Yes, we wanted to save money
|
Forgot.
Note, in the SST, Wayne went with molded inductors.? When NorCal
did this (and Doug can verify) I'll bet that molded inductors
were much cheaper than toroids. They do heat up as a side note.
I reserve the right to go with toroids to get the optimum
range.
In the 1W and 5W, Diz went with toroids.? He had the world
supply of them.? Look at the inventory at KitsAndParts.com
that Mike has on hand.? I just placed a significant order
for ones that I need and want to use.? The rigs used
toroid inductors because you can wind to the optimal
inductance value you need for maximum tuning range
you can get out of the crystal critters.? Less heating
with larger surface area for heat dissipation using
largest wire you can wind and get the turns you need.
OK.? I carry on too much.? I know.
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
PA,CA,CO,WI,NE,ID,IL,NC,NY,WV
MA,OH,OR,RI,MT,WY,WA,MI
DXCC W,VE,JA,PY,ZL,TX9
|
Re: Crystal Searching[long]
This is not an easy answer.? It is mathematically, but there are some
variances between manufacturers and quality control.? Let me explain.
The series resonant frequency of the crystal is determined by
L_1 and C_1, the motional parameters due to the physics.
In a VXO, we are interested in just how far we can "pull" the
frequency of operation, say delta_f.? We can approximate this
value by the formula:? (Colpitts oscillator is typical)
delta_f ~= 0.5*(L_ext/L_1 - C_1/C_ext).
L_1 and C_1 we can't do anything about.? It comes with the
crystal as it is manufactured.? In both the SST and 1W
transceivers, look at the schematics.? What do you see
in series with the crystal.? Yep.? An inductor, let's
call that L_ext and a variable cap C_ext.? L_ext is
fixed.? As you vary C_ext, you shift the frequency.
At first you say, well heck let's make L_ext large
and C_ext large.? Several things happen.? You can't
shift far (L is fixed) and L_ext swamps the capacitance change.
A bad side effect is that the oscillator stability
goes to heck in a hand basket.
This leads up the answer for the question.? I have
to take the different frequencies, different varactor
diodes, different molded inductors and transistors
(2N3904, 2N4401, or even a JFET) and see what gives
the greatest range for each band, greatest output
and if that is good at the output of the mixer,
least drift, ....? You see the problem, but I
have the fixture set up on a Manhattan layout.
As soon as I get the crystals off the boat, I will
do the experiments and report to the group.? In the
meantime, maybe some of the group can also give
their results from previous builds and lab work.
Look at the frequency range of the specs of every
rig that uses a VXO.? This may help you see just
how much you can in tunable range of the VXO.
Get out the G3UUR and measure the L and C values.
R_1 of the crystal is also at play in the
range of frequency pull you can get and a large
R_1 will get you drift due to heating.
Since we are getting these things from China, there
may be a spec sheet that gives some ranges, but
crystal axis cutting and accuracy causes some variance
between batches.? That's why you buy crystals in bulk.
They come from the same batch and setup and you are
more likely to get a close match more easily.
We used to see a date code, but with the HC-49/S,
there is no room and the new crystals rarely show
a batch code like transistors.
BTW, the HC-49/S and the HC-49/U should have almost
the same L_1 and C_1 values.
Go to K8IQYs home page and go to the crystal page
values he has measured.
<>
L_m and C_m are the L_1 and C_1 variables used in
the formula.? You will see both sets of variables spread
across the Internet.? L_m and C_m are the ones used
by the industry.? I'll make up a table and put it on the
web for my results to add to the body of knowledge to
be found on crystals.? Maybe W7ZOI has some values also on
the web.
If the circuit capacitance across the crystal matches the
C_o value, then the circuit should resonant at the frequency
marked on the crystal in parallel mode.
This is just the tip of the iceberg.....
FYI
toggle quoted message
Show quoted text
On 5/23/25 14:29, Alan N8WQ via groups.io wrote: Thanks for posting this info Chuck.
I want to build a 20M SST so I am thinking of going with your VXO/IF scheme of 10MHz/4.032MHz
What are the advantages of using HC-49S, HC-49U or HC-49UX crystal types?
Looking at the CTS crystal datasheet I see that for a 4.032 MHz crystal there are two different load capacitance types listed: series or 20pf, what does that mean?
How would series or 20pf type crystal types affect the frequency bending of a CTS 10.000 MHz crystal?
Please excuse my ignorance of this subject. I am having fun learning!
Alan, N8WQ
On 5/23/25 12:51, chuck adams via groups.io wrote:
Gang,
For those that haven't stocked up over the years on crystal
deals or renewing their stock like I am, here is a list
for you to go through at your time of choice.? If you
are interested, I'd recommend you do so rapidly as the
climate is a changing.? See the 4.032 and 10.000
vendor and what I got before things changed.
Presented here to save you time that I spent on
searching the web and I just got the tip of the
iceberg.? Share if you have better deals.
------------------------
<>
?? o? about $0.64 per critter for 10 with free S&H
?? o? I've ordered here and was happy and you get
????? them quick.
<>
?? o? I got my 4.032 and 10.000MHz here when it was
????? free shipping!? But, the $50 S&H is ridiculous
????? now.? He did it after the trade wars started.
List of vendors I've ordered from and some are on
the boat as we speak.? I'll come back with reports
when I receive them, but I show them here as a
current status in case the vendor later decides to
change things for the worse.?? This list is for the
small gamblers among us.? I went out on the limb
on this one.? I'm not responsible for being the
village idiot.
<> 14.318MHz
<> 15 freq options
<> 10 freq options
<> a bunch!
<> options
And while I'm wasting your time, take a look at how much quartz
is being manufactured.? Quartz crystals are used in more places
than you think about.? Enjoy.? I know that I do for this one.
Things start at 3:00 or so on the factory floor.
<>
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
PA,CA,CO,WI,NE,ID,IL,NC,NY,WV
MA,OH,OR,RI,MT,WY,WA,MI
DXCC W,VE,JA,PY,ZL,TX9
|
Thanks for posting this info Chuck.
I want to build a 20M SST so I am thinking of going with your VXO/IF
scheme of 10MHz/4.032MHz
What are the advantages of using HC-49S, HC-49U or HC-49UX crystal
types?
Looking at the CTS crystal datasheet I see that for a 4.032 MHz crystal there are two different load capacitance types listed: series or 20pf, what does that mean?
How would series or 20pf type crystal types affect the frequency bending of a CTS 10.000 MHz crystal?
Please excuse my ignorance of this subject. I am having fun learning!
Alan, N8WQ
On 5/23/25 12:51, chuck adams via
groups.io wrote:
toggle quoted message
Show quoted text
Gang,
For those that haven't stocked up over the years on crystal
deals or renewing their stock like I am, here is a list
for you to go through at your time of choice.? If you
are interested, I'd recommend you do so rapidly as the
climate is a changing.? See the 4.032 and 10.000
vendor and what I got before things changed.
Presented here to save you time that I spent on
searching the web and I just got the tip of the
iceberg.? Share if you have better deals.
------------------------
?? o? about $0.64 per critter for 10 with free S&H
?? o? I've ordered here and was happy and you get
????? them quick.
?? o? I got my 4.032 and 10.000MHz here when it was
????? free shipping!? But, the $50 S&H is ridiculous
????? now.? He did it after the trade wars started.
List of vendors I've ordered from and some are on
the boat as we speak.? I'll come back with reports
when I receive them, but I show them here as a
current status in case the vendor later decides to
change things for the worse.?? This list is for the
small gamblers among us.? I went out on the limb
on this one.? I'm not responsible for being the
village idiot.
14.318MHz
15
freq options
10
freq options
a
bunch!
options
And while I'm wasting your time, take a look at how much quartz
is being manufactured.? Quartz crystals are used in more places
than you think about.? Enjoy.? I know that I do for this one.
Things start at 3:00 or so on the factory floor.
|
Re: Accurate way to measure RF power??
All,
?
??? I am making my measurements at 14.050 MHz.?
?
???? I recognize this is a QRP site, but I'm trying to measure a wide range of power: mW to 100+W.?
?
???? The measurements I've made so far have all been terminated with commercial dummy loads of 50 ohms, and all of the probes, operated on X10, have been properly compensated.? I made a "port" that allows me to clip the probes onto the coax center conductor while clipping the probe's ground to the shield of the coax between the transmitter and load.
?
???? My scope displays Vrms and it agrees with the actual trace amplitude.? I plug that into the formula Vrms^2/50 to determine power.? When using the simple diode detector I made, I assume what I'm reading is very close to Vpeak, so I use the formula Vpeak^2/100 when using it.
?
??? My gut says that the simple diode detector should provide some very accurate readings of Peak Voltage (within the limits imposed by the power level and diode selection) that can then be computed into power very easily.? Opinions:? would a 1N4007 be OK to detect/rectify 100W??
?
???? However, I will try again to compensate all of the probes more carefully, and use the included Probe-to-BNC adapter I recently discovered to eliminate any impedance bumps I may be introducing by clipping the probes onto my homebrew "port".
?
???? Given a choice, I'd rather use the scope for its wider voltage handling capability than a diode detector, but if I can't easily resolve the scope's inaccuracy, I'll have to rely on a couple of diode detectors using different diodes for the varying power levels.
?
Bill
W2EB
East Syracuse, NY
?
?
|
Re: Is there an easy way to test sa612 smd chips
I found three different types of DIP 602s in my stash.? Signetics
SA602N, 1989 date code, 22.3 kohms; Philips SA602AN, can't
decipher date, 11.2 kohms; NXP NE602AN, can't decipher date, 11.5
kohms.
I suspect manufacturers have their own somewhat different fab of
these chips which accounts for the differences, and has nothing to
do with specific package type.
Steve AA7U
On 5/23/2025 8:54 AM, Dave AA7EE via
groups.io wrote:
toggle quoted message
Show quoted text
On Thu, May 22, 2025 at 01:50 PM, Steve Ratzlaff wrote:
I tested 7 SMD "NXP" marked 612's just now (old Fluke DMM
set to 200 kohm scale):
ohmmeter reading across pins 1 and 2:? 11.1k; 11.6k; 11.4k;
11.0k; 11.3k; 11.3k; 11.5k ohms.
Steve
I have a number of SMD Signetics SA602A's. I don't want to
remove them from the roll, but I do have one free one and one
single solitary 8 pin DIP one. The SMD one measures 11.75K DC
resistance across pins 1 and 2, while the 8 pin DIP part
measures 21.65K. Seeing that Steve's SMD ones all measured in
the 11K range, as mine did, I'm wondering if the through-hole
ones tend to all measure higher across pins 1 and 2?
?
No particular reason for me asking; I just noticed it. Back
to your regular programming :D
?
Dave
AA7EE
|
Re: QRP power measurement and AA7FO lab and web report[long]
Hey you were the guy advocating that a vxo offers enough tuning span (-:
?
The pll does add complexity needing microcontroller and display. Enough to warrant getting a qcx mini instead.?
?
I recall kitsandparts having si5351 hardware and code.?
?
Vxo are more nice when the xtal combo pushes it up in frequency. Like the 38S design that can cover much of the 30m cw span.?
?
|
Gang,
For those that haven't stocked up over the years on crystal
deals or renewing their stock like I am, here is a list
for you to go through at your time of choice.? If you
are interested, I'd recommend you do so rapidly as the
climate is a changing.? See the 4.032 and 10.000
vendor and what I got before things changed.
Presented here to save you time that I spent on
searching the web and I just got the tip of the
iceberg.? Share if you have better deals.
------------------------
<>
?? o? about $0.64 per critter for 10 with free S&H
?? o? I've ordered here and was happy and you get
????? them quick.
<>
?? o? I got my 4.032 and 10.000MHz here when it was
????? free shipping!? But, the $50 S&H is ridiculous
????? now.? He did it after the trade wars started.
List of vendors I've ordered from and some are on
the boat as we speak.? I'll come back with reports
when I receive them, but I show them here as a
current status in case the vendor later decides to
change things for the worse.?? This list is for the
small gamblers among us.? I went out on the limb
on this one.? I'm not responsible for being the
village idiot.
<> 14.318MHz
<> 15 freq options
<> 10 freq options
<> a bunch!
<> options
And while I'm wasting your time, take a look at how much quartz
is being manufactured.? Quartz crystals are used in more places
than you think about.? Enjoy.? I know that I do for this one.
Things start at 3:00 or so on the factory floor.
<>
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
PA,CA,CO,WI,NE,ID,IL,NC,NY,WV
MA,OH,OR,RI,MT,WY,WA,MI
DXCC W,VE,JA,PY,ZL,TX9
|
QRP power measurement and AA7FO lab and web report[long]
QRP Power:
See <> manual for
how it is done with a dummy load.? Unfortunately QRPGuys are
shut down for a month due to traveling on vacation.
The power formula on the PCB is very very easy to derive
and easy to compute on your phone calculator.? $20 is
pretty cheap for thing IMHO.? I'd like them to change
the pin out to allow a two pin Arduino cable to be
used with the center pin on the board going to ground.
Makes it easier for me, and I like easy.
AA7FO Web Page:
Because of the security notice threat that was coming
up on my old web page, I have moved it.
<>
Note that I have revived some of my legacy writings
on Manhattan construction, 1W and 5W building guides
for those of you still hoarding the unbuilt kits
in secret storage locations.? The money I save I'll
donate to qsl.net to keep them going.? Not a friend
of money for nothing and chicks for free, as the
song goes.? I'm trying to get time to get back to
writing, but its more fun to build and operate.
I'll let you know how my combo of 10.000MHz(VXO) and
4.032MHz(IF) work out.? I'll measure the MDS with the
old S1-S9 generator from NorCal and report back first
thing.? You still have yours?? Battery check.
AA7FO YouTube Status:
Lost use of my video camera after 20 years of faithful
service, so if you are a vlogger, let me know offline
(I'm sure this group isn't interested in how to do it)
what a good deal is.?? Too many options on amazon.com.
Want one with macro capability for the closeups of
boards etc.
Manhattan Build:
Awaiting QRPMe pads to get the SST build going.
FYI.? If you look at the crystals needed, some
are very hard to find.? But, look at the 1W
frequencies in the retired kits on kitsandparts.com
for easy frequency combos to find on ebay and aliexpress
for less than a quarter a piece in quantities
of 10 with free shipping.? Search the isles for
what you need.? 40m is the tough combo.
Experimental Venture:
Someone in this group can open source a technique
for using the cheap Si5351 module to replace the
VXO and allow us to use any on hand crystals
for the IF we want with the usual caveats on
birdies.? May already be available from unknown
source previously written up.
FYI
dit dit
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
PA,CA,CO,WI,NE,ID,IL,NC,NY,WV
MA,OH,OR,RI,MT,WY,WA,MI
DXCC W,VE,JA,PY,ZL,TX9
|
Re: Accurate way to measure RF power??
Hello Bill,
I almost did not want to respond because I consider myself a "novice" still around all these experts.? But I decided to write anyways.? Just consider what I say with a grain of salt.
?
I used to get a lot of private emails from a big Elmer on here named Chuck Carpenter (SK).?? He was a big fan of the diode peak detectors and "RF taps" to measure RF power.? I wish I still had his emails.
?
Take a look at the RF probe from qrpguys.com
And they have an attenuator at qrpguys.com as well approved by Chuck as well.? The 10/20/30dB 50ohm attenuator.
?
kc9on had a smt version of a rf peak detector/dummy load for QRP.? i built it.? my first SMT project.?? Not sure why KC9ON stopped making this kit.
?
You probably know this already, so just ignore me for the silly questions:
- Did you compensate your probes?
- Lose connections on the cable?? (has been issue for me in the past)
- Cat or dog bite your cable?? (has been issue for me in past as well)
- 1M Inputs??? (Most scopes do not have 50ohm inputs)
- Probes and Scope on correct setting of 1X vs 10X setting?
- If scope is 100 MHz, are you using 100MHz probes?
?
What frequency are measuring?
?
Unless, you have 50-ohm inputs, they can only take so much power, so you may need to attenuate via an attenuator.? Best to read the manual to know how much the oscilloscope can take.
?
I know in the Electronics of Radio book for NorCal 40A CW Transciever Kit for the Questions.? It wanted to use instead of a probe, a BNC tee - one end to scope and the other to a 50-ohm termination (dummy load).
?
73 Daniel KK4MRN
?
?
?
|
Re: Is there an easy way to test sa612 smd chips
On Thu, May 22, 2025 at 01:50 PM, Steve Ratzlaff wrote:
I tested 7 SMD "NXP" marked 612's just now (old Fluke DMM set to 200 kohm scale):
ohmmeter reading across pins 1 and 2:? 11.1k; 11.6k; 11.4k; 11.0k; 11.3k; 11.3k; 11.5k ohms.
Steve
I have a number of SMD Signetics SA602A's. I don't want to remove them from the roll, but I do have one free one and one single solitary 8 pin DIP one. The SMD one measures 11.75K DC resistance across pins 1 and 2, while the 8 pin DIP part measures 21.65K. Seeing that Steve's SMD ones all measured in the 11K range, as mine did, I'm wondering if the through-hole ones tend to all measure higher across pins 1 and 2?
?
No particular reason for me asking; I just noticed it. Back to your regular programming :D
?
Dave
AA7EE
|
Re: Accurate way to measure RF power??
What type of scope do you have? I have a new Hantek and older Tektronik scopes and both are accurate for the HF bands. I like to use a scope because you can measure SSB PEP power.
The issue I have with the Tek scopes are the old probes. The clip-on hook adapters make intermittent contact with the tip so I made an adapter to connect the rig and the dummy load directly to the tip and ground sleeve of the probe.
If your scope has a 50 ohm input you can attach an attenuator with the appropriate power level and attenuation and bypass the probe.
I do lots of portable operation and picked up one of these portable scopes. It is accurate up to 30 MHz. The voltmeter function is helpful but the function generator has a very limited range.
Good luck.
Mike N2MS
toggle quoted message
Show quoted text
On 05/23/2025 4:10 AM EDT Bill <bill@...> wrote:
All,
Would a simple diode detector be a (relatively) accurate way to measure RF power?
I suspect my o'scope is reading RF incorrectly. I have 4 different x10 probes and with each one I get dramatically different results, up to a 30% difference. So, I can't trust my scope!!
Thus, measuring RF power presents a problem to me. I don't have access to any calibrated power measuring devices, but am quite confident of the calibration of my DVM.
Or, if diode detectors are inaccurate, do any of you have any tried and true ways to measure RF power with a decent degree of accuracy...say within 10%?
W2EB
Bill Lazure
|
Nice - - so how's the opposite side-band rejection?
?
KI4IO
Jerry W
Warrenton, VA
|
Re: Accurate way to measure RF power??
Hi Bill,
?
You didn't tell us what frequency range you were trying to measure, and what power range.? ?This can make a difference in how you can measure accurately.? ?Also, are you trying to measure the RF power that is already being terminated into a 50 ohm load?? ?If you were trying to measure with a 'scope you would have needed to do this as the scopes have high impedance inputs.
?
You're attempt with your oscilloscope will work assuming that you're probes are working correctly, and you scope bandwidth is wide enough to measure the RF energy directly.? ?If you have a Rigol scope of something similar, you're scope might have a calibration point on it that you can use to test your scope probe for both amplitude and correct compensation.? ? On the Rigol 'scopes is to the right of the BNC input connectors.? ? It should not be that hard to determine which probes are working correctly.? ?This is a common problem, as probes take a lot of abuse!
?
Your idea for using an RF probe is also a good one and allows you to measure the RF energy as a voltage.? ?One thing to keep in mind is that a diode detector provides a peak voltage, which needs to be converted to RMS voltage as part of the power calculation.? ?This is important if you're using a voltmeter (or oscilloscope)? to measure the detector output directly.? ? ?Curt mentioned a circuit by W7ZOI, who is always a great source of information.? ?HIs book Experiential Methods in RF design shows a simple QRP power and an RF? probe on page 1.16.? ? ?W7ZOI also published an accurate power meter in the June 2001 QST that uses a modern logarithmic detector IC for a wide range power meter.? ? I would recommend this article along with the EMRD information as he shows various methods for setting up a power meter into the RF Chain.??
?
Let me know if you have trouble finding? any of these references.? ? ? ?
?
73
Jim N8CH
?
?
?
|
Re: Accurate way to measure RF power??
Bill
?
I am surprised with scope probe inconsistency and don't know them well enough to comment. Maybe they are optimal at different frequencies.?
?
I built a diode sensor per W7ZOI instructions. It was embedded in a QST Article on a transceiver. Maybe it's also online. Uses a silicon diode for few watt measurements, and if needed a as second Schottky diode for lower levels. I certainly think it's accurate to better than 10 percent mostly determined by diode forward voltage variation. Built with a coax connector for its input. Certainly good for HF.?
?
For measuring very small RF power someone designed an accurate with a specific op amp. I sense you don't need it for this application. I recall this was Joe of njqrp.?
?
Let me know via direct email ic you can't find it.?
?
Curt
?
|
Accurate way to measure RF power??
All,
?
???? Would a simple diode detector be a (relatively) accurate way to measure RF power?
?
???? I suspect my o'scope is reading RF incorrectly.? I have 4 different x10 probes and with each one I get dramatically different results, up to a 30% difference.? So, I can't trust my scope!!
?
???? Thus, measuring RF power presents a problem to me.? I don't have access to any calibrated power measuring devices, but am quite confident of the calibration of my DVM.?
?
???? Or, if diode detectors are inaccurate, do any of you have any tried and true ways to measure RF power with a decent degree of accuracy...say within 10%?
?
W2EB
Bill Lazure
?
?
?
|
Hi Everyone
?
I've been working on a new transceiver project. I was so pleased with the uPDCR (a small phasing receiver with AI voice) that I thought it would be fun to turn it into a transceiver. So I've combined the transmitter section from the iqSDR40 with the uPDCR and built the uP40 (links below).
?
I really wanted it to fit into the next size up Hammond case which is 80x54 mm, so the PCB needed to be 80x50 mm. Instead of using the usual bifilar transformers wound on FT37-43 toroids, I thought I'd try a small surface mount common mode choke. Also thought I'd try one of the small surface mount RF MOSFETs designed for VHF, UHF the AFT09MS015N. I was very surprised and happy that all the components fit on the PCB! The uC and PWM filter parts are on the bottom and everything else is on the top. Then I started routing. I've pretty much standardised on using 4 layer boards but it became obvious pretty quickly that there was no way to route some of the longer traces because of the density of the components. OK, so I had a look at prices for 6 layer boards from JLC PCB and it's really not bad. So top layer is for RF signals, layer 2 is ground, layer 3 is for some uC control signals, layer 4 is 5 volts, layer 5 is ground and the bottom layer is mostly for digital signals. All layers also have ground and there are plenty of stitching vias. In the end I got 5 boards for about US$5 (shipped to AU) with a discount applied.
?
I built the transmitter section first and tested it with a signal generator. It worked fine. Got 5 watts. So the MOSFET and the common mode choke worked fine at HF!
I also updated the firmware to announce the mode and the frequency step.
?
uP40:
uPDCR:
iqSDR40:
?
?
?
73, Ian
VK7IAN
|
The Las Vegas seller of the good 2SC2078 I've tested shows 25 available again, if anyone has not yet stocked up on them--and the price is the same $2.10 each.??? :)
73,
Steve AA7U
|
Re: Is there an easy way to test sa612 smd chips
Thanks Steve.? Great to know.? ?Simple and easy.? ?I appreciate your knowledge.? ?Doug
|
Re: Is there an easy way to test sa612 smd chips
I found this at Adafruit.com as a soic-8 ic socket
but i am thinking of using as a tester.??
?
but this item only works for a size of 200... who knew there are different sizes of soic-8 ICs?
?
?
Here is another one, but it is expensive.
?
But if you have a whole bunch you need to test.
?
Last time I was considering of buying one, they sold out.? But they are in stock now.
?
73 Daniel KK4MRN
?
|
Alan N8WQ