|
Hi:
I am going to build some HF bandpass filters, in the range 1Mhz to 54Mhz.
Since most standalone filters are fitted with SO-239 sockets, I would use
reasonable quality SMA to PL-259 male cables, and want an SO-239 calibration
socket set.
What are people using for this type of work on HF ham gear? At these low
frequencies, it seems like the amount of effort in the following document:
might be overkill? Have people found simpler (less work) methods to get
adequate results for tuning a bandpass filter at frequencies less than 50Mhz?
Cheers,
Neal
|
There are many good reasons why there are not 'cal. standards' available in
the 239/259 formats. These connectors are not used or recommended in
professional circles - those which may require good cal. standards. SMA,
N, and BNC are the norm there, not 239/259's.
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Feb 25, 2020 at 12:14 AM Neal Pollack <nealix@...> wrote: Hi:
I am going to build some HF bandpass filters, in the range 1Mhz to 54Mhz.
Since most standalone filters are fitted with SO-239 sockets, I would use
reasonable quality SMA to PL-259 male cables, and want an SO-239
calibration
socket set.
What are people using for this type of work on HF ham gear? At these low
frequencies, it seems like the amount of effort in the following document:
might be overkill? Have people found simpler (less work) methods to get
adequate results for tuning a bandpass filter at frequencies less than
50Mhz?
Cheers,
Neal
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
|
Neal,
Here is one way to make your own SO-239 cal set.
Roger
|
David:
You are mistaking "Professional Circles" with a hobby device (NanoVNA), where my stated
usage was testing filter equipment below 50Mhz that comes with SO-239 connectors.
YES, there are some people that actually wish to test and align something
BELOW microwave frequencies. You did not offer an answer to the question;
How would you calibrate and hook up to a 14 Mhz bandpass filter that comes with
SO-239 connectors, to test and align it, using the NanoVNA? If you use a cal standard
set that is not the PL-259 / SO-239, then your reference plane will be meaningless at the actual
input to the filter. But the question becomes, at that low a frequency, does it matter?
Or should I still build a nice crappy SO-239 SOLT cal standard set for the crappy
connector choice that the entire industry puts on ALL amateur HF radios, tuners, amplifiers,
meters, and misc switching equipment and antenna's [because at that freq. it probably does
not matter] ? :-)
Please don't confuse "Professional" with frequency of use. Some frequencies
have plenty of commerical equipment in 2020 shipping with SO-239, and some
with BNC, and some with SMA, and some with Type N.
You can't really tell me that at 14Mhz you will see ANY visible appreciable difference
in signal on the screen between a PL-259, BNC, or Type N or SMA. At that
frequency, inside the chassis, some vendors do not even use coax cable, they
just use a twisted pair of wires. :-)
Cheers,
Neal
|
Roger:
Thanks for that. It looks easy enough to get the same diemsions for all three (open, short, load).
I will try building a set of those.
Cheers,
Neal
|
Here's a possibility. Use a SMA male to N female short cable from the
NanoVNA. Use N type OSL. Use a N male to PL259 adapter to connect the short
cable to the filter. At the frequencies that you specified the adapter
would make very little difference.
*Clyde K. Spencer*
toggle quoted message
Show quoted text
On Mon, Feb 24, 2020 at 10:39 PM Neal Pollack <nealix@...> wrote: David:
You are mistaking "Professional Circles" with a hobby device (NanoVNA),
where my stated
usage was testing filter equipment below 50Mhz that comes with SO-239
connectors.
YES, there are some people that actually wish to test and align something
BELOW microwave frequencies. You did not offer an answer to the
question;
How would you calibrate and hook up to a 14 Mhz bandpass filter that comes
with
SO-239 connectors, to test and align it, using the NanoVNA? If you use
a cal standard
set that is not the PL-259 / SO-239, then your reference plane will be
meaningless at the actual
input to the filter. But the question becomes, at that low a frequency,
does it matter?
Or should I still build a nice crappy SO-239 SOLT cal standard set for the
crappy
connector choice that the entire industry puts on ALL amateur HF radios,
tuners, amplifiers,
meters, and misc switching equipment and antenna's [because at that freq.
it probably does
not matter] ? :-)
Please don't confuse "Professional" with frequency of use. Some
frequencies
have plenty of commerical equipment in 2020 shipping with SO-239, and some
with BNC, and some with SMA, and some with Type N.
You can't really tell me that at 14Mhz you will see ANY visible
appreciable difference
in signal on the screen between a PL-259, BNC, or Type N or SMA. At that
frequency, inside the chassis, some vendors do not even use coax cable,
they
just use a twisted pair of wires. :-)
Cheers,
Neal
|
Hi Neal. I agree and no issue. You can build a set of SOL using SO239 connectors to create the open, short, and load. They would be fashioned in the same manner as demonstrated in prior discussions based on SMA connectors. The center pin snipped to create the open, snipped ad shorted with a brass or copper shim plate and 50 ohm using a pair of 100 ohm 1/8 W short leaded MF res in //. Done.
I think the biggest challenge and requires some thought is the adapter... moving from the SMA CONNECTOR on the vna to a PL259.
Or are you going to launch with the SO239? in which case you are building PL259 standards?
Alan
|
Hi Neal,
I use the nanoVNA for the same things.
Sma-to-PL259 works just fine to tune the filters for passband, S21 (loss)? and S11 (swr).
The 50MHz and HF measurements this way are accurate enough.
73
Arie PA3A
Op 25-2-2020 om 01:13 schreef Neal Pollack:
toggle quoted message
Show quoted text
Hi:
I am going to build some HF bandpass filters, in the range 1Mhz to 54Mhz.
Since most standalone filters are fitted with SO-239 sockets, I would use
reasonable quality SMA to PL-259 male cables, and want an SO-239 calibration
socket set.
What are people using for this type of work on HF ham gear? At these low
frequencies, it seems like the amount of effort in the following document:
might be overkill? Have people found simpler (less work) methods to get
adequate results for tuning a bandpass filter at frequencies less than 50Mhz?
|
FWIW, I' probably use 239/259 to SMA/N adapters, and then use SMA/N cal standards.? At HF the length and reactance of the adapters won't have any noticeable effect, and the SMA/N cal standards are probably better than any you could make for UHF.
John
toggle quoted message
Show quoted text
On Feb 24, 2020, 10:39 PM, at 10:39 PM, Neal Pollack <nealix@...> wrote: David:
You are mistaking "Professional Circles" with a hobby device (NanoVNA),
where my stated
usage was testing filter equipment below 50Mhz that comes with SO-239
connectors.
YES, there are some people that actually wish to test and align
something
BELOW microwave frequencies. You did not offer an answer to the
question;
How would you calibrate and hook up to a 14 Mhz bandpass filter that
comes with
SO-239 connectors, to test and align it, using the NanoVNA? If you
use a cal standard
set that is not the PL-259 / SO-239, then your reference plane will be
meaningless at the actual
input to the filter. But the question becomes, at that low a
frequency, does it matter?
Or should I still build a nice crappy SO-239 SOLT cal standard set for
the crappy
connector choice that the entire industry puts on ALL amateur HF
radios, tuners, amplifiers,
meters, and misc switching equipment and antenna's [because at that
freq. it probably does
not matter] ? :-)
Please don't confuse "Professional" with frequency of use. Some
frequencies
have plenty of commerical equipment in 2020 shipping with SO-239, and
some
with BNC, and some with SMA, and some with Type N.
You can't really tell me that at 14Mhz you will see ANY visible
appreciable difference
in signal on the screen between a PL-259, BNC, or Type N or SMA. At
that
frequency, inside the chassis, some vendors do not even use coax cable,
they
just use a twisted pair of wires. :-)
Cheers,
Neal
|
There is no such thing as a PL259/SO239 standard as these connectors are not matched. It doesn't matter so much at HF but they are awful things. Why manufacturers still use them beats me but they do and even on expensive equipment. I suppose it inertia.
Anyway, the best way to solve your problem is to either avoid it, but calibrating at N or SMA and using adaptors, or just do the best you can. I assume you want to interface to a SO239 so get one and leave it open, get another and short it out and get a third with a good 50 ohm load. Also get a through barrel. You should then be able to calibrate well enough to test a filter. The leads from the VNA should be SMA one end and PL259 the other. You can use adaptors as these will be calibrated out but best avoided if you can.
Mike
|
Sorry to have offended you, but the facts are that the 239/259 are not good
connectors as they are not impedance controlled. I can account for at
least four dielectric types used in these connectors with no adjustment in
the geometry to compensate for differing ¦År. By professional, I refer to
those of us who do or have done professional RF design and testing work as
part of or totally as a career. Yes, the 239/259 is 'standard' in the
amateur and CB world at HF frequencies, but you will seldom see them used
in critical applications (NASA, Uncle, commercial comm...). After all,
even Collins Radio used RCA jacks/plugs in their transmitters and
receivers. They are even worse.
But, does it matter?. Likely not at HF through, maybe, 2-meters. I have
measured an increase of a bit over 1 dB in noise figure at 144.200 MHz
totally due to two SO-239 connectors. Does it matter for FM operation?
No. Does it matter for weak signal and EME? Absolutely yes. Both
239/259's and the RCA connectors present such a small portion of a
wavelength at HF that they likely don't matter. When they become a
significant portion of a wavelength (maybe > 0.10 wavelengths - corrected
for the dielectric) then they become a potential problem.
What do I do to test a network with 239/259 connectors? I have an
extensive collection of adaptors which I install to interface with my
cables and test equipment. When tested/evaluated, the 239/259's become
part of the network. The equipment is calibrated usually with either BNC,
N, or SMA, whichever interfaces with the adaptors I choose to use. If I
really care about the results, I do not even use BNC above 400 MHz.
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Feb 25, 2020 at 3:39 AM Neal Pollack <nealix@...> wrote: David:
You are mistaking "Professional Circles" with a hobby device (NanoVNA),
where my stated
usage was testing filter equipment below 50Mhz that comes with SO-239
connectors.
YES, there are some people that actually wish to test and align something
BELOW microwave frequencies. You did not offer an answer to the
question;
How would you calibrate and hook up to a 14 Mhz bandpass filter that comes
with
SO-239 connectors, to test and align it, using the NanoVNA? If you use
a cal standard
set that is not the PL-259 / SO-239, then your reference plane will be
meaningless at the actual
input to the filter. But the question becomes, at that low a frequency,
does it matter?
Or should I still build a nice crappy SO-239 SOLT cal standard set for the
crappy
connector choice that the entire industry puts on ALL amateur HF radios,
tuners, amplifiers,
meters, and misc switching equipment and antenna's [because at that freq.
it probably does
not matter] ? :-)
Please don't confuse "Professional" with frequency of use. Some
frequencies
have plenty of commerical equipment in 2020 shipping with SO-239, and some
with BNC, and some with SMA, and some with Type N.
You can't really tell me that at 14Mhz you will see ANY visible
appreciable difference
in signal on the screen between a PL-259, BNC, or Type N or SMA. At that
frequency, inside the chassis, some vendors do not even use coax cable,
they
just use a twisted pair of wires. :-)
Cheers,
Neal
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
|
On Tue, Feb 25, 2020 at 10:55 AM, David Eckhardt wrote:
After all,
even Collins Radio used RCA jacks/plugs in their transmitters and
receivers. They are even worse.
Hi Dave. No they are not. The RCA connectors were extensively used at UHF, 400- to- 520 MHz as in/out 50 ohm connectors on helical filters. They work excellent and the unloaded Q and insertion loss of these mobile filters is excellent even by today's standards. Alan
|
Yes, I've modified a few for use on our 220 band. But, they are high
quality RCA connectors, not the RS (RIP) variety.
Dave
toggle quoted message
Show quoted text
On Tue, Feb 25, 2020 at 8:07 PM alan victor <avictor73@...> wrote: On Tue, Feb 25, 2020 at 10:55 AM, David Eckhardt wrote:
After all,
even Collins Radio used RCA jacks/plugs in their transmitters and
receivers. They are even worse.
Hi Dave. No they are not. The RCA connectors were extensively used at UHF,
400- to- 520 MHz as in/out 50 ohm connectors on helical filters. They work
excellent and the unloaded Q and insertion loss of these mobile filters is
excellent even by today's standards.
Alan
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
|
I agree... they are not "phono" connectors. But let us qualify all this. Just for giggles and grins I got out the junk box of filters I have designed and built over the years and here is one of those UGLY ones!
This is a 6 pole 500 MHz helical filter equipped with those ugly RCA connectors. Now adding insult to injury to get to the NICE SMA connector from RCA with NO ADAPTER REMOVAL routine applied... just using the vna saver routine did a cal out to the ends of a SMA-SMA cable. Then launched into the filter with SMA-to-BNC adapter and then from BNC-to-RCA adapter. All at 500 MHz. Geeeeeezzz... ya can't get much crappier than that! PIX attached and loss and match attached. The loss and match is awfully close to prior filters which launched to special probe card when the filter was first designed. Is it spot on? No. The adapter losses and their affect in SWR are clearly present and at the end of the day, NO adapter unless it can be properly modeled and via arithmetic removed, is undesired.
Summary, all of this stuff has to be properly qualified and you have some idea of what to expect. Otherwise your never sure is it a measurement problem or a design over site.
|
I remember reading somewhere, back around the time I got my first ham license (1976), that somebody had swept an RCA connector and found it adequate up to 4 GHz.? It was NOT like the ones we used to buy at Radio Shack, but one like that on the adapter at the left side of the photo you posted.? Update: found a picture, attached.? Fender used to use these in their guitar amplifiers on the cables that connected to the reverb tank, and old floor-standing wood cabinet radio/phono combinations used them on the cable from the phono to the amplifier.? (Wish I still had one of those old radio/phonos. Some even had shortwave!)? As you can see in the attached photo, if you need some, you can get them at mojotone.com.? In small quantities, 48 cents.
toggle quoted message
Show quoted text
On 2/25/20 1:24 PM, alan victor wrote: I agree... they are not "phono" connectors. But let us qualify all this. Just for giggles and grins I got out the junk box of filters I have designed and built over the years and here is one of those UGLY ones!
This is a 6 pole 500 MHz helical filter equipped with those ugly RCA connectors. Now adding insult to injury to get to the NICE SMA connector from RCA with NO ADAPTER REMOVAL routine applied... just using the vna saver routine did a cal out to the ends of a SMA-SMA cable. Then launched into the filter with SMA-to-BNC adapter and then from BNC-to-RCA adapter. All at 500 MHz. Geeeeeezzz... ya can't get much crappier than that! PIX attached and loss and match attached. The loss and match is awfully close to prior filters which launched to special probe card when the filter was first designed. Is it spot on? No. The adapter losses and their affect in SWR are clearly present and at the end of the day, NO adapter unless it can be properly modeled and via arithmetic removed, is undesired.
Summary, all of this stuff has to be properly qualified and you have some idea of what to expect. Otherwise your never sure is it a measurement problem or a design over site.
|
This style of RCA was used by Yaesu (and probably others) on "interconnect" cables in their rigs in the late '70s early '80s. On Wed, 26 Feb 2020 at 00:25, Jim Allyn - N7JA <jim@...> wrote: I remember reading somewhere, back around the time I got my first ham
license (1976), that somebody had swept an RCA connector and found it
adequate up to 4 GHz. It was NOT like the ones we used to buy at Radio
Shack, but one like that on the adapter at the left side of the photo
you posted. Update: found a picture, attached. Fender used to use
these in their guitar amplifiers on the cables that connected to the
reverb tank, and old floor-standing wood cabinet radio/phono
combinations used them on the cable from the phono to the amplifier.
(Wish I still had one of those old radio/phonos. Some even had
shortwave!) As you can see in the attached photo, if you need some, you
can get them at mojotone.com. In small quantities, 48 cents.
|
David Eckhardt:
Thanks. I like your second reply. Indeed, I also work in Aerospace, and we use SMA connectors that are $100 each,
with VNA's costing more than $250,000. But again, my question was what type of hookup and cal do you guys use
for Ham Radio HF stuff with PL-259's, and you provided an answer this time. It seems like the consensus of this
thread is to use SMA male (NanoVNA) to PL-259 Male (BandPass filter side) jumper cables, and make some SO-239
Open, Short, Load (precision 100 ohm x 2 in parallel), so I can calibrate at the end of the adapter cable, then hook up
the filter. Again, you guys seem to confirm my earlier question; At less than 50 Mhz, the small length or connector
variation will likely not be visible enough to interfere with aligning a bandpass filter.
I like the youtube video that Roger posted about making a simple set of SO-239 SOL cal units.
And yes, at 2meters, I would expect it to start showing up. Most Europe 2m ham gear uses Type N connectors,
while USA ham gear at 2m still uses the SO-239. Rather silly using an SO-239 above 50Mhz. But how do we
change all that commercial and installed base inertia? Personally, I make professional looking type N jumper
cables all the time, using proper crimp or compression fittings. But most hams panic at the meer mention
of a type N connector. Comical or sad...
[Disclaimer: For SMA at home, I purchase aerospace surplus at the monthly swapmeet, where the high quality
jumper cables, adapters, 90 degree, splitters, couplers, and even precision 18Ghz loads, cost approx $1 to $5
instead of $100 and up. At those prices, I don't bother trying to make my own SMA jumper cables.]
And no, you did not offend me, but I slipped and let some personality/opinion show through :-)
Thanks for the help.
Cheers,
Neal
|
Yet another option, since the concept of even hobby cal standard for SO/PL connector is fuzzy at best, you can build your filter with SMA connectors, calibrate the VNA the usual way and when you are happy with the results, replace the SMA with SO. You will not be farther off than any other solution proposed here (which would all work equally well).
--
Didier Juges
KO4BB.com
|
RE comments on the PL259 and friends...
For HF a reasonable if not imperfect connector. Their biggest issue us the great
amount of variation in assembly and vendor. Best solution s make your own
or use a PL259 to SMA adaptor.
RCA connector, good for RF by the caveat us old timers know was they
are not suitable for high vibration and tend to be more than a little insecure.
Again they varied by vendor some decent most terrible.
As to 6m and up many radio come with SO239 or some version of that.
Not a preferred connector but at 6M ok. for 2M and up BNC or N.
I'm likely one of the few that will change out that connector for N or BNC
as there are similar mounting style version available for the same hole.
SO with that likely the only ones that have seen a MFJ259B with
type N connector know me. I found after making that change and
doing a full calibration it improved the instrument above 50mhz.
That and it made it far harder to borrow and use without permission.
The adaptor from N-female to SO239 is the permission.
Allison
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO
|
It's interesting how the focus or center of discussions drifts. This started about testing filters with UHF connectors, so obviously they would have to be used in this case.. The discussion of N connectors has happened often, and in fact I'd read some time ago that, as well as 'inertia', one strong reason for using UHF connectors on ham gear was power handling. Someone in that discussion said that N connectors wouldn't handle ( or maybe just wouldn't be reliable) for high-power ham rigs. The main reason given was the small center pin of the N connector. (I suppose if that's the case, BNC's might have the same problem.)
It would be good to know how much improvement was gained by the folks who have changed their HF station connectors from UHF to the N series, both in transmitting and in reception measurements.
Somewhat related to this (but not the NanoVNA) has anyone researched the development of the UHF (SO-239/PL-259) series and what it's original purpose might have been?
Doug, K8RFT
|
Neal AB6G
Roger Need
Arie Kleingeld PA3A
Jim Allyn - N7JA
