EMRFD Message Archive 15388

Message Date From Subject
15388 2019-08-30 00:08:40 Ken Chase Supply decoupling resistor
Hi All

I've been reading EMRFD and I've come across several circuits that have low value resistors between the supply and transistor collectors.

Sample circuits are Page 1.18 Figures 1.33 and 1.34 of EMRFD.

What is the purpose of these 100 and 10 ohm resistors between the supply and collectors?


15389 2019-08-30 09:32:45 Rob Re: Supply decoupling resistor

15390 2019-08-30 09:41:08 w7zoi Re: Supply decoupling resistor
Hi all,
I'm out traveling to a memorial service, but will address this next week.   Decoupling is a big deal.   Look at the subject in Ch 2.   
73, Wes, w7zoi

15391 2019-08-30 09:41:20 Dana Myers Re: Supply decoupling resistor
15392 2019-08-30 11:41:04 Ken Chase Re: Supply decoupling resistor
Thanks Dana And Wes

So how is it determined the size of the resistors?

My first thought when I saw this is if the transistor shorted the supply would go to ground. The resistor would be between the + line and ground.



15393 2019-08-30 11:41:29 Jim Strohm Re: Supply decoupling resistor
Decoupling resistors  -- I haven't yet reviewed the referenced section of EMRFD, but I've seen these used in what amounts to a pi-network low-pass filter to knock down spurious signals or to filter out power supply crud.  Instead of an inductor as in the low-pass pi-network filters you're used to, a resistor is used. 

Without simulating the circuits in question and playing with values, I can't offer much more guidance.  However, if the circuit designer put in a "decoupling" resistor (whatever that ACTUALLY means), I'd suggest trying it first before removing or changing it.   We're talking about a 5-cent resistor here ... or free if your junk box has an old transistor radio in it. 

Have you tried putting a variable resistor in place of your "decoupling" resistor to see what effect it has? 


15394 2019-08-31 23:37:35 kerrypwr Re: Supply decoupling resistor
I don't think that the resistor is explained in EMRFD; I haven't found such an explanation.

There is, however, so much information in EMRFD that it's sometimes difficult to know what's there and not there.

The resistor is very well explained in Wes' IRFD on page 13; in this description R4 is the resistor in question and C3 is the capacitor to ground from the "transistor" end of R4;

"C3 is also part of a decoupling network with R4 being the remaining part.  This RC network serves to prevent any stray signals that may be superimposed upon the power supply from reaching the amplifier.  The filter should have a cutoff frequency that is low compared with the frequency of any noise that may be anticipated".

The description also mentions a capacitor sometimes used to ground the "Vcc" end of the decoupling resistor and recommends that no capacitor be used in this location for fear of coupling ground currents between other stages if such exist.

Kerry VK2TIL.
15395 2019-09-01 08:15:52 Donald philbin Re: Supply decoupling resistor
I suspect it is used in conjunction with the filter capacitor(s) to construct a filter... (high pass??) with the proper RC time constant .

I should stick to chemistry :)

15396 2019-09-01 08:17:24 Rob Re: Supply decoupling resistor

What is IRFG ?

15397 2019-09-01 08:41:33 Vern VanZ Re: Supply decoupling resistor
IRFD - "Introduction to Radio Frequency Design".  Acronym for the title of a very good book by Wes Hayward.  I don't know if it's still available (new) from the ARRL, Amazon, etc., but there may be used copies around from other sources if not.


Vern - N7GTB

15398 2019-09-01 09:12:08 Mike Nothdurft (K... Re: Supply decoupling resistor

I believe PDF copies of both IRFD and Solid State Design for the Radio Amateur are included with purchase of the latest version of EMRFD from ARRL.





15399 2019-09-01 09:37:52 Dave Daniel Re: Supply decoupling resistor
I just checked and indeed uying a copy of EMRFD from the ARRL includes a CD with PDF copies of those two earlier books. This is great news for those who are thinking of buying a copy of EMRFD.


Sent from a small flat thingy

15400 2019-09-01 14:01:10 kc8sbv@gmail.com Re: Supply decoupling resistor
Todd VE7BPO  has great analysis of decoupling here with his LM386 analysis...

About halfway down the page...

15401 2019-09-01 14:05:01 Rob Re: Supply decoupling resistor


now I know to look for.....

a CD with PDFs.....................

which is not in the pouch in the back of my EMRFD book.


15402 2019-09-01 14:18:14 kerrypwr Re: Supply decoupling resistor
IRFD & SSD are only on the latest CD (2017, I think) that accompanies EMRFD; earlier editions such as most of us probably have do not have that great bonus.

My IRFD is in paper form.

Kerry VK2TIL.
15403 2019-09-01 14:28:00 Dave Daniel Re: Supply decoupling resistor

Well, the CD that came with my copy of EMRFD, which I purchased a while ago does not have those PDFs on it. I just checked my CD to be sure. But the description of the current copy of EMRFD (which is pretty much the same as the one published many years ago) on the ARRL website store reads that the included CD has those PDFs. I don't know when the CD first contained those PDFs, but you'd have to find one of those and not an earlier CD such as mine.


15404 2019-09-03 11:52:37 Rob Re: Supply decoupling resistor
I found the PDF.

Thank you.

15405 2019-09-03 18:52:42 Zach Metzinger Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
15406 2019-09-03 21:39:23 Mike Nothdurft (K... Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

Well here’s the story.  A few years back ARRL decided to no longer publish EMRFD (which at that time included a CD with several software programs and a bunch of articles from QST and other sources.)  However, there arose a huge “Hue and Cry”

Hue and cry definition, the pursuit of a felon or an offender (The ARRL) with loud outcries or clamor (by the amateur community) to give an alarm regarding a crime (discontinuing the publishing of EMRFD). ;-)

After the fury settled down the ARRL got with Wes Hayward and it was decided to again publish EMRFD.  At this point much of the software was pretty long in the tooth and possibly wouldn’t run on today’s computers so they decided instead to include the PDFs of IRFD and SSDRA.  Although these works formed the basis for much of EMRFD there is a lot of more in depth information on some subjects in these books.

Wes, please correct any inaccuracies in this comment.





15407 2019-09-04 00:11:12 Dave Daniel Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]


I am confused by your email; the current copy of EMRFD, when purchased from the ARRL, *does* contain a CD that has PDFs of SSDRA and IRFD. Since I have bound copies of all three books, it would not make any sense for me to purchase another copy of EMRFD from the ARRL just to get those PDFs,

It took me many years to find my copy of SSDRA; I used ABEBooks' "watch list" facility and checked bookfinder.com often to maintain the search over the years until I found a copy.

It is quite possible that your email to the ARRL (and perhaps others) is what prompted the ARRL to include these books in PDF form with EMRFD; obviously, Wes would have had to be in that loop somewhere.


15408 2019-09-04 08:58:27 Zach Metzinger Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
15409 2019-09-04 11:01:01 Rob Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

Just curious.....

I thought EMRFD was a culmination of IRFD and SSDRA efforts.............

why the sudden interest in SSDRA?

Is any one of these 3 books written for very novice hobby radio builders?

15410 2019-09-04 11:05:09 Dave Daniel Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

Yes, I agree with your sentiment. If I found copies of the books in question in PDF for online, I'd want Wes and Rick to get royalties. Unfortunately, that isn't always the case. In the case for the IRFD and SSDRA copies that come with the current copy of EMRFD on the ARRL website, I assume that they get royalties.

Mike's earlier email describing how that came about was interesting to me.


15411 2019-09-04 11:08:57 Dave Daniel Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

And Doug DeMaw.

15412 2019-09-04 11:18:08 John Lawson Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
You can find SSD on Amazon for a reasonable price at the low end of the pricing...John

Sent from my iPad
15413 2019-09-04 14:39:14 Zach Metzinger Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
All of these books have good information in them. In my opinion, SSDRA presents a more information-dense picture of practical knowledge for anyone developing HF gear. EMRFD tends to gloss over some details and push into the corners of phasing design and somewhat dated DSP. Note that even EMRFD says, in the Preface, that it is "the sequel to SSD".

The two "W1FB's ..." books present a different approach to some of this information. There will probably never be a one-to-end-all book for homebrewing, and sometimes one author can convey a topic in a way that resonates with the reader where another author did not.

--- Zach

15414 2019-09-04 14:46:10 Zach Metzinger Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

15415 2019-09-04 15:29:57 Mike Nothdurft (K... Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

Although I didn’t give them credit in my previous post I think the other authors of EMRFD (Rick Campbell and Bob Larkin) also  contributed to the reinstated publication of EMRFD.



15416 2019-09-04 15:59:05 Zach Metzinger Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

Noticed that you are in the DFW area, as am I. Are you aware of any homebrewer meetups around this area? It would be interesting to get people together offline and show/discuss projects.

(Please excuse this post if the group is not the right place for this. Others in the area might be interested, so I didn't do a private email.)

--- Zach

15417 2019-09-04 16:46:55 Dana Myers Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
15419 2019-09-04 18:14:03 Zach Metzinger Re: CDROM w/ PDFs
15421 2019-09-04 18:57:06 jim Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]
The preface of my copy of IRFD sez (in reference to who it was written for) " The third group is the electronics hobbiest including the radio amateur. While there are many serious experimenters with in an interest in the subject matter, this volume will probably be limited to those "hams" with a moderate formal background" ...copyright 1982 (prentice-hall)


15422 2019-09-04 18:59:17 Ashhar Farhan Re: CDROM w/ PDFs
These books span the builders. I was a very green builder, having built just one receiver until I read the EMRFD. What got me started was the S7C receiver. It came through wonderfully. Then I added a modulator to it and viola! I had an SSB exciter too!
The real breakthrough of emrfd is it encourages you to build, measure and then build more in steps. The first chapter is available for free download. Read it to understand how the book is written.

73, f

15423 2019-09-04 19:50:04 Vern VanZ Re: CDROM w/ PDFs
Zach and others,

I have no idea which book, page, etc., "Fig 1.9" refers to, but as a long time lurker here, reader and builder of circuits from the afore mentioned books; I agree with what Zach said, and proposed.  So with that said, count me in.  I'm nowhere near as steady of hand, nor see as clearly as I did when the Solid State Design book was available. But i still build/smoke circuits, (find the problem) and build again.

My suggestion is, get and keep a notebook and chronicle your experience, measurement(s), and findings. When things fail (and they will), document it in the notebook. Do the work, look for answers, and when none can be found, ask questions of others here...  Don't fear what might go wrong. :)

I have fifty projects going at once, but ( between fishing trips ) will gladly do what I can to help the effort!

Vern - N7GTB
15424 2019-09-04 20:27:06 Zach Metzinger Re: CDROM w/ PDFs

Ah, sorry. EMRFD page 1.8 is where figure 1.9 resides.

--- Zach

15425 2019-09-04 20:56:04 w7zoi Re: Supply decoupling resistor
Hi Ken, and gang,

OK, got home, but brought a cold with it.   Still sneezing, but better.   Avoiding lawn work, which gave me time to simulate and write.     So I got a piece done on this decoupling and bypassing issue.   Just got it up on my web page.   It's at
http://w7zoi.net/bypass/decouple.html     I hope that this helps.   It's an important thing to use during a design.

Now for some other stuff that has come up:    Emrfd came out in 2003, which now seem like so long long ago.   In some way, it was just the other day.   Anyway, we went through three printings.   The third printing was called the "Revised First Edition," for we updated some things and got some of the house keeping cleaned up.    Alas, the printer screw up the first chapter.    Rather than reprinting things, the League just put the first chapter on their web site.   That had the virtue that folks could read the first chapter before they buy the book.  But this finally came to an end a couple of years ago.     We let it go as the end.   

But then I get a letter from Steve Ford at the League and he tells me that they want to put out the 3rd printing as a "Classic Reprint Edition."   This merely means that nothing is changed from the final printing, but it is available still, at least until they run out.    The CD has the many articles that we always had, but does not have the software.   That was because a virus detection program didn't like it and thought that it "might" have a virus in it. So the League pulled it.   The software still works fine for me, but not for the other folks who are afraid of it.   I get it and didn't fight it.   I have friend in the business and he has had the same problem.   

I had digital copies of SSD and IRFD and suggested to Ford that we include them.   He thought that would be a cool thing and they went for it.   

As far as I know, there are no legal digital copies of SSD, IRFD, or EMRFD out on the internet.   

73, Wes

15426 2019-09-04 22:17:03 Vern VanZ Re: CDROM w/ PDFs
Ok, I'm on the same page now.  Chapter 1 of EMRFD, page 1.8, Figure 1.9; a schematic showing a direct conversion receiver (40 meters) using a NE602 as a oscillator/mixer, and an LM386 audio amp.  I should have all these parts in the junk box, but mine has been a couple of decades (at least) getting stocked...  I see that on the next page (1.9, Fig 1.11) the circuit has been built on a copper clad board, and housed in a nice die cast aluminum box.  But to start (and test) everything could be built on the board and tested, before being mounted in the box...

The circuit is now more than 20 years old...so how available are these parts today?  A quick google shows a number of online sources for the NE602, and the LM386 is available from Mouser (didn't check DigiKey, etc), so those needing and willing to purchase parts should be ok.  If not, similar designs exist using discrete transistors and diode ring mixers. Not the same performance as the Gilbert cell, but the LM386 (or similar) could still be used.  The variable caps/trimmers might be a different story... I see them on Ebay, some from the former USSR.  They may not be the same value/range, but with some adjustment of surrounding component values, I would think they should still be usable. 

Either way, just some thoughts, for whatever they may be worth. :)

I'm available to help build and show off...just hoping more here will join in.  The result if nothing else, would be another fun piece of gear for that camping/fishing/field day trip.

Vern - N7GTB

15427 2019-09-04 22:48:49 Dana Myers Re: CDROM w/ PDFs
15428 2019-09-04 22:50:00 Zach Metzinger Re: Supply decoupling resistor

> I had digital copies of SSD and IRFD and suggested to Ford that we include them.   He thought that would be a cool thing and they went for it. 


I completely understand. If you still have the ARRL's ear, and you feel that it would be a good thing, there are those of us who got the edition with the programs on CDROM. We'd also like to get a CDROM of SSD/IRFD, and would be more than happy to pay for it, but we don't need a second copy of EMRFD.

The ARRL just has to make that an option.

--- Zach

15429 2019-09-05 09:31:36 David Wilcox Re: Supply decoupling resistor
For those asking about applicability of these books for noobies, my thoughts are that after 50+ years as a ham (it is my avocation, not my vocation) I still consider myself a nooby.  All three of the aforementioned books answer most of my questions when I am looking over a schematic and asking “why did they do that” or “what do those parts do”.  I may have to read it three or four times at my age but they are still great reads and very applicable to my hobby.  It is still a hobby that is cheaper than a psychiatrist and less trouble than a mistress.  I am currently re reading “The Impoverished Radio Experimenter” series.  For those who are too young to remember tubes (Valves in other countries) it gives very basic information on how tubes work and full instructions for building a few tube radios from the 1920’s.  Yes, the parts are still available, cheaply I might add. I have forgotten so much.  Much of it is translatable to transistors and then that gets you into EMRFD, etc.  I still treasure all of Doug Demaw’s books and they hold a prominent place on my radio book shelf.  All noobies should get a set of those too.


Dave K8WPE since 1960

David J. Wilcox K8WPE’s iPad

15430 2019-09-05 09:31:57 Rob Re: CDROM w/ PDFs

I learned more about making radios from scratch doing the NE602 LM386 direct conversion receiver than ANY other radio project I ever played with.

My goal was to learn how to make a 7.030 mHz CW receiver that would cut out

ALL possibility of hearing any broadcast radio stations spew political or religious or sports swill.

Which really was the only thing I ever heard building simple crystal radios.

Which is a real bitch when you try to share the hobby of ham radio and parents declare this is not appropriate for their children. 



15431 2019-09-05 09:35:23 Rob Re: CDROM w/ PDFs NE602 DIP are NOT rare

EBAY has dozens of sellers of NE602 BUY IT NOW ... not auctions

that sell the NE602  and SA612  .....    DIP   NOT   surface mount crumbs.......

for about $1.50


I bought them from 5 different EBAY sellers and ALL of them worked in my circuits

and then

I bought them from www.aliexpress.com and they were defective

and useless to get a refund so I NEVER use aliexpress again.....

and only buy from EBAY if I can't find a component at MOUSER or DIGIKEY at acceptable pricing.

I also use BANGGOOD.com for components.

15432 2019-09-05 09:58:50 Zach Metzinger Re: CDROM w/ PDFs NE602 DIP are NOT rare

kitsandparts.com and Dan's Small parts are also good sources, with the former having great prices on powered iron toroids.

Pedal parts plus and small bear electronics both have BF244 JFETs (good sub for 2N4416) in TO-92.

Futurlec has obscure transistors.

--- Zach

15437 2019-09-05 14:01:55 Rob Re: CDROM w/ PDFs EMRFD SSDRA IRFD TEOR .... JAA ... just another ac


....  JAA ...   just another acronym

adding THE ELECTRONICS OF RADIO by Rutledge to the list of hands on HOW TO books in my library.....

that I chased down to learn how radios actually tick......

I have to admit that I am NOT qualified to do most of the algebra involved


once they get too deep in the math I'm lost


THE ELECTRONICS OF RADIO assumes you have an instructor and test equipment on the bench

while you step through that book.

Which really sucked for me because when I asked questions on forums I got a lot of "go read the manual" answers.

I would like to be able to recommend one of these for newbies when guys in the local radio club...or their kids...

show up on our doorstep and ask where to start.

Telling them to go subscribe to the ARRL and get this year's handbook is not a correct answer to that question ...anymore.

I went full circle this past year......

20 years ago I built a PIXIE called a KNIGTHSMITE

and this past year I built a PIXIE

and printed circuit boards:


>Just curious.....

> I thought EMRFD was a culmination of IRFD and SSDRA
> why the sudden interest in SSDRA?
> Is any one of these 3 books written for very novice hobby
radio builders?

It depends on what you mean by "very novice". I'd be inclined to say
none of these are for true novices - something like the W1FB QRP
Notebook or somesuch might be more appropriate there - but SSDRA
and EMRFD are pretty-well tuned to helping a reasonably experienced
electronic enthusiast get started with RF experimenting. IRFD is
not for novices.

Dana  K6JQ

15438 2019-09-05 19:05:50 Ken Chase Re: Supply decoupling resistor
Hi Wes

Thank you so much for your decoupling web page.

I've been away as well and haven't looked any further into the decoupling  research. This will help a lot.

My question regarding the decoupling resistor rose from watching Charlie Morris videos. I had asked him the purpose of the 100/10 ohm resistors and he said it was his attempt on killing noise back into the supply. That's what brought me here.


15440 2019-09-06 14:45:09 Mike Nothdurft (K... Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]


I’m not aware of any homebrew meetings but since I’m not a member of any of the local amateur radio  clubs I can’t say that there aren’t any.  I think some sort of homebrew “Show and Tell” event at the next HAMCOM would be a good idea .  I may suggest that if I can figure out who to contact.  If there are other parties in the DFW area interested in some sort of get together please chime in.




15442 2019-09-07 20:58:56 Dave Hartman Re: Supply decoupling resistor
Just curious... did the errata get folded into the book?
And a lot of that software is a bit long in the tooth. Surely there must be more modern equivalent or better SW out there, or online calculators.  Excuse me while I go and lubricate my slide rule...
--  Dave - AC2GL All typing errors are my own work and subject to copyright laws, except errors by the spell checker which are open source errors.
15443 2019-09-07 21:33:41 Ashhar Farhan Re: Supply decoupling resistor

The software is actually quite good and very relevant. It is just scares a few antivirus applications. If you ignore them, it does its thing quite well.
You could always use spice simulators. However, i find the emrfd software quicker and eaiser to use as it has everything setup for you.
There are times (when i needed to add a notch in the middle of a band pass) when emrfd suite wont do and you have to spice your way out of.
The algorithms for the emrfd are actually from IRFD. Someone with javascript chops could easily write us an online version of these. There are some gems in there that I don't see anywhere else, like the cascase calculator.

73 ,f

15445 2019-09-08 10:50:18 Rob Re: Supply decoupling resistor

IS the software available?

15446 2019-09-08 18:18:53 augustinetez Re: Supply decoupling resistor
No, the software is no longer available, it's been deleted from the ARRL site.

The last version was Ladpac-2008
15447 2019-09-08 21:44:45 Rob Re: Supply decoupling resistor

Is it illegal to copy and share it?

15448 2019-09-09 08:22:09 Zach Metzinger Re: Supply decoupling resistor
This is the main reason that I prefer open-source or freeware solutions, if possible.

Shareware or even commercially sold software helps no one after the author(s) quit supporting it. This leaves everyone in the lurch, trying to figure out what to do when no legal avenue exists to get the software.

Fortunately, we still have PUFF (Linux version, even!), LTSpice, Qucs, etc.

--- Zach

15449 2019-09-09 08:34:27 Dana Myers Re: Supply decoupling resistor
15450 2019-09-09 08:48:17 Jim Strohm Re: Supply decoupling resistor

If a tree falls in the woods and nobody hears it .... (source unknown, first recorded circa either 1710 or 1883)

Don't ask, don't tell.  (source unknown or nobody cares, circa 1994)

The less you say about copyright issues for discontinued or deprecated software, the simpler your life will be. 


15451 2019-09-09 08:51:22 Jim Strohm Re: CDROM w/ PDFs [was Re: Supply decoupling resistor]

As a technical publications professional since the early 1990s, I can tell you that a response like the one you received is typical of an overworked or understaffed pubs department that lacks one stellar performer who works miracles on a daily basis -- coupled with bloated management overhead that squelches every new good idea, or worse, impedes the implementation of new good ideas by assigning the same task to multiple disjointed staffers and/or contractors/consultants. 

Many places I've worked over the years, I was the miracle worker.  More than once I've had to tell my boss that they'd run out of miracles for the week.  Many times my boss didn't even know I worked a miracle, but at least once I kept a past-his-expiration-date writer on staff for an extra year.  I wish I'd done that a few more times.

The main reason I never worked for the ARRL was NOT that they were an extremely low pay for the region....

So, I am not surprised.  You should not bear ill will towards the ARRL at large.  If you want things to change, YOU can work there.  For my part?  It's too political for me at ARRL, and I've been on the November ballot here in Texas for U.S. Congress three times. 


15452 2019-09-09 09:40:05 k2lrv Re: Supply decoupling resistor
I am always baffled by the Copywrite laws and such on dated material and software, but it is what it is.  Not saying I would not mind having the CD contents.  I had owned the CD when I purchased the book &, CD, but it got lost during a move.  

15455 2019-09-09 11:11:31 jim Re: Supply decoupling resistor

FWIW ..Spectrum Software just released its "microCAP" simulator (ver. 12) as a free package ..Runs on wine/mint linux


15457 2019-09-09 17:50:12 Vern VanZ Re: Supply decoupling resistor

While I've only just installed it, I was off and running VERY quickly, building an oscillator using jfets (mpf102).  Seems to have a very complete library.  I'm nowhere near qualified to do a review, but found it very intuitive to use.  That might change once I attempt to run a simulation...

Thanks for sharing the link.
15458 2019-09-09 20:54:14 augustinetez Re: Supply decoupling resistor
That would be a question for Wes to answer.