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On 9/21/21 10:17 AM, Jim Lux wrote:

On 9/21/21 9:57 AM, kk7xo via groups.io wrote:

I have a ratchet crimp connector and can install various types of terminations.? But what tool(s) do the pros use to strip coax?? Any suggestions?

One of those multiblade spin around the coax

I've used a Paladin CST for decades.

I tried to find some catalog info, but you need to dig through distributors pages..

There's different flavors of these things. 2 and 3 level stripping, adjustable or not, whether are not you handle just one size of coax or multiples, etc.

The 2 level, fixed size coax ones are cheapest ($20-30), the fancy ones have cassettes that you can swap in if you regularly use multiple sizes of coax.

Check your cal loads with an ohm meter to see if they are OK at DC.
Take a look at the inside socket of the SMA connectors. Perhaps "drilled out" by rotating pin after too may uses.

Roger

Dick,

Does the article indicate how much "blow-by" you get (due to the mechanical switches in this design) as the frequency increases?

Roger

On 9/21/21 9:57 AM, kk7xo via groups.io wrote:

I have a ratchet crimp connector and can install various types of terminations. But what tool(s) do the pros use to strip coax? Any suggestions?

One of those multiblade spin around the coax

I've used a Paladin CST for decades.

I have a ratchet crimp connector and can install various types of terminations. But what tool(s) do the pros use to strip coax? Any suggestions?

I have ordered a limited batch of boards from JLCPCB for the QEX September/October 2021 “Miniature SMA Step Attenuator” pp 9-21 by Tom Alldred VA7TA.

If you are interested in a board, at $3.00 ppd CONUS, please reply off line [click the “Private” button].
I expect to receive the boards in the first week of October and will have 8 spare boards available.
If there is sufficient additional interest, I would be willing to make a second order.

See attached for some additional info.

Dick K9IVB

On 21/09/2021 13:45, Karl Jan Skontorp wrote:

Hi all!
Is there anyone who can be so kind as to give me some help to make my device work again or at least tell me what has happened to my device?
I have a NanoVNA V2_2 - SAA-2N with the DiSlord firmware, version 1.0.69 - build time: Jul 31 2021 - 12:27:19.
The device has been working without problems for a long time, last time was yesterday or the day before. When I turned the device on today, I got a "strange" screen. I have always had a small point at the right in the smith-chart when input is open, a small point in the middle with 50ohm connected and a small point at the left, when shorted. Today I got something else! Please have a look at the pictures below. The open point is "big", 50ohm is smaller and short is still a small point. If I do a measurement, I get the correct "form", but the curve is not as "clear" line as I had earlier? I tried to load an older firmware, but the result is the same. I think there is a hardware error...
I will be very grateful for all the advice and views to solve the problem!
Karl Jan - LA3FY

Karl,

Cab you still calibrate the device. I wonder whether the calibration has been lost?

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

On 9/21/2021 8:39 AM, K8HTB wrote:

One thing I have found is when tightening the pl259 you have to make sure the nubs are well seated in the so239 no air gaps.

Good point.

But, people should keep in mind that PL259 and N style connectors are two different animals. The outer shell of a PL259 is part of the Rf connection, but the outer shell of an N connector is just a mechanical connection. The RF connection of the N connector is internal to the outer shell and it is possible to over-tighten and N connector. Finger snug for an N connector is good.

73, Joe, K1ike

Hi all!
Is there anyone who can be so kind as to give me some help to make my device work again or at least tell me what has happened to my device?
I have a NanoVNA V2_2 - SAA-2N with the DiSlord firmware, version 1.0.69 - build time: Jul 31 2021 - 12:27:19.
The device has been working without problems for a long time, last time was yesterday or the day before. When I turned the device on today, I got a "strange" screen. I have always had a small point at the right in the smith-chart when input is open, a small point in the middle with 50ohm connected and a small point at the left, when shorted. Today I got something else! Please have a look at the pictures below. The open point is "big", 50ohm is smaller and short is still a small point. If I do a measurement, I get the correct "form", but the curve is not as "clear" line as I had earlier? I tried to load an older firmware, but the result is the same. I think there is a hardware error...
I will be very grateful for all the advice and views to solve the problem!

Karl Jan - LA3FY

One thing I have found is when tightening the pl259 you have to make sure the nubs are well seated in the so239 no air gaps.

Unfortunately it is easy to just screw the connection together and not realize the they are not together internally and I am sure that makes for a bad connection.

I push them together with the outer shell backed out and and try to rotate the inner if it turns it isn't hitting the nubs and is not seated.

Also I have used pliers tighten at times.

De K8HTB Joe

Even more interesting is to do a wide/multt-band sweep with the nanoVNA: You can easily see the effects of frequency on feedline losses in the loss.

I usually do a 1-30MHz sweep of my multiiband-HF antennas at both the feedpoint, and at the exciter (including any switches, transmatches, patch cables, etc).

-Mat, N8TW

On Sunday 19 September 2021 02:20:24 pm Roger Need via groups.io wrote:

On Sun, Sep 19, 2021 at 11:05 AM, <kk7xo@...> wrote:

By the way, that J-Pole article Jim posted is great. I'd like to link to it
from my article. Is it available online? Like maybe the ARRL site?

Albert KK7XO

Here you go >>>

Roger

Better, the pdf didn't include the figures...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

Howdy Albert,
You can get SMA connectors for RG-8X (and -59, any .242" coax), tho you do of course need the ratchet crimper with the appropriate dies.. I got both on amazon a while back.
PL-259s are not that bad; the modern ones with Teflon are supposedly considerably better than the old phenolic ones. And the impedance bump is a small fraction of the wavelength at 2M.
Consider that most 2 meter mobile antennas are using 15-18 feet of RG-58 and a PL-259...
Also, consider that final tuning of the antenna is measured at the radio end of the coax; the object being to get 50 ohms at the radio.
73, --kv5r

Since the antenna is SMA, would it make sense to put BNC connectors on the RG-8x and use a BNC->SMA adapter? Then not only do you avoid the PL-259 entirely, but you can easily calibrate at the SMA.

If you have the strip and crimp tools, BNC crimp for RG-8x is easy, but even if you don't, BNC solder/clamp for RG-8x isn't rocket science.

73, Willie N1JBJ

If you calibrate at the end of the cable, there should be no difference in either case.
But I would choose option 1 because the attenuation of 18 feet of LMR-100 at 145MHz is only 1.62 dB and the performance of this cable will be normal. The performance of PL-259 connectors is difficult to predict. They usually have a lower impedance than 50 Ohms. I have such a PL259/SO239 connector set that has 25 Ohms. This increases the SWR to 1.3 on 145MHz and on 433 to 2.3.
I did an experiment once, I compared the results of antenna measurements on 433 connected directly, and using this bad PL259/SO239 25 Ohm set calibrating before the set and after the set. The calibration compensated for the error interjected by those connectors and the results were almost identical.
Green - direct connected antenna
Red - Antenna connected through wrong PL259/SO239 adapter set
Blue - Antenna connected through wrong PL259/SO239 adapter set, but calibrated after adapter set.

On Sun, Sep 19, 2021 at 11:33 AM, <kk7xo@...> wrote:

I have two pieces of coax I can use.

It's a bit late now for this reply, but here goes -

Do it with both cables, and compare the results.
Then you could share the results, too! I think it would be an interesting comparison.

--
Doug, K8RFT

The article by N3GO states
"I ran a quick ELNEC [3] simulation of an end-fed vertical dipole to assess what feedpoint impedance it predicted. I varied the wire size and height above ground to observe the changes, and the results appeared to vary slightly around 7000 ohms. "
I measured 6.12K – j2.54K which is close to his results.

The ZIP file also contains the HTML article and the figures that go along with it. Open JPOLE.HTM with your browser and you will see the article with the referenced figures.

73

-Jim
NU0C

On Sun, 19 Sep 2021 16:41:15 -0700
"Roger Need via groups.io" <sailtamarack@...> wrote:

On Sun, Sep 19, 2021 at 02:26 PM, Jim Shorney wrote:

I found a link to the full content of the article:

That appears to be just a link to a zip file containing the calculation programs. No article there from what I can see.

Roger

On Sun, Sep 19, 2021 at 02:26 PM, Jim Shorney wrote:

I found a link to the full content of the article:

That appears to be just a link to a zip file containing the calculation programs. No article there from what I can see.

Roger

I found a link to the full content of the article:



N3GO renewed his license in 2019 so presumably he is still around.

73

-Jim
NU0C


On Sun, 19 Sep 2021 11:20:24 -0700
"Roger Need via groups.io" <sailtamarack@...> wrote:

On Sun, Sep 19, 2021 at 11:05 AM, <kk7xo@...> wrote:

By the way, that J-Pole article Jim posted is great. I'd like to link to it
from my article. Is it available online? Like maybe the ARRL site?

Albert KK7XO

Here you go >>>

Roger