] term, 26 [or 25 if you * prefer] is 26 *millivolts*, and actually comes from another * equation, V/T\=kT/q, where k is Boltzmann's constant [a * number that relates a molecule's energy to the absolute tem- * perature of its environment], T is the environment's absolute * temperature in Kelvins [293.16 at room temperature if * you assume that room temperature is 20 degrees C] and q * is the electric charge of an electron [1.6E-19 coulombs]. * The 26 is just the resistance equation's E (voltage), and so * the resistance equation's E is just the other equation's * V/T\--a voltage equivalent [V] to the thermally [T] dependent * energy of the transistor's semiconductor material. The fact * that 26 is close to room temperature in degrees C is * nothing but happenstance!) * * Such editorial slips aside, we can get away with such simple * transistor modeling in modeling the Ugly Weekender because * we're seeking only the system's gain, input impedance and * frequency response--all at audio frequencies. * * The collector currents coded into the netlist were determined * with NPNBIAS.EXE, one of 20+ utilties that ship with ARRL's * 1994 reprint of *Introduction to Radio-Frequency Design* * by Wes Hayward, W7ZOI. * * BLK CAP 10 0 C=0.1UF ; C30 CAP 10 11 C=10UF ; C27 BIP 13 12 11 A=0.99 RE=(26/0.636); Q8 RES 12 0 R=10KOH ; R30 CAP 13 0 C=10UF ; C28 RES 13 0 R=22KOH ; R33 RES 13 0 R=100KOH ; R32 CAP 12 0 C=0.1UF ; C31 BIP 12 14 15 A=0.99 RE=(26/0.5); Q9 RES 15 0 R=10KOH ; R36 CAP 15 0 C=10UF ; C32 RES 14 18 R=4.7KOH ; R35 RES 18 0 R=1KOH ; R34 CAP 18 0 C=10UF ; C33 CAP 14 0 C=0.1UF ; C34 BIP 14 18 16 A=0.99 RE=(26/0.886); Q10 RES 16 0 R=10KOH ; R37 CAP 16 17 C=10UF ; C38 Q8-9-10:2POR 10 17 END * * The next block, Q12, corresponds to Figure 1C in *QST* * magazine's March 1995 Exploring RF column. The Q12 * block models the Ugly Weekender's headphone amplifier, * which we assume drives a 2000+j0-ohm load, with * the circuit's 5-kilohm GAIN control set to maximum. * * Rather than include the 2-kilohm headphone load in the * netlist as a 2KOH RES element, we'll specify it in * Report Editor at report-generation time. * BLK RES 40 0 R=5KOH ; R38 (GAIN control set at max) CAP 40 41 C=10UF ; C39 RES 41 42 R=1KOH ; R39 RES 42 0 R=10KOH ; R40 RES 42 44 R=10KOH ; R41 CAP 44 0 C=0.1UF ; C40 RES 44 43 R=47KOH ; R42 BIP 42 43 0 A=0.99 RE=(26/1.919); Q12 RES 43 0 R=3.3KOH ; R43 CAP 43 45 C=10UF ; C41 CAP 45 0 C=0.01UF ; C42 Q12:2POR 40 45 END * * This block chains the MIXER, Q8-9-10 and Q12 blocks * to let us calculate the magnitude of the Ugly Weekender * Receiver's raw voltage gain (ARRL Radio Designer display * parameter MVG3). * BLK MIXER 10 20 Q8-9-10 20 30 Q12 30 40 SYSVGAIN:2POR 10 40 END FREQ ESTP 20HZ 20KHZ 500 END *** end of EXRF9503.CKT *** * The remainder of this file consists of a UUENCODEd version of a PKZIPped copy of the ARRL Radio Designer report file EXRF9502.RP2. You can recover the file if you have the utilities UUDECODE.EXE and PKUNZIP.EXE (they're commonly available from computer bulletin boards and via online services and the Internet) and you computer can run them regardless of which subdirectory you're logged into. To recover the file, take the following steps. 1) At the DOS prompt, and logged into the directory containing this EXRF9503.TXT file, issue the command UUDECODE EXRF9503.TXT. You now have two files: EXRF9503.TXT and 9503RP2.ZIP. 2) Also at the DOS prompt, and logged into the same directory as in Step 1, issue the command PKUNZIP 9503RP2.ZIP. You now have three files: EXRF9503.TXT, 9503RP2.ZIP and EXRF9503.RP2. Copy or move EXRF9503.RP2 into the subdirectory that contains EXRF9503.CKT, and you're ready to load its reports after analyzing EXRF9503.CKT. begin 666 9503rp2.zip M4$L#!!0``(`(`$!C,AZ^U]`;Y0(``,"5```,````15A21CDU,#,N4E`R[=U! M3Q-I&,#Q9R@M2.)M#WO9]4ET$D@HVFZB:,"D%%N(H$"S5/!4883BM%.&:="; M'\#$@_%J2(Q?PVB\<,#L<9.-VU,YDW3-YDY M_?/P@_3)N1=]8LGA7[]LV9NV;-J6#,EOZ[OB:R>F"[Y0J-1U>'!_1 MV6JM'NBJ[I:#3O)\T% MEW6I<3@V-A9^=6-7Q>PJFEK;9/9%)"X)B85G9Z;DR/N7UHQ:@S(8[NCQU\QU ML6;^V&L6BDOYS.R=5%S6S?6)\'?]WQH`W8N9.ZUQ;UKAZ^/!P:2(9IKG&L_: MZ&FKV:/G](,``````````````/`5N/:6;8*KJ+6Z:-FFMK0?-25;>0[U5*0?F4LUYKNOM MF@^+J2NFN3(EU6%OU2FW2J>/#+@RAXT!5Q8#KDYYP-75+O*IY2[6%$FN@#,Z MX"K>NF[_LP%7C7/[#+@"`````````````'P5]^T56U;:R=6/U@637$W(-9-< M/3?)U<>>_6>"RYX;E#857/25:>I5LOY7Y+1R*9V`""MY`;A M/*MP;Q(GB*NB#>V7E]:_`Z:_.TZHB;YG0-QC1T^':PBE@.]5WW_.LQIHAE09 MD;?