Re: Help reading Antenna plots
EDIT
I got 100ft of RG8X coax today and a gas tube lightning arrest delivered today.
I have added some more plots after doing some testing.
First i plotted after just replacing the coax going from that 50ft amazon stuff with my connectors to 100 feet of RG8X with factory connectors
I then moved the antenna diagonally in my yard and stretched out the gypsy equally on each side. There is exactly 21 1/4 inches of wire out
past the 7Mhz silver marker on the wire on each side of the antenna. Its still only 6 feed off the ground though.
SInce I had a ton of extra coax in the garage and i was at this point just playing with the nanoVNA i measured aproximately 19 feet of coax
and wound it tight around a cardboard tube i had in the garage that was 2 5/8 inch diameter and took another scan which didn't show any
change really.
Not sure if i should leave this RF Choke on it as i will be transmitting and I don't know what effects it will have maybe someone could shed insight into why
i should remove or keep it on there.
The last scan is the entire setup from 30Khz to 1.2Ghz
The antenna is running pretty well right on the line of North to South in my location
First Impressions with the Kenwood TS-440 i had a 59+10 wefax signal at 6338.60 that was amazing
A quick scan AM Broadcast is not that good so i don't think the low end gonna be very useful.
A quick scan at 9Mhz up gave me at least 7 am stations i have never heard before all at 59+10 or more although some faded out as it got darker. I station i identified was WRMI at 9.955.00. Anywhere around 7Mhz had lots of chatter on side band.
The kenwood has a tuner so if anyone can give me any insight from the plots where i may not want to try and tune or transmit would be great. I am really interested in all of the data modes that are out there. Flurries and high winds here so hopefully i get a nice day in the future to get it higher in the air.
|
My friend N8CDWCarl
Has a few month old h4 new in the box with the gold lettering unopened never used I think he's looking to sell it I don't know how much he wanted
I contacted him for info so I may post it into the group if he comes back with a price.
He lives in Rockford, IL
--
Sent from my Android phone with GMX Mail. Please excuse my brevity.
toggle quoted message
Show quoted text
On 11/2/20, 16:52 "Roger Need via groups.io" <sailtamarack@...> wrote:
I don't think anyone has made a copy of Hugen's H4 (in the plastic case)
that is shipped in a gift box with gold lettering. You can find resellers
that buy from Hugen in bulk and then sell them on Amazon. They charge more
that Hugen or R and L but returns are easy with Amazon if something is not
to your satisfaction.
Roger
|
Order directly from Hugen?
toggle quoted message
Show quoted text
On Tue, 3 Nov 2020 at 00:35, DK <donaldphilbin@...> wrote: Gang,
Can someone please supply a link to a reputable supplier for a - H4? Is it
important to specifically get the specific Hugen model.
Thank you in advance.
D.K. KD6TK
|
I don't think anyone has made a copy of Hugen's H4 (in the plastic case) that is shipped in a gift box with gold lettering. You can find resellers that buy from Hugen in bulk and then sell them on Amazon. They charge more that Hugen or R and L but returns are easy with Amazon if something is not to your satisfaction.
Roger
|
I bought my NanoVna SAA2N
From R & L
Used them a few times w/o any issues
Ed WB9RAA.
--
Sent from my Android phone with GMX Mail. Please excuse my brevity.
toggle quoted message
Show quoted text
On 11/2/20, 16:35 DK <donaldphilbin@...> wrote:
Gang,
Can someone please supply a link to a reputable supplier for a - H4? Is it
important to specifically get the specific Hugen model.
Thank you in advance.
D.K. KD6TK
|
R and L stocks it but are currently out of stock.other than them I don¡¯t know of any us suppliers. On Mon, Nov 2, 2020 at 5:35 PM DK <donaldphilbin@...> wrote: Gang,
Can someone please supply a link to a reputable supplier for a - H4? Is it
important to specifically get the specific Hugen model.
Thank you in advance.
D.K. KD6TK
-- 73, Tripp Sanders K5TRP
|
Gang,
Can someone please supply a link to a reputable supplier for a - H4? Is it important to specifically get the specific Hugen model.
Thank you in advance.
D.K. KD6TK
|
Re: 75 ohm cable to match 50 ohm to 300 ohm folded dipole
*FREE online resources for modeling and analysis:*
SimSmith:
SimSmith Tutorial:
EZNEC: (Some limitation
with the free version)
4NEC2: (My
favorite - many hooks and options, more powerful than EZNEC)
KIND WARNING: Don't jump directly into 4NEC2 unless you are well versed in
antenna modeling and design. Learn to deal with EZNEC before tackling
4NEC2.
Dave - W?LEV
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 7:23 PM <ac7lx@...> wrote: You should note his comment about using it as the driven element in a
Yagi. When one adds parasitic elements (i.e. yagi), the feed-point
impedance will change in accordance with said parasitic elements and
spacing. As another responder posted, this can be seen in antenna
simulations.
Case in point, the proverbial direct fed yagi found all over the internet.
The driven element, while basically a dipole (75 ohm impedance), by adding
a director and reflector with the correct spacing, the feed-point impedance
drops to ~50 ohms.
Somewhat related to this topic, you might want to look into twelfth-wave
matching using sections of feedline of different impedances to convert from
one Z to another.
As yet another responded mentioned, SimSmith (highly recommended & free),
lets you examine many scenarios and will perhaps, provide some deeper
insight into impedance.
:)
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Re: RF from outside - Did I brick my nanoVNA-H?
On 11/2/20 12:44 PM, Larry Rothman wrote: Yeah, port 0 I believe can push about 12dbm when the osc is set to 8mA (per an earlier post this year) so as Jim stated, the inputs should be capable of quite a bit more than that.
However, with that said, it is always wise to use an attenuator(s) on the ports.
I can remember one of the engineers I worked with figured they could measure 5W with an HP power sensor without using any attenuators. His manager was not too happy about getting the sensor repaired for $$$
One of those 'life lessons'.....
Oooh, D-series sensors like the HP8487D power sensor for all manner of power meters over the years. - 100 pW to 10 microwatt (-70 to -20 dBm). Leave that precision 50 dB pad on unless you're really sure. 100mW average or peak is the max. you know it's special when there's multiple App Notes about it.. 7 Practices to Prevent Damaging Power Meter Power Sensors Power Sensor Electrical Overstress (EOS) Failure Verification Guideline (this one is cool... using a VNA to figure out if you damaged it, by TDR) And pictures of broken units, too!
|
Re: RF from outside - Did I brick my nanoVNA-H?
And then there was the engineer (?) who changed the (Signal Generator)-(Switchable Attenuator)-(Amplifier)-(Antenna) setup to:
(Signal Generator)-(Amplifier)-(Switchable Attenuator)-(Antenna) and tried (and fried) all positions of the switchable attenuator when the output was too low.
--John Gord
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 12:44 PM, Larry Rothman wrote:
Yeah, port 0 I believe can push about 12dbm when the osc is set to 8mA (per an
earlier post this year) so as Jim stated, the inputs should be capable of
quite a bit more than that.
However, with that said, it is always wise to use an attenuator(s) on the
ports.
I can remember one of the engineers I worked with figured they could measure
5W with an HP power sensor without using any attenuators. His manager was not
too happy about getting the sensor repaired for $$$
One of those 'life lessons'.....
On Mon, Nov 2, 2020 at 03:33 PM, John Gord wrote:
Leif,
Given the resistive networks between the connectors and the active devices,
I
suspect 10mW is very conservative.
--John Gord
On Mon, Nov 2, 2020 at 12:10 PM, Leif M wrote:
Do they really burn out at around 10mW, That is not much. I plan to play
with
an amplifier putting out more than that. I'll use an attenuator so mine is
safe but accidents happen.
|
Re: RF from outside - Did I brick my nanoVNA-H?
Yeah, port 0 I believe can push about 12dbm when the osc is set to 8mA (per an earlier post this year) so as Jim stated, the inputs should be capable of quite a bit more than that.
However, with that said, it is always wise to use an attenuator(s) on the ports.
I can remember one of the engineers I worked with figured they could measure 5W with an HP power sensor without using any attenuators. His manager was not too happy about getting the sensor repaired for $$$
One of those 'life lessons'.....
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 03:33 PM, John Gord wrote:
Leif,
Given the resistive networks between the connectors and the active devices, I
suspect 10mW is very conservative.
--John Gord
On Mon, Nov 2, 2020 at 12:10 PM, Leif M wrote:
Do they really burn out at around 10mW, That is not much. I plan to play
with
an amplifier putting out more than that. I'll use an attenuator so mine is
safe but accidents happen.
|
Random Learning Experiences with Nano-VNA
I haven't posted too much to the group, but I've been reading every post with great interest.
I've had my NanoVNA-H4 for a couple of months now, and to be totally honest, I have done absolutely nothing with it that anyone would call "working" or "productive"...at least in the sense of using the gizmo to actually accomplish some specific task.
Instead, I've been "playing". And yes, my wife does call the device "...your new toy..."
For example, today I disconnected my 6m J-Pole from the FM transceiver, connected the antenna to my NanoVNA, and did some sweeps in the 6m band. Interesting to see where the antenna has various lows and highs.
Then, as I leaned back in my chair to think, I saw my 6m "tuner" (God I hate that term!) sitting on the shelf doing nothing beyond gathering dust.
I grabbed a patch cord and put the tuner (!!) between the antenna and the NanoVNA. With the tuner in BYPASS mode, I had pretty much the same Smith chart as before adding the tuner into the mix. Then I switched to TUNE mode...the trace went crazy! After playing with the controls a little, I was first able to get back to a trace very similar to the earlier output. Only slight movements of the controls produced huge changes, however.
I sat there for more than an hour just going back and forth on the tuner controls while watching the NanoVNA traces, and I found a spot that seemed to be the "butter zone"...using SWR simply because the numbers are easier, at 52MHz the system was at 1.05. At 50MHz there was 1.30 and at 54MHz I had 1.35. With the so-called tuner out of the line, the SWR at the low band edge is 1.95, 1.40 at the center, and 2.00 at the top end.
In other words, really, the tuner is useless for the local FM work I use the J-Pole for.
But...
I gained some insight on just how my home brew antenna handles frequency changes. I learned that the "tuner" will make the transmitter happy if the need arises, albeit the adjustment is very touchy. And I picked up some additional practice with the NanoVNA...like I found I can now do the calibration procedure from memory and very quickly.
I see this as a learning experience for me.
And I'm loving every minute of it!
Many thanks to those who post here often. You may not know it, but I am picking your brain through your messages.
Take Care & 73
de KC6UFM
Charles
|
Re: RF from outside - Did I brick my nanoVNA-H?
Leif,
Given the resistive networks between the connectors and the active devices, I suspect 10mW is very conservative.
--John Gord
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 12:10 PM, Leif M wrote:
Do they really burn out at around 10mW, That is not much. I plan to play with
an amplifier putting out more than that. I'll use an attenuator so mine is
safe but accidents happen.
|
Re: RF from outside - Did I brick my nanoVNA-H?
On 11/2/20 12:10 PM, Leif M wrote: Do they really burn out at around 10mW, That is not much. I plan to play with an amplifier putting out more than that. I'll use an attenuator so mine is safe but accidents happen.
well, the input circuit for port 2 has a 56 ohm resistor across it (part of a 50 ohm input attenuator) - It's a fairly small chip, but it can probably take 50 mW without too much trouble for a short time. (0402 = 62 mW, 0603 = 100mW, 0805=125 mW) (see ) Put 10 W into it, and the resistor probably vanishes. The attenuator is about 20 dB (10:1 voltage ratio) The input to the mixer would be the next thing, but you'd have to swing past the supply a fair amount, which would be about 1.75V rms.. So blowing up the mixer would be 17V input.. the resistor will die first If you put reverse power into Port 1, the same sort of analysis applies, you've got the resistor bridge, and ultimately the Si53541 output. Again, probably one of those "don't swing past the supplies". There's about 50 ohms to ground, spread across multiple resistors.
|
Re: RF from outside - Did I brick my nanoVNA-H?
Do they really burn out at around 10mW, That is not much. I plan to play with an amplifier putting out more than that. I'll use an attenuator so mine is safe but accidents happen.
|
Bruce,
Check out this groups wiki for a discussion and review of the various NanoVNA products. The -H4 has many advantages besides the 4" screen.
From memory...
- Bigger battery
- Better RF front end design and power supply so less noise and better S21 performance
Firmware released by Hugen for the -H and -H4 is a bit long in the tooth now. Another firmware developer DiSlord has made extensive changes to the code for the -H4 to increase the number of data points, more dynamic range, nicer user interface and power output adjustments. For those that want to do hardware mods there is now support for an SD card to store measurements and a date clock. I believe he has also pushed the maximum frequency higher
Personally I wouldn't even consider a -H 2.8" or one of the clones. For $10 more than a -H you get a lot more for your money. If you want a metal case NanoVNA with a 4" screen the NanoVNA-F is another option.
You might want to look at one of the newer V2 4" designs like an S-A-A-2 with N connectors or a V2 Plus 4.
Maybe Herb Walker can add some comments as he is much more familiar with the latest generation products than me.
Rogerr
|
Re: 75 ohm cable to match 50 ohm to 300 ohm folded dipole
You should note his comment about using it as the driven element in a Yagi. When one adds parasitic elements (i.e. yagi), the feed-point impedance will change in accordance with said parasitic elements and spacing. As another responder posted, this can be seen in antenna simulations.
Case in point, the proverbial direct fed yagi found all over the internet. The driven element, while basically a dipole (75 ohm impedance), by adding a director and reflector with the correct spacing, the feed-point impedance drops to ~50 ohms.
Somewhat related to this topic, you might want to look into twelfth-wave matching using sections of feedline of different impedances to convert from one Z to another.
As yet another responded mentioned, SimSmith (highly recommended & free), lets you examine many scenarios and will perhaps, provide some deeper insight into impedance.
:)
|
Hello,
If you look at the PCB there are solder pads where you can either use the 49.9 Ohm resistors to build a 50 Ohm load on one section and use the other to build another load with larger resistors or you can build either one or two attenuators. You have to supply the resistors for a second load or attenuators.
The reason the pads are larger on one end is to allow you to use larger watage resistors.
If you looked at the board before you built it you will see the pads for the jacks they are layed out in a specific pattern. They are not a regular grid pattern.
If you do a Google surch for the test board you will find the actual pattern and layouts and for assembling the attenuators.
Clyde Lambert KC7BJE
|
Re: Help reading Antenna plots
Thank you, HexandFlex. I should have had less Tequila when I wrote that. Loss on the Smith Chart is indicated as hugging the center of the chart. Low loss but bad match overall would write the outside of the chart. My error. That's for the correction. Dave - W?LEV On Mon, Nov 2, 2020 at 6:12 AM HexAndFlex via groups.io <iain_haggis= [email protected]> wrote: Get yourself an antenna tuning unit (ATU). If doing receive only you will
need a manual type as the automatic ones need a few watts of tx power to
detect a bad match.
You can use the VNA to help tune to a particular frequency. The closer the
original match is to the outside of the Smith chart the harder it is to
match and the narrower any tuning will be.
Btw, hugging the outside of the Smith chart does NOT indicate loss. It
indicates reflection. Loss tends to make the match look better than it
really is.
-- *Dave - W?LEV* *Just Let Darwin Work*
|
Re: 75 ohm cable to match 50 ohm to 300 ohm folded dipole
Measure the antenna (or model it), import the file into SimSmith
and try to match it by using the coax models.
toggle quoted message
Show quoted text
On Mon, 2 Nov 2020 at 14:32, AllassoPraise <allassopraise@...> wrote: I saw in this video the other day at 1:40:
The presenter talks about using a length of 75 ohm cable inline to
match a (theoretically) 300 ohm folded dipole to (presumably) 50
ohms. Has anyone else ever heard of doing that?
It sounds like it might be easier than using the 1/2 wave phasing coax
balun method, especially at 1 to 2 GHz frequencies, where tweaking the
antenna can require a lot of adjustments to the 3" to 6" coax loop.
|
Roger Need
Clyde Lambert