Re: Pulling Crystal Frequency in VXO
All,
I can make my Stand Alone VXO board available if folks are
interested in that approach.? Will work with any rig needing a VXO
to work with some IF.? Let me know? your interest and I can post the
Gerbers on my web site
72/73,
Jim, K8IQY
On 5/27/2025 6:10 PM, Doug Hendricks
via groups.io wrote:
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Are boards available for these transceivers
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Re: Pulling Crystal Frequency in VXO
Are boards available for these transceivers
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Re: AA7FO VXO Crystal Table, First Pass
John et al,
I must apologize.? I just mentioned the C language because I do all
my stuff in it.? It's a poke at the Python and CS computer language
wars.? Very sorry.
It was assumed on my part that everyone would use the app or adventure
into doing some programming in their language of choice to avoid
losing all that talent.
Again, sorry.
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On 5/26/25 19:20, John Kirk via groups.io wrote: For those of us not literate in C, you can do the same thing with an intermod calculator program - I use a freebee one called "PRFINTERMOD, freely available on the web.
John, VK4TJ
--
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: Pulling Crystal Frequency in VXO
Folks,
many years ago, Luc F6BQU designed "Le Forty", a 40 meter transceiver using a VXO. In order to enlarge the range he used two chokes in series but placed parallel to each other in the PCB, so the "adjustable" gap between them changed the mutual inductance and, thus, the range and stability.
You may see his "Forty" saga here: ?http://lpistor.chez-alice.fr/projetforty.htm
Any translator will help with the details.
jon, ea2sn
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Hi Mike
?
I've used the TL974 in several project without issue. I use it because it's very good value for money having quite low noise of 4 nV. It's main shortcoming is that it cannot source more than a few milliamps of current (but it can sink about 70mA) which isn't an issue where I have used them. An alternative is the TLV9164 which is noisier and costs about 3 times as much.
?
I guess you tried the TL974, had an issue, swapped it out and the issue went away? I find that 90% of noise can be attributed to layout and decoupling. I use 4 layer boards for all my projects now (apart from this one where I just could not route some of the longer traces so used 6 layers) where the two inner layers are exclusively ground plane and have had no issues. Of course there are several other key factors to get right but that was the main one.
?
73, Ian
VK7IAN
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Re: AA7FO VXO Crystal Table, First Pass
For those of us not literate in C, you can do the same thing with an intermod calculator program - I use a freebee one called "PRFINTERMOD, freely available on the web.
?
John, VK4TJ
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Re: VXO /IF combo schemes
My bad. I should have said NorCal 38S.?
Not sure our scope here includes thermion devices. (-: ?
?
Yes I referenced bulk acoustic wave filters on a chip as something I was engaged developing. In great contrast I worked for a few months in (yikes) CRT engineering. Back then RCA still made tubes, and transistors. Wow that was some era as I just escaped college in 1981. Oh I guess oscilloscopes back then had CRTs (okay let¡¯s admit I have an 80s HP scope here but rest is solid state).?
we can wonder if this 38S influenced the SST. I wonder how many published QRP transceivers featured a VXO? ?Some radars once used VXOs in their design, but in literature they are called VCXO.?
Curt
?
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Re: VXO /IF combo schemes
Oh, oops.? When I was refering to a 38S I was going further back
to the Hallicrafters tube receiver back in the 50s, the 1950s.
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On 5/26/25 14:12, Curt via groups.io wrote: On the 38S it was designed around that large IC that who knows its its still available. Otherwise it's a normal ne602 type transceiver.
That vxo and IF combo meanwhile are useful. I recall my rig tunes from 103 to 122 kHz. Looked at schematic and I see the RF choke in series with the crystal, and a makeshift varactor. Hey that particular part will determine what tuning range is obtained, mine turned out more ideal.
I don't know how many qrp cw transceivers go as high as a 12 MHz IF. Note bandwidth tends to scale with IF, so a bit wide. One can follow it with a nescaf or other narrow audio filter.
These types of rigs were cat's meow when most of us were limited to single band home constructed rigs. Now it's mere interest to play with these when you have something like a QMX around.
--
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: VXO /IF combo schemes
On the 38S it was designed around that large IC that who knows its its still available. Otherwise it's a normal ne602 type transceiver.?
?
That vxo and IF combo meanwhile are useful. I recall my rig tunes from 103 to 122 kHz. Looked at schematic and I see the RF choke in series with the crystal, and a makeshift varactor. Hey that particular part will determine what tuning range is obtained, mine turned out more ideal.?
?
I don't know how many qrp cw transceivers go as high as a 12 MHz IF. Note bandwidth tends to scale with IF, so a bit wide. One can follow it with a nescaf or other narrow audio filter.?
?
These types of rigs were cat's meow when most of us were limited to single band home constructed rigs. Now it's mere interest to play with these when you have something like a QMX around.?
?
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Re: Pulling Crystal Frequency in VXO
All,
If I were to build an SST or similar rig for 20-Meters, I would use
the following crystals.? IF, 3.932 MHz crystals, Mouser part number
520-HCA393-17X and for the VXO, 18 MHz crystals, Mouser part number
520-HCA1800-20X.? I'd use 3 of these crystals in parallel for
maximum pulling range and fiddle with the value of the series
inductor to get the widest, most stable range.? My guess is that at
least 25KHz of tuning will be available.
72/73 and have fun,
Jim, K8IQY
PS, both of these crystals are in the larger, desirable HC-49 case.
On 5/26/2025 12:56 PM, chuck adams via
groups.io wrote:
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Found
the following on the internet for those interested in such stuff
for the
SST project.? FYI and shown without any attempt at organization.
The following shows quantitative results using two crystals in
parallel for a few crystal freqs.
? Note the
higher the VXO frequency and the range.
NB6M article from NorCal QRP Club site.
For those that want instant gratification, here are a few videos.
Interesting YouTube video showing 10.111MHz crystals for 30m
? links to more videos
from VK3YE.
I haven't the time right now to scrape YouTube from end to end in
a search.
FYI and hope you find something you can use.
|
Re: AA7FO VXO Crystal Table, First Pass
Thanks for the great info Chuck.
Good job on your C program.
This will definitely help me out and I appreciate it.
73,
Alan, N8WQ
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On 5/26/25 15:49, chuck adams via groups.io wrote: If I did it, do I get to name it?? :-)
I went to Aliexpress and ebay and looked up available crystal frequencies
for off the shelf values.? I cheated and added one more frequency from
the 1W values (22.040MHz) as a double check for 40m.
I wound up with 49 values, shown here so you can cut and paste or use
as you see fit.? Even add values that you find.? I did not go to
Digikey or Mouser as I did not want to spend hours on this.? Spent
less than 30mins, so you get what you pay for.
?1.843? 2.000? 2.457? 3.276? 3.579? 4.000? 4.096? 4.433? 4.500 4.897? 4.915
?5.000? 5.529? 6.000? 6.745? 7.200? 7.372? 8.000? 8.192? 9.380 9.815 10.000
10.245 11.059 12.000 12.288 13.560 14.318 14.745 15.000 16.000 16.934 18.000
18.432 20.000 21.477 22.118 24.000 24.576 25.000 26.000 27.000 30.000 32.000
32.780 33.868 36.000 40.000 23.040
Wrote a quick little ditty in C and here is what I get.? FYI and hope it
helps.? I only did 40m to 10m for the first pass, including the WAR bands.
? ham freq??? crystal? crystal
?? 10.103???? 4.897??? 15.000
?? 10.118??? 12.000??? 22.118
?? 14.105???? 7.372??? 21.477
?? 14.118???? 8.000??? 22.118
?? 21.040???? 2.000??? 23.040
?? 21.085???? 4.915??? 26.000
?? 21.103???? 4.897??? 26.000
?? 21.197???? 1.843??? 23.040
?? 28.157???? 1.843??? 30.000
?? 28.280???? 4.500??? 32.780
??? 7.040??? 16.000??? 23.040
??? 7.059???? 4.000??? 11.059
??? 7.066??? 16.934??? 24.000
|
Re: VXO /IF combo schemes
Curt,
Thanks for the info and your observation about selectivity.
I am looking at the 38S schematic.
It is an interesting design.
73,
Alan, N8WQ
On 5/26/25 14:51, Curt via groups.io
wrote:
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Alan
?
Some info here. Presuming industry may still have these
crystals.?
?
?
Did my search on qrp vxo if combinations?
?
Note when IF must go up there is compromise in selectivity.
However bands tend to be empty enough the 38S might do just fine
with its very compromised IF. With its poor sideband image
suppression I recall using it to work Split with 1.5 kHz
offset.?
?
Curt
?
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VXO Crystal Table posting correction
1.? It's the WARC bands.? Typo on my part.
??? I'll send back my UIL typing championship trophy.
??? Now you know why my postings are so long.? :-)
2.? I restricted the band search to the CW bands.? There is
??? the possibility that some combos generate digital
??? and voice band frequencies.
tnx es 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
|
AA7FO VXO Crystal Table, First Pass
If I did it, do I get to name it?? :-)
I went to Aliexpress and ebay and looked up available crystal frequencies
for off the shelf values.? I cheated and added one more frequency from
the 1W values (22.040MHz) as a double check for 40m.
I wound up with 49 values, shown here so you can cut and paste or use
as you see fit.? Even add values that you find.? I did not go to
Digikey or Mouser as I did not want to spend hours on this.? Spent
less than 30mins, so you get what you pay for.
?1.843? 2.000? 2.457? 3.276? 3.579? 4.000? 4.096? 4.433? 4.500 4.897? 4.915
?5.000? 5.529? 6.000? 6.745? 7.200? 7.372? 8.000? 8.192? 9.380 9.815 10.000
10.245 11.059 12.000 12.288 13.560 14.318 14.745 15.000 16.000 16.934 18.000
18.432 20.000 21.477 22.118 24.000 24.576 25.000 26.000 27.000 30.000 32.000
32.780 33.868 36.000 40.000 23.040
Wrote a quick little ditty in C and here is what I get.? FYI and hope it
helps.? I only did 40m to 10m for the first pass, including the WAR bands.
? ham freq??? crystal? crystal
?? 10.103???? 4.897??? 15.000
?? 10.118??? 12.000??? 22.118
?? 14.105???? 7.372??? 21.477
?? 14.118???? 8.000??? 22.118
?? 21.040???? 2.000??? 23.040
?? 21.085???? 4.915??? 26.000
?? 21.103???? 4.897??? 26.000
?? 21.197???? 1.843??? 23.040
?? 28.157???? 1.843??? 30.000
?? 28.280???? 4.500??? 32.780
??? 7.040??? 16.000??? 23.040
??? 7.059???? 4.000??? 11.059
??? 7.066??? 16.934??? 24.000
--
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: VXO /IF combo schemes
Alan
?
Some info here. Presuming industry may still have these crystals.?
?
?
Did my search on qrp vxo if combinations?
?
Note when IF must go up there is compromise in selectivity. However bands tend to be empty enough the 38S might do just fine with its very compromised IF. With its poor sideband image suppression I recall using it to work Split with 1.5 kHz offset.?
?
Curt
?
|
Gang,
Has anyone created a excel spreadsheet where one can experiment by either plugging in given crystal frequencies for the VXO and IF per Band or a table of popular crystal frequencies? Just curious. I will keep my fingers crossed! :)
Alan/N8WQ
|
Ask and ye shall receive:
<>
The equations that I derived while a student were about
1962.? Eons ago.
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On 5/26/25 09:33, Alan N8WQ via groups.io wrote: Hi Chuck,
Is there some way we can get a copy of your article?
Thanks...
Alan, N8WQ
--
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
|
Pulling Crystal Frequency in VXO
Found the following on the internet for those interested in such stuff for the
SST project.? FYI and shown without any attempt at organization.
The following shows quantitative results using two crystals in parallel for a few crystal freqs.
<>? Note the higher the VXO frequency and the range.
NB6M article from NorCal QRP Club site.
<>
For those that want instant gratification, here are a few videos.
Interesting YouTube video showing 10.111MHz crystals for 30m
<>
<>? links to more videos from VK3YE.
I haven't the time right now to scrape YouTube from end to end in a search.
FYI and hope you find something you can use.
--
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
|
Hi Chuck,
Is there some way we can get a copy of your article?
Thanks...
Alan, N8WQ
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On 5/24/25 18:32, chuck adams via groups.io wrote: Ordered another set of 10 boards.? Here is what I get billed for.
Subtotal: ? ? ? ? ?? $ 5.00
Shipping Cost: ? ? ? $ 6.34
Paypal Fee ? ? ? ? ? $ 1.17
Duty & Tax:vat help? $ 8.00
All Total?? ? ? ? US $20.51
I still don't mind paying $2 per board, but someone
is getting some extra money somewhere in the chain.
They still thinking that the 145% tariff is still
in play?? Is it?
Just wondering.
The board is a combo of the G3UUR scheme and my
article in QEX some time ago as K7QO.? I'll
publish the Gerbers as soon as I am sure I
won't get burned at the stake for any major
errors.? :-)
|
Ian,
?
What is your experience with using TL974 in the AF gain stage? When I tried those, the clicking sound from WiFi detection was very annoying. This seems to be a "feature" of the whole TL97x family. Maybe not a problem when using the receiver outdoors or just away from computers.
Also the output impedance of TL974 is 1.5k, so loading with less than that (U8.1, U8.3) is not a good idea.
?
73, Mike AF7KR
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Jim Kortge, K8IQY
Alan N8WQ
