EMRFD Chapter 6 Errata.   
  (25 Sept 16)

p6.6, right column 3.3 inches down from text top:   "A" becomes "An" instructive ....   (2Apr03)

p6.11, left col, 5.6 inches down from text top:  change "a" to "an" in ...produced an almost...   (2Apr03)

p6.11, left col, 3.3 inches down from text top:  change "with" to "without" .    (27July03)

p6.11, middle column, 2.0 inches down from text top:  replace "An NF of" with "A NF of"     (9Dec03)

p6.18, Fig 6.46.   The resistor between +12 and L1 should be 47 Ohms.      (3April10)    

 p6.28 Left col, bottom, one line up.    "it's own" becomes "its own".     (29Aug9)      (1 of 2)

p6.14.  Fig 6.37.  The figure was missing the reference designators used in the caption.  The updated figure is shown below.  (17Mar03)

   Fig 6.37
     (9 Dec 03)   Note:  The first version of this figure we had on the web was wrong. The "pull-up" resistor to +12 V should go to Q2 rather than to the anode of the diode.   The circuit in the 2nd printing of EMRFD is NOT correct.   It is still wrong in the 3rd printing.     The proper circuit is that shown above where R9 serves to put a positive bias on Q2 and a reverse bias on the diode in the no attenuation condition.   This resistor also biases the Q1 gate to a positive voltage to turn Q1 on.   When Q2 is turned on, it becomes an RF short circuit AND changes the DC conditions to cause Q1 to become an open circuit.   (17 April 09)

p6.37, left col, 1.1 inch down from top.   "it's" becomes "its".       (29Aug9)   

p6.20.  Fig. 6.49(C). The bottom most Vx  should be Vy.  (16Mar03) 

p6.20.   Fig. 6.50.  The text line in the lower left corner should use the phrase "designer/builder."   (31July09)   

p6.21.  Fig. 6.53(D). The line from the emitter marked "V-d"  should be marked "V-c" . (16Mar03) 

p6.21, left col, 0.9 inches down from text top.  Replace "RFCs" with "RFC"    (27July03)

p6.25, Fig. 6.57.   Mod the drawing by adding a reference designator, C2.  This is the 1uF/6 volt capacitor on the gate of Q9. (27July03)

p6.25, Fig 6.57.    The 1N4152 diode at the bottom of the drawing should have the direction reversed.    The cathode should attach to the 22K resistor.   (10Nov05)                                     

p6.26, col 3, two lines up from text bottom.  There is no "t" in Schwarz.  (27July03)

p6.29, left col, 2.3 inches up from text bottom:  change "ask"  to "asked"  (2Apr03)

p6.34, Fig 6.70, caption:     R10 should be 6.8 Ohms and not 6.8K-Ohms.  (26Dec06)      

p6.37, col 1, 3.1 inches down from text top.  replace "in need for some" with "in need of some"  (27July03)

p6.37, Fig 6.75.   Change a resistor from 3.6 to 6.8 Ohms.  

p6.40, Fig. 6.78.  The resistor at the base of Q3 is 22K.   Fig. shown below. (4june03)  

Fig. 6.78.

p6.44 , bottom of right text column:  replace "Fig. 6.84" with "Fig. 6.81A"    (2Apr03)  

p6.45, right column, 1 inch up from bottom of text:  Replace with "...102 dB and Receiver factor R=+5 dBm."  (4May03)

p6.47, right column, 2.3 inches down from text top:   The sentence beginning with "The lower reverse.." is technically confusing.  Replace this complete sentence with "The lower second stage reverse isolation generated an input impedance independent of output termination for the two stage design."     (2Apr03)  
p6.47, Fig 6.87.   Add label designating -6V, shown below    (10Aug03)

p6.48, col 3, 1.6 inches down from top.  Replace sentence "Symmetry is emphasized in the construction method shown in the photographs."  with  "Symmetry is emphasized in the construction."  (10Aug03)

p6.49, Fig 6.90.  The figure had problems with the numbering of the pins on the transformer, resulting in a phasing problem.   The proper information is shown in the new figure below.   Add the following sentence to the caption for the figure:   "Pay particular attention to the pin numbering for transformers T2 and T3."
old figure, not valid  This is the former figure.   
It all appears to be fixed in the 3rd printing.   (13 April 09)

p6.49, Fig 6.90.   This figure continued to have problems in both the first and second printing of the book.   Moreover, we didn't get it right in the errata of 17Sept03 shown above.   So Bill, W7AAZ, came to our rescue and pulled a board from the early version of his transceiver and traced the circuit.   The circuit below is the one that resides in a working transceiver.   Continue to pay particular attention to the pin numbering for transformers T2 and T3.  
Triad mixer in w7aaz xcvr,
This shows the configuration.   I have added some color to make sure that we differentiate this from the earlier drawings.   Red phasing dots have also been added to the drawing to emphasize the relationship, not only between the primary and secondary of transformers T2 and T3, but between the two halves of the secondary.

The following info is offered as a supplement to the text:
Consider a point in time when the LO signal has a positive voltage on pins 10 and 13 of the FST3125M.  This means that the two left switches in the mixer IC will be "closed" while the right ones are "open."    This is shown below.
positive lo phase
The right switches are open, so are not part of the circuit at this instant in time.   Moreover, we have eliminated the transformer halves connected to them, for no current flows in those windings at that point in time.  We can now use this diagram to trace the path between the RF transformer and the IF output and show that the phase relationship is additive for the two current components reaching the IF load.   A similar diagram for the negative LO phase can also be generated.    

This is not the only way that the transformers can be connected and produce a functioning circuit.   However, this is one from a working transceiver.   No matter what transformer connections might be used, the boundary conditions must be met.   (Many thanks to Bill for pulling a board to answer these questions.)    By now, many other analog switching integrated circuits have been used in this application by advanced experimenters.   The pin numbering may well be different with them.    The fundamental ideas remain the same.   The definitive reference is the work of PA3AKE at
http://www.xs4all.nl/~martein/pa3ake/hmode/index.html   (14March08)    

p6.50, Fig 6.93 caption.   Alter sentence to become "The variable capacitors with Y3 and Y4 are adjusted to match that filter to the one using Y1 and Y2."  (10Aug03)

p6.51, Fig 6.94.    There is an error in the input transformer in the schematic.   The original is partially shown here:
original ckt --wrong  This is the WRONG circuit.    Only the first FET is shown here, but there are four JFETs in parallel.  The original schematic shows the gate as being at the 5th turn on a 6 turn transformer.   In reality, the gate is across the full transformer while the input is applied to the tap.    The new, correct schematic is below:
corrected w7aaz amplifier
Corrected Fig 6.94.    The data in the text was obtained from the circuit shown above.   That is, the thing was properly built, but the schematic was in error.       (22March08)   (Still in error in 3rd printing, 13April09)    

p6.52, left column, 0.8 inch down from top:  replace "effort that anticipated" with "effort than anticipated."  (29Jan06)    

p6.53, left col, 0.5 inches down from text top:  "obtain" becomes "obtained"  (2Apr03)

p6.53, middle col in section 6.6, 0.9 inches up from bottom:   Replace "later" with "latter"  (2Apr03)

p6.53, 1st col, 1.7 inches down from text top.  Replace FMT3125 with FST3125.    (3Dec03)

p6.53, 3rd column, 3 inches down from top.  Replace "receives" with "receivers"     (3Dec03)

p6.54, left column, 0.5 inches up from text bottom:  "+17-dBm LO"  becomes "+17 dBm LO"  (2Apr03)  

p6.57, col 3, just above Transmitter IF Systems section.   The final sentence should become "A project elsewhere in the book (Fig 6.152) uses this topology with a diode ring balanced modulator."  (10Aug03)    

p6.60, Fig  6.107.    We got into trouble because we pulled this figure in from an earlier QST article.   The labels on the input and output don't make sense.   So at the input, cross out the two lines, leaving only the "-10 dBm" part.   At the output end, cross out the reference to "C, Fig 5" and add "output."      (29Jan06)       

p6.62.  Fig. 6.112 is missing some parts.  Here's the proper figure:  

Fig 6.112.  (24Feb03) 

p6.63, Fig. 6.113.    Eliminate the "+8V" that is next to the BFO Input label.  (2Apr03)

p6.64, col 1, 1.0 inch down from text top.   Make sentence become "...in U4 to adjust balance." (10Aug03)

p6.66, Fig 6.118.   Change the 10K resistor  between R1, the "TX Trim" control and the inverting (-) input of the op-amp to a 5K.  (Actually, a 4.7 K would work fine.)    This will then allow the circuit to be set up to achieve the voltage levels quoted.   With R1 set to generate 0.75 volt, V-cont will be 7.5 volts during TX or "RIT off."   With RIT on, V-cont should vary from 5.5 to 10.5 volts. (3Aug07)

NEW in 2016  p6.66, Fig 6.118.    A reader reported difficulty in getting this circuit to function.    An experiment showed that the 2N7000 was not switching properly.   The diode intrinsic to the MOSFET was getting in the way when there was a moderate voltage across the FET.    This caused the voltage at pin 1 of the op-amp to change when in T as the RIT pot was changed.     Hence, we did a redesign of the circuit.   The suggested circuit is presented here:
  Some resistors (R1, 2, 3) are marked as 2%.   These are metal film resistors that establish the output voltages.   Many other 10K resistors appear in the circuit, but are not as critical, so junk box things are allowed.   Resistor R5, shown as a 5.1K, is switched in during Transmit, or when RIT is off.   This fixed R is not critical.   It merely places a load on the 5 volt supply that is the same as R4, the RIT pot.   If you use a different R4 value, pick R5 to be about the same.    This then keeps the load on the 5 volt supply approximately constant.      Note that R4 sits on the 5 volt supply with the ground end switched.     (25sept2016)

p6.67.  left column, 1.5 inches down from top:   replace  "...stopped tuning and listen to" with "...stopped tuning and listened to"  

p6.67,  right column, up 1.8 inches from bottom:   replace "..is less then" with "..is less than".    (29Jan06)    

p6.68, right column, 0.4 inch up from bottom:  replace "...line go low" with "...line goes low".    (29Jan06)

p6.68, Fig 6.122B.  The diode as shown in part B of the figure does nothing to protect transistor Q1.   Move diode D1 so it is between the collector of Q1 and the +12 volt power supply rail as shown.   Now, when a "T" period ends and Q1 stops conducting, the current flowing in the relay will continue to flow for a while in the diode and will not cause a voltage spike that might break Q1.   The new figure is shown here:


p6.70, right column, 1.2 inches down from text top.  Remove the ) from the end of the text. (26Mar03)

p6.71, col 1, 3rd line down from top of text.   "600-V" becomes "1000-V"  (10Aug03)

p6.74 and 6.75, Fig 6.132.   There are several reference designators missing in this schematic that are referenced from the text.   Having them in the schematic diagram facilitates the text descriptions.  Add the following designators:
    J1    The Mic input, upper left corner of diagram.
    R1    The 20K pot at the Mic input.
    J2    The receiver input  labeled RX In, 2.4 inches down from top border of figure, and on left side.
    J4    Connector attached to capacitor that then attaches to collector of Q2.
    D2    Attached to col of Q2.
    D3    Attached to col of Q3.
    J5    Connector attached to capacitor that then attaches to collector of Q3.
    J16    The connector coming from "CO1" which is above Q15.
    J17    The connector coming from "CO2" which is above Q15.
    J19    The connector coming from "LO1" which is above Q14.
    J20    The connector coming from "LO2" which is above Q14.
    (Now we move to the right hand part of the figure, p6.75)
    C36    Shunt to ground capacitor attached to L4, the inductor coming from the 6 dB pad, upper left of page.
    R58    20K pot attached to source of Q10, 4.0 inch up from bottom border and 5.6 inches left of right border.
    R14    20K pot on collector of Q1, 2.3 inches up from bottom border and 4.6 inches in from right border.
    J13    Connector from CO2, 2.5 inches up from bottom and 2.7 inches over from right edge of figure.
    J14    Connector from LO2,  2.5 inches up from bottom and 1 inch over from right edge of figure.
    D6    Diode attached to collector of Q11, bottom right corner of figure.
    D7    Diode attached to collector of Q12, bottom right corner of figure.   (10Aug03)

p6.76, col 3, 2.2 inches down from text top.  Change "D1 and D2" to "D2 and D3"  (10August03)  

p6.78, Fig 6.136.    Add the following line to the caption for this figure:   "L401 and 402 are labeled as RF chokes, for the network is formed with molded RF chokes."      (29Jan06)             

p6.81, Fig 6.142 and related discussion:   See errata for page 7.43 for this date    (16Aug06)  

p6.83, Section Title.   This should be section number 6.10 . (7Mar03)

p6.84, Fig 6.148.  The MV209 Varactor diode should be labeled D900.    (29Jan06)

p6.85, Fig 6.150.   The two output labels should be changed from "+6 dBm" to "+6 to +8 dBm"  (29Jan06)  

p6.86, Fig 6.151.   Change the caption.   Final sentence should become  "The amplifier input resistors, now 6.8K, can be changed to set the output power."   (7Mar03)

p6.86, photo on bottom left.   Replace the caption with "The RF power chain up through Q3.  See Fig 6.154."  (3Dec03)  

p6.86, Fig 6.151 Caption.    Change the sentence to read "T301 and T300 each have a 20-turn primary with a 5-turn secondary on  FT-37-43 cores.     (12Jan07)

p6.86, right column, 1 inch down from top:   replace "filter is build" with "filter is built"     (29Jan06)    

p6.87, Fig. 6.152.  There are missing reference designators on the drawing.   Also, change the caption to read "Fig 6.152--SSB Generator. R615 and R624 should be ...."   The updated figure is shown below: (15Mar03)
Fig  6.152.

p6.87, Fig 6.152.  The figure contains a mixer in the lower right corner.   Directly above that mixer is a network of three resistors leading to a coax connector.   The 10 Ohm resistor should be changed to 18 Ohms to make it be a 3 dB pad.    (8Nov10)

p6.88, Fig 6.154.     The output low pass filter around L3, 4, and 5 contains four capacitors.    The output capacitor, shown as a 133 pF, should be a 75 pF capacitor.      (1Mar06)         .

p6.90, Section Title.   This should be section number 6.11 .. (7Mar03)

p6.90, Fig. 6.157.  Add reference designator for Q403.    (10Aug03)

p6.91.  Fig. 6.158.   L1-L4 are 360 nH, 10 turns #26 on a T30-6. (4Mar03)