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Friday, August 7, 2020

Mars: Book Review, Martian Propagation, Martian Moons as VHF Repeater Sites

In SolderSmoke #224 I mentioned the Mars Trilogy by Kim Stanley Robinson.   I found a book review in The New Yorker (see below).   In Red Mars they mention that there is no ionospheric propagation on Mars.  W1PJE and K1RID point out that this is incorrect -- there is ionospheric propagation on Mars.  K1RID provides a link to a really detailed NASA study of this question (it includes discussion of the effect on propagation of Martian dust storms -- good to know!). Finally, 2E0CHK suggests placing VHF repeaters on the two moons of Mars.  I found a good article about the overhead passes of these moons.   See below for all.  


Here's a review from The New Yorker

Hello Pete and Bill,

Listened to your latest SolderSmoke podcast. Enjoyable as always. But you should correct the record: Mars does have an ionosphere!

The peak daytime electron density ("M2 layer") is low in altitude - perhaps 130+ km, about our E region - and density is like our E region too (5-10x lower than our F region). So for the Mark Watneys carrying their Homebrew rig and inverted V, probably only a few hundred km to the first skip zone. More NVIS flavor than anything else.

Fun to think about. You should go and test it out!

Phil W1PJE

BTW, this made the rounds in our club last year:

dit dit

73 de Ed, K1RID
Newburyport Electronics & Radio Society


Hey Bill,
No skip on Mars ?
No ionosphere ?
Every cloud has a silver lining, even if Mars doesn't have any clouds ;)
Mars has two moons.
Could be paradise for Moon Bounce aficionados. No ionosphere or F layer to get in the way. VHF can get around corners after all.
Here is an article describing the overhead passes of the two Martian moons: 

Thursday, August 6, 2020

How to Sweep, Plot, and Measure Filter Output in LTSpice

The other day Pete N6QW posted a very nice graph of a bandpass filter's passband.  He was using LTSpice.  I realized I had a serious gap in my LTSpice knowledge -- I wasn't sure how to do this.

The charming video from India explains how.  Really useful.

Wednesday, August 5, 2020

OSCAR 100 Geosynchronous Satellite Video

I guess the title for this post could also be "How the Other Half Lives."  I'm sure at least a few of you will be thinking about building an OSCAR 100 station after watching this video.  But if you are in North or South America (with the exception of the Eastern tip of Brazil), forget about it.  OSCAR 100 is geostationary over the other side of the planet.  And amateurs have no equivalent on this side of the world.  But we can listen in using the Web SDRs. 

A couple of interesting bits from this recording.  You can hear G7BTP's coming back from the satellite with a bit of a delay -- he is obviously monitoring the downlink when he is transmitting.  DL8FBH says that he doesn't have a receive system of his own -- he is using a WEB SDR station (as I was) for the receiver. 


Monday, August 3, 2020

Homebrew Resistor Kit -- Drew's Mouser BOM

I put the resistors in parts envelopes and cardboard boxes

Hi Bill,

You mentioned wanting to get a resistor kit.  If you'd like, I can
help you do what I did.

Then I noodled about it a bit.  And looked at mouser.

A tiny bit of code put together a copy and paste list of part numbers
that I pasted onto mouser's BOM order form.  And bob's your uncle.

In my case, a particular manufacturer's 1/4 W metal film 100 ppm as
they were 1.9c @ 100 pieces.  I created a copy and paste BOM for E6
over 4 decades plus E3 for a 5th and 1M and 49.9 ohms. Less than $2
per value for 29 values.  Not a bad price for the size of the resistor
kit.  I also figured if the value gap was too large, I could fill it
in with the other half of the E12 series.  (E6 series is every other
E12 series value.)

This could be tweaked.  Perhaps fewer resistors in each value.  Or add
some more special values or whatever.

Mouser was kind enough to cut tape and put each value in a flat
plastic baggy with a label as to what was inside.  Sorted in a file
box, it's a snap to grab a resistor.
Perhaps this is something I should post online to share?  Maybe
someone else already has?

On my todo list is to construct my self a homebrew BOM of capacitors.

If you're interested, I could update this and let you know what Mouser
can do for you.  It may not be your preference, but it is an
interesting option.

Best regards,



Drew:   Your message caused me to think about what I really need in a resistor kit.  I have been using some other resistor kits, but I end up using ALL of certain values and NONE of others.  Your message made me realize that there is valuable data in those old kit packages.  

I took a look a them this morning.   It seems I use the following values:  4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k, and 10k.  That's about it.  So maybe I just need to go to mouser and order, 50 of each.  I'm thinking 1/4 or maybe 1/2 watt? 

The packaging you describe sounds great.  How can I get Mouser to do that for me?  

I don't think I need the more sophisticated approach you used, but I'm sure we have listeners who could benefit from it. 

Any further suggestions?  

Thanks again,  

73  Bill 

Hi Bill,

Sounds very good.  It turned out to be simple for me to order a
ridiculously well stocked resistor kit, but doing something custom is
actually a great idea.  If you want both 1/4 and 1/2, get both.  (I
figured I could always make a 1/2 W resistor out of 2 1/4 watt

The packaging is just what they do.  No extra charge other than their
regular shipping and handling.

So, I did this in late 2018.  When ordered, two values were
backordered, but they shipped them out a month or 6 weeks later or
something.  Checking now, 660-MF1/4DC1000F (a 1% 100 ohm metal film
1/4 watt), I see it is out of stock with an ETA of June 1st for 10K
they are ordering.  The other P/N that was backordered was
660-MF1/4DC1503F.  Who knew 100 and 150K ohms were extra popular?
150K is in stock right now BTW.  Maybe it's random what they run out

Best thing is you copy and paste your list of P/Ns and quantity for
each and bam Mouser will tell you pricing and if anything is
backordered, etc.  If you don't like what you see, change your list
and try again.

I actually thought about what I wanted, then looked at Mouser to see
what they had and what the pricing was on it.

So, from this particular resistor family, I see the pricing is what it
was a couple of years ago.

if you order 50 pieces of that 150 or 100 ohm resistor, that is:
50*$0.055 = $2.75 for 50 resistors.

If you order 100 pieces of that 150 or 100 ohm resistor, that is:
100*$0.019 = $1.90

IT"S CHEAPER TO ORDER 100!  Well, at least for this resistor family
and for Mouser's price breaks.  You have to look at the price breaks
versus volume.  And of course, understand the minimum you need and the
maximum you can store in your lab.  :-)  Don't be ordering 10,000.

So, price breaks for these they show:

Qty.    Unit Price
1    $0.23
10    $0.055
100    $0.019
1,000    $0.014
2,000    $0.009
10,000    $0.008
25,000    $0.007

You can see that there's a good break at 10, 100, and 2,000.  The
quantity with a good break really depends, so you would have to look
at different vendor product families to see.  I don't think I looked
very long.  I probably knew I wanted 1/4 W (may have considered 1/8 or
1/2, don't remember).  I also think I knew I wanted metal film.  When
I saw the pricing on these at 100 pc and with 1% tolerance (so I could
double out to E12 series and have it make sense if it turned out to be
useful for me), I stopped shopping.

Here's the full BOM I ordered.  The top part is some extra parts I
wanted and those couple of special resistor values.  The lower part
was generated by just a few lines of python:



So, your BOM (4.7, 10, 47, 100, 220, 330, 470, 1k,  2,2k, 3,3k, 4,7k,
and 10k) would be the following.  Added the 4.7 by hand and deleted
the other values by hand.  Qty 100 each.
-----  Services & Tools button.  BOM Tool button.  Login (they
want account for the tools.  I can't complain.)  Upload spreadsheet or
copy and paste.  In this case, copy and paste.  In fact, copy right
out of this draft email and into their tool.  Next.  Then they ask me
for a name for the BOM and if I only want RoHS.  (RoHS is up to you.
I picked only RoHS, because I know all these parts are RoHS and it
won't warn me about lead poisoning or anything.)  Process BOM.

I had the 4.7 wrong, but they figure it out.  Ouch.  Pricey.  Maybe
you don't need so many, but $4.6 for 100.  Parallel a couple of 10
ohm, you'll have less parasitic L in your emitter circuit.  Change the
BOM before you click the add all to cart.  No problem.  Or maybe 4.7
is worth the extra money to a high roller such as yourself.  :-)

2 parts are at 0 inventory.  The 100 we knew about.  470 as well with
6K arriving 15June.  Yes, those ETAs are perhaps questionable.  Dunno.
They will ship you what they have and ship the rest later AT NO EXTRA
CHARGE.  :-)

A third part is at 123 pc inventory.  Act now before they are all out!
:-)  220 ohms.  6K due end of June.

The above would be $25.50 plus less than $10 for their cheapest
shipping option.  Not a bad price for a well stocked CUSTOM kit and
it's really easy to do.  And these are good parts with specifications
and tempcos etc. all in the data sheet.  Sure, you don't need it 99%
of the time, but if you wanted it, because you were doing something
fussy, you have it.

You could cut that price down quite a bit if you went carbon or wider
tolerance.  (Who needs 1%?  This is electrical engineering, not
mechanical engineering!)  Or maybe another manufacturer.  It's easy to
browse on Mouser and figure out those other options quickly and what
it may do to help you out.  Of course, when you get to a price of
$0.00, you still have the flat rate cheapest Mouser shipping as the
floor on what price you can achieve.

Mouser will also give you a print and email with price, part number,
description of everything in your custom kit.  And each pouch is
labelled.  Crazy!  :-)

Another crazy thing is with these BOMs is that you can easily share
them with others.

Best regards,


Saturday, August 1, 2020

SolderSmoke Podcast #224: Mars. Spurs. Bikes. SDR. NanoVNA. Antuino. MAILBAG

SolderSmoke Podcast #224 is available:

1 August 2020

--The launch of Perseverance Mars probe with Ingenuity helicopter.
--China’s Tian Wen 1 on its way – radio amateur Daniel Estevez EA4GPZ is listening to it! 
--Sci Fi Books:  Mars Trilogy by Kim Stanley Robinson.  No skip on Mars :-(
--We have some sunspots!  SFI now 72 and the Sunspot number is 23. 

Bill's bench: 
--Conquering Ceramic Spurs in Q-31   Roofing filter -- sort of 
--NE602 for a Q-75 converter – Gilbert Cell. 
--Measuring low power levels out of NE602.  Antuino better than 'scope . 
--NanoVNA   Really cool stuff.  SDR in there. 
--Building a 455 kc LC filter from QF-1 rubble. Using LTSPICE, Elsie... 
--Reviving my bicycle AM radio – The “All Japanese 6”
--Understanding L Network impedance matching. 
--Bill’s new resistor kit from Mouser. Thanks to Drew N7DA. 


Pete's Bench: 
--Lockdown Special 
--BPF work on SDR Rig
--I U W I H 

VK3HN Summit Prowler 7
VK2EMU “The Stranger”
SM0P  HB uBITX in Dubai
AE7KI  Worked him in VK from London
ON6UU  EA3GCY’s 4020 rig
KA4KXX A Simpler Mighty Mite
KD4PBJ Radio Schenectady
W3BBO 12AU7 Regen
KE5HPY Another 12AU7 regen
N5VZH Ne602 Converter
KY3R Wall Art
G4WIF  Spectrum Analyzer in your pocket
W2AEW  Talks to UK Club
KK0S Sent 455 Kc IF cans
KL0S Making 9Mhz filters
VU2ESE  Diving into simple SDR schemes
Dean KK4DAS  Amateur Radio Astronomy

Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column