Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Recommend best "null modem" cable for CAT?  (Read 3354 times)
KE2KB
Member

Posts: 633




Ignore
« on: October 30, 2017, 02:10:57 PM »

Hi;
I have a new Yaesu Ft-450D and I want to run CAT. Does anyone have a preferred brand of cable? I know I can build my own, but it hardly seems logical, considering I can buy one made in China for $5.
I would think I need good shielding and possibly ferrites to prevent RF from getting into my PC, or back into the radio. My station is less than 50ft from one leg of my 40m inverted vee. I am running only 100W max, and the antenna and feed are well matched. I haven't really had any problem with RF in the shack, but if I connect an audio cable from the rig's headphone jack to my PC, I do get some feedback. That cable is shielded (connected at each end to the chassis), but has no ferrites on it.

Thanks for your advice
Frank
Logged
NA4IT
Member

Posts: 42


WWW

Ignore
« Reply #1 on: October 31, 2017, 04:15:08 AM »

Quote
I would think I need good shielding and possibly ferrites to prevent RF from getting into my PC, or back into the radio.

There's your key. You said it. However, know if a cable is shielded enough is hard to discern, as you don't get to know what is inside the cable. But in my experience, clamp on ferrites on the cable should take care of any problems. But buy a quality cable. Thicker is usually a sign of better and shielded.

Also, you don't need a "null modem" cable. You need a "straight cable". It is different, and what the 450 calls for in the manual.
Logged
KE2KB
Member

Posts: 633




Ignore
« Reply #2 on: October 31, 2017, 11:10:02 AM »

Quote
I would think I need good shielding and possibly ferrites to prevent RF from getting into my PC, or back into the radio.

There's your key. You said it. However, know if a cable is shielded enough is hard to discern, as you don't get to know what is inside the cable. But in my experience, clamp on ferrites on the cable should take care of any problems. But buy a quality cable. Thicker is usually a sign of better and shielded.

Also, you don't need a "null modem" cable. You need a "straight cable". It is different, and what the 450 calls for in the manual.
Thanks for clarifying that. Someone said "null modem", and I understand that to mean that RXD and TXD are swapped at one end.
I haven't looked too closely at the 450D manual so far as CAT goes, but was planning to check it out before I buy any cable.

I have been reading a document entitled "RFI-Ham.pdf" which I downloaded, and it is saying that a tightly twisted pair may offer better RFI protection than a shielded - but not twisted - cable.
I could use a CAT5 patch cable, or I was thinking of buying a bulk spool of CAT6 - thinking that CAT6 would be a tighter twist than CAT5, but I'll have to do some more research into that.
Logged
AE5GT
Member

Posts: 33




Ignore
« Reply #3 on: October 31, 2017, 07:48:56 PM »

I would look for a cable that has clear insulation with a tightly woven  braid .
Same goes for any usb cables in the shack(usb is can be exceptionally noisy and will cause issues if the antenna is close by) ..I  use Rosewill RCW106s now but if your careful you can get some cheaper with ferrites on ebay.
Logged
NA4IT
Member

Posts: 42


WWW

Ignore
« Reply #4 on: November 01, 2017, 08:19:47 AM »

Quote
I have been reading a document entitled "RFI-Ham.pdf" which I downloaded, and it is saying that a tightly twisted pair may offer better RFI protection than a shielded - but not twisted - cable.
I could use a CAT5 patch cable, or I was thinking of buying a bulk spool of CAT6 - thinking that CAT6 would be a tighter twist than CAT5, but I'll have to do some more research into that.

I do agree with that statement, however I'm not too sure how well it works at HF frequencies. I myself have used it on VHF and UHF, and do have a short (8") piece in an adapter from RJ45 to 8 pin round mic connector on my FT-857D, and have noticed no problems on HF. I do also have a ferrite bead on it.
Logged
KE2KB
Member

Posts: 633




Ignore
« Reply #5 on: November 01, 2017, 03:32:09 PM »

Quote
I have been reading a document entitled "RFI-Ham.pdf" which I downloaded, and it is saying that a tightly twisted pair may offer better RFI protection than a shielded - but not twisted - cable.
I could use a CAT5 patch cable, or I was thinking of buying a bulk spool of CAT6 - thinking that CAT6 would be a tighter twist than CAT5, but I'll have to do some more research into that.

I do agree with that statement, however I'm not too sure how well it works at HF frequencies. I myself have used it on VHF and UHF, and do have a short (8") piece in an adapter from RJ45 to 8 pin round mic connector on my FT-857D, and have noticed no problems on HF. I do also have a ferrite bead on it.
Maybe I can get a cable that is "the best of both worlds"; well shielded twister pair
Logged
AA4PB
Member

Posts: 14332




Ignore
« Reply #6 on: November 01, 2017, 03:50:02 PM »

Twisted pair depends on having balanced input and output connections in order for the signal to be equal and opposite polarity on the two wires. If one of the wires is grounded (thus unbalanced), as it is in most RS-232 applications, then a twisted pair will be ineffective.

Logged

Bob  AA4PB
Garrisonville, VA
KE2KB
Member

Posts: 633




Ignore
« Reply #7 on: November 01, 2017, 05:10:00 PM »

I ordered 250ft of shielded Cat6e cable on Ebay. Whether or not I use this cable for my CAT cable remains to be seen. But the fact that this cable is twpr and has a shield, it should work. That said, I may still buy the RS233 cable. I intended to use the Cat6e cable to replace the old copper telephone wire in the house, and for LAN wiring.
Logged
KE2KB
Member

Posts: 633




Ignore
« Reply #8 on: November 01, 2017, 05:18:52 PM »

Forgot to look for my RS232 port. PC doesn't have one, but there is an IDC10 header on the mobo where a rear panel 9D would connect. I think I have the 9D connector, but I'm thinking maybe it would be better to use a USB to RS232 adapter?
I have one that is dedicated for programming my Yaesu VX-150 and FT-60 HT's. It has a 1/8" phone plug, not a 9D.
Logged
K0UA
Member

Posts: 1358




Ignore
« Reply #9 on: November 01, 2017, 05:47:05 PM »

I checked in the 450 CAT application manual and it does say use a straight cable.  I may have been the one to say use a nul modem cable but it is a straight cable.
Logged
NA4IT
Member

Posts: 42


WWW

Ignore
« Reply #10 on: November 02, 2017, 02:53:57 AM »

Forgot to look for my RS232 port. PC doesn't have one, but there is an IDC10 header on the mobo where a rear panel 9D would connect. I think I have the 9D connector, but I'm thinking maybe it would be better to use a USB to RS232 adapter?
I have one that is dedicated for programming my Yaesu VX-150 and FT-60 HT's. It has a 1/8" phone plug, not a 9D.

You can probably buy a 2 serial port card for less than $20 shipped...
Logged
KI7PLD
Member

Posts: 12




Ignore
« Reply #11 on: November 03, 2017, 08:31:40 AM »

^^^^^^^^THIS^^^^^^^^^^

Involving USB is opening a can of worms.

USB is much more susceptible to interference than RS232.

USB uses a much lower signal level than RS232 and is thus more easily influenced by outside forces.

Given that, proper grounding and good RF cable and connectors are more important than high zoot signaling cables.

If you seal up your signaling stuff too well how will you get clues you have an RF leak?   Cool
Logged
KE2KB
Member

Posts: 633




Ignore
« Reply #12 on: November 03, 2017, 09:10:07 AM »

^^^^^^^^THIS^^^^^^^^^^

Involving USB is opening a can of worms.

USB is much more susceptible to interference than RS232.

USB uses a much lower signal level than RS232 and is thus more easily influenced by outside forces.

Given that, proper grounding and good RF cable and connectors are more important than high zoot signaling cables.

If you seal up your signaling stuff too well how will you get clues you have an RF leak?   Cool
Thanks for that info. I'm glad I read it before I finished with my current Mouser order. I am going to order the 9-D Female connectors and use the shielded CAT6 cable I ordered in bulk.
I would think that if I pair the data lines (RXD & TXD) in a twister pr, handshake lines (RTS & CTS) in another, use metallic (or at least metal-ized) shells for the connectors, and bond the drain wire in the CAT6 cable only at one end (which end I am not sure), I will have a usable cable. I can install ferrites as necessary if I have any RFI, but I will be running no more than 100W, so hopefully this will not be a problem.

I did order a USB CAT cable for the Yaesu FT-450D on Amazon (from China) for $14, so it will be interesting to see whether I do indeed have RFI issues with the USB cable.

I had been looking on Ebay for a shielded 9-D Female to Female straight through cable, but only found two, and was somewhat disillusioned with both.

One question about the FT-450D and CAT:
What exactly will I be able to do with the CAT? I know that it is useful for logging, as most logging software will read the radio and enter the appropriate info automatically. But do I need CAT for digital modes as well?
What if I wanted to remotely control my FT-450D using my Android phone? Is there a method where I could use CAT connected to the PC, then use an app on the phone to communicate with the PC, and the radio?
But I would be interested in not only controlling the radio from my phone - I would actually want to operate the station, as I would be if I were sitting at the radio. I realize that I would need more than the CAT cable between the radio and the PC - I would also need an audio cable with PTT line, and if I wanted to run CW, I would want to control the keyer as well.
I understand the FCC rules would require me to provide an automatic shut-down of the transmitter within 3 minutes if the link failed. That can be accomplished using the FT-450D's Time-Out-Timer.

I suppose I could code my own apps (for the pc and phone) to do whatever I want to do, but at this point I am just playing with the possibilities.
I have heard/read about hams using Arduino to control remote stations, so that is probably the best option. I have yet to do anything with Arduino, but it sounds like a lot of fun!
Logged
KE2KB
Member

Posts: 633




Ignore
« Reply #13 on: November 03, 2017, 09:51:24 AM »

For connecting the CAT jack to the PC:
What is meant by this?



To me, it says connect pins 1,4, & 6 together.

Logged
AE5GT
Member

Posts: 33




Ignore
« Reply #14 on: November 03, 2017, 11:47:59 AM »

Foil sheilds are worthless at HF frequencies , a few db at best. . .
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!