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: Yaesu FC-40 Autotuner, HSWR and Unun?  (Read 22447 times)
N4SRN
Member

Posts: 303




Ignore
« on: August 10, 2014, 06:27:44 AM »

Hi,

I've installed a Yaesu FC-40 autotuner with my Yaesu FT-897D base for use with random wire antennas. Right now, I'm trying to get it to tune a raingutter antenna, but it will not tune on any band, indicating High SWR (HSWR), which is not unexpected, as I understand from my reading.

The antenna (gutter) connection is an insulated solid copper 12g wire screwed to a downspount and connected to the FC-40 antenna terminal. The FC-40 ground post connects to both a 8ft ground rod and 1/4 wavelength counterpoise wires (for 10m, 17m, 20m, 40m) running in a bundle 2ft above ground, along my foundation, 30ft below my gutter. The antenna feed wire and ground wire are probably too long - I need to drill some holes for more direct and shorter connections. Both wires travel together for a few feet, which is probably not good too. A DIN cable on the FC-40 connects to the CAT port on the FT-897D to control the unit and a coax cable connects the FC-40 to HF antenna ports.

I have heard about use of a 9:1 unun with random wires and found a Buxcomm B2KLW91 9:1 unun that has an antenna wire top post, a SO239 coax bottom connector, and a side ground post. I can't see where/how I might use this with the FC-40. Or if another unun format is appropriate to get the SWR down to where the FC-40 might manage to tune at all.

Appreciate comments and recommendations!
Logged

Bret/N4SRN
Bedford, NH  USA
KH6AQ
Member

Posts: 7718




Ignore
« Reply #1 on: August 10, 2014, 06:43:57 AM »

I would first check that the autotuner is working correctly. An 8'3"antenna wire and an 8'3" ground wire can be connected to the tuner (route them inside the house). It should be able to tune this on the 10 meter band.
Logged
N4SRN
Member

Posts: 303




Ignore
« Reply #2 on: August 10, 2014, 05:12:07 PM »

Thanks for the suggestion. I'd like to try your plan, but I'm not sure what you mean "route them inside the house".

The FC-40 is inside the garage by the garage door, with the FT-897D just above on ground floor. The FC-40 is mounted inside garageabout 2ft above ground level, that is, if I drill out just below the FC-40 to outside, ground is 2ft below. Antenna coax and DIN8 control cables penetrate wall and run up to window pass-thru about 8ft up to ground floor, with FT-897D just inside window. Ground rod is just behind wall FC-40 is mounted on, maybe 2ft down and 2ft away.

I'm thinking what you want me to do is:
1. Attach a 8'3" wire to antenna terminal running anywhere
2. Attach a 8'3" wire to ground terminal connected to ground rod

Would that be correct?
Logged

Bret/N4SRN
Bedford, NH  USA
WB6BYU
Member

Posts: 17042




Ignore
« Reply #3 on: August 10, 2014, 06:59:12 PM »

Quote from: WQUD444

2. Attach a 8'3" wire to ground terminal connected to ground rod

Would that be correct?



NO!

The wire on the ground terminal is NOT connected to the ground rod - it is a 1/4 wave
radial with the far end open circuited.

This is one of those quirky things that makes sense only once you understand how
impedances are transformed along an antenna wire.  A wire connected to a ground
rod at one end and your tuner at the other is no RF ground at all - basically
equivalent to an open circuit rather than a low impedance path to ground.  That's
because it acts like an impedance transformer:  a low impedance at one end looks
like a high impedance at the other, and vice versa.  And the 8 1/4' wire is 1/4
wavelength on 10m.

While a 4' wire to a ground rod is better than nothing on 10m, it is still on the long
side for effective operation.   Probably work OK on 40m, however.


The FC-40 does have some limitations on what impedances it can match.  Like most
relay-switched tuners it won't match and end-fed half wave antenna (due to the high
voltages across the feedpoint and the limited voltage rating of the relays.)  If your
antenna happens to be about 65' long it could be a problem on 40m, 20m and 15m.

Also, make sure you have good connections throughout the antenna:  rain gutters and
down spouts often don't (though "continuous aluminum gutters" are a step in the right
direction.)  Usually this means putting a couple stainless steel sheet metal screws through
each joint.  (If you have vinyl gutters, run a wire inside or along them.)  Stainless is better
than galvanized steel in this case to reduce corrosion due to dissimiliar metals.


The 8' wires are a good test of the tuner, because there are a number of parameters that
might not be set up properly.
Logged
WD8KNI
Member

Posts: 173




Ignore
« Reply #4 on: August 10, 2014, 11:26:55 PM »

Just looked up the specifications of the FC-40, "Antenna matching impedance: 16.5 to 150 Ohms" (Universal Radio website, Yaesu manual does not say what the impedance is it only says Current fed don't use ½ wavelength antenna).  Hate to tell you but if Universal is correct this tuner belongs in the junk pile.. I would not trust their information) if you look at the MFJ BRT-994BRT it covers a range of 6-1600 ohms at 300 watts, and MFJ is not a tuner I would consider to be one of the best. 

I suspicion the problem you are having is with antenna length with the tuner you have chosen, it is more critical when the tuner does not have the range to tune a wire length you have.  Make sure you reset the tuner when you change antenna lengths.. and the jumpers are set inside the radio for external tuner..
 
as for ground rod.. both counterpoise and ground rod (two wires) don't ground the end of the counterpoise.   

..Fred
Logged
G8JNJ
Member

Posts: 655


WWW

Ignore
« Reply #5 on: August 11, 2014, 01:03:08 AM »

Hi,

The Universal spec is incorrect.

The FC-40 has about the same matching range as most of the others of this type.

It's a switched L with a max inductance of about 12uH and capacitance of about 2000pF

The circuit can be found here.

http://yaesu.com/downloadFile.cfm?FileID=4778&FileCatID=158&FileName=FC-40_OM_ENG_EAD77X101.pdf&FileContentType=application%2Fpdf

Yaesu claim operating Frequency Range: 1.8 - 54 MHz with 20+ m end-fed wire, 7 - 54 MHz with YA-007 HF 2.5 m Mobile whip Antenna.

You shouldn't need to use an additional Unun, but avoid 1/2 wave lengths of wire on the bands you want to use. Because the pre-WARC Amateur bands are harmonically related, a 1/4 wave on 80m is also a 1/2 wave on 40m. When using auto-tuners like this it is better to pick a length of wire that IS NOT resonant on any of the amateur bands to avoid these problems. It also helps if you can use thicker wire or aluminium tube as the radiating element. Having a larger diameter of conductor reduces the feed impedance of 1/2 wave antennas from values of around 5K Ohms for a thin wire, to around 1.5 K Ohm for a 1/4" diameter conductor and a few hundred Ohms for 2" or greater diameter self supporting aluminium tube. This is why 33' or 43' verticals made from aluminium tube can be matched easily with a 4:1 Unun at the base.

Some more information can be found here

http://vk6ysf.com/longwire_antenna.htm

If you want to read about wide bandwidth no tuner verticals and the background to such designs try this link.

http://www.tc2m.info/TC2M%20HF%20Vertical%20G8JNJ.pdf

Regards,

Martin - G8JNJ

www.g8jnj.net
www.tc2m.info



Logged
N4SRN
Member

Posts: 303




Ignore
« Reply #6 on: August 11, 2014, 04:39:10 AM »

Thanks All. I'm traveling this week but will try a reset and 8'3" wire antenna and ground next weekend.

The raingutter thing might not work out, so I might look to string a regular long-wire antenna. I picked up 500ft of 26g Polystealth wire for a try - it's thin and weak, but with the right pulley suspennsion, might survive tree sway. The route would be 3ft up the garage wall from FC-40 to ceiling, 30ft across the garage ceiling, through the opposite garage wall and up 15ft to a 2nd story window, then a long shot to however high I can get in a ~100ft pine about 100ft from the house. Slingshot and pull method (envisioned). I'll refer to VK6YSF's length chart.
Logged

Bret/N4SRN
Bedford, NH  USA
GOUDURIX
Member

Posts: 222




Ignore
« Reply #7 on: August 13, 2014, 02:41:10 AM »

I have a rather unpleasing advice: I've had the yaesu FC-40 ATU with my Yaesu FT-897 and was very dissatisfied with it. I tried it out at home QTH with inverted-L's before wanting to use it on my sailing boat to match an end-fed sloping wire antenna against a mixed RF-ground system (short copper-tape connection to the seawater, cut radials for 40m-20m-17m-15m bands) and some other metal hardware on the boat.

This atu has simply a too limited impedance matching range (I have never seen the official data but I think it is rather 150-600 Ohms not better...).

I've tried countless solutions changing wire length, parallel fed wires, even one of the best wire lengths favouring 40m-10m operation (staying away as far as possible from 1/2 wave or its multiples) which is 9.2 meters it always had some bands where it couldn't match and gave the dreaded "HSWR" notice....

I finally trhew it out and replaced it by an SGC-230. What a difference! It tunes it all in between 3.6 MMhz and 30 Mhz even the marine SSB frequencies.
remark: this doesn't prove I have an efficient antenna system on any given frequency but at least that it has a far better impedance matching range!

At home I installed the cheaper CG-3000 tu tune a 9.2m vertical with 4 elevated radials per band. It provides a better match than the FC-40 but less than the CG-231.

My (personal) end conclusion: The FC-40 is OK for a limited number of chosen bands requiring carefully chosen wire lengths. Its only avantage when using with FT-897 or FT-857 is the "tune-one-push" function. The CG-231 is the BMW of the affordable ATU's.

Jan

Logged
GOUDURIX
Member

Posts: 222




Ignore
« Reply #8 on: August 13, 2014, 05:30:19 AM »

Correction:
" The SGC-231 is the BMW of affordable ATU's"

To add: sure I've also tried 4:1 - 9:1 even 16:1 UNUN's that didn't help for a wide-band-range kind of use.

Jan

PS: BTW I don't regard myself as an Elmer just a user having experience with the FC-40
Logged
N4SRN
Member

Posts: 303




Ignore
« Reply #9 on: August 17, 2014, 07:00:21 AM »

OK - I connected two 8'3" insulated 22g copper standed wires to the antenna and ground posts of the FC-40 (no other wires connected to either post, and both wire extended horizontal and perpendicular to one another and taped to non-conductive walls) and tried to tune mid-band on 10m (28.85 MHz), 15m (21.125 MHz), 20m (14.175 MHz), 40m (7.150 MHz) and 80m (3.750 MHz) and got HSWR on the FT-897D on all, both with and without a Radio Works T-4-Plus Line Isolator between FC-40 and radio.

I hooked up a RIGEXPERT AA-600 Antenna Analyzer to the antenna feedline and saw 10m (SWR 15.5), 20m (SWR infinite), 40m (SWR 3.0) as well as 2m (SWR 6.1 and 70cm (SWR 4.0).  This was after last having attempted to tune with FC-40 on 10m. If I reconnected and attempted to tune on 80m, then connected to the AA-600, I got the same values for all except 10m (SWR 16.5). That is, the FC-40 appears left in the same state after attempting to tune at 10m or 80m.

My configuration:
1. 3ft RG-8X from FT-897D to window pass-thru, supplied Yaesu FC-40 5m coax cable from pass-thru to FC-40
2. Supplied Yaesu FC-40 c5m control cable to CAT in on FT-897D. Ferrite Mix 31 beads on both ends of the control cable, as recommended.
3. FT-897D Menu #20 abd #85 both set to TUNER and TUNR appears on FT-897D display
4. When I select to tune via A button, the TURN changes to WAIT and I hear noise from the FT-897D for 1-2 seconds before if displays HSWR
5. FT-897D is grounded via a 1/2" tinned copper strap to 8' copper-clad ground rod (planning to bond with AC service panel ground soon via a central copper ground bus plate at station)

Not good... I'll do the FC-40 reset process and repeat.
Logged

Bret/N4SRN
Bedford, NH  USA
KG4RUL
Member

Posts: 3059


WWW

Ignore
« Reply #10 on: August 17, 2014, 07:18:39 AM »

Unless you have securely bonded each section of the rain gutter system together, you will have a series of non-linear junctions as an antenna.
Logged
N4SRN
Member

Posts: 303




Ignore
« Reply #11 on: August 17, 2014, 08:21:19 AM »

Unless you have securely bonded each section of the rain gutter system together, you will have a series of non-linear junctions as an antenna.

I'm sure you're right about that, but in my latest post I refer to the 8'3" wire test.
Logged

Bret/N4SRN
Bedford, NH  USA
N4SRN
Member

Posts: 303




Ignore
« Reply #12 on: August 17, 2014, 08:36:41 AM »

OK - I connected two 8'3" insulated 22g copper standed wires to the antenna and ground posts of the FC-40 (no other wires connected to either post, and both wire extended horizontal and perpendicular to one another and taped to non-conductive walls) and tried to tune mid-band on 10m (28.85 MHz), 15m (21.125 MHz), 20m (14.175 MHz), 40m (7.150 MHz) and 80m (3.750 MHz) and got HSWR on the FT-897D on all, both with and without a Radio Works T-4-Plus Line Isolator between FC-40 and radio.

I hooked up a RIGEXPERT AA-600 Antenna Analyzer to the antenna feedline and saw 10m (SWR 15.5), 20m (SWR infinite), 40m (SWR 3.0) as well as 2m (SWR 6.1 and 70cm (SWR 4.0).  This was after last having attempted to tune with FC-40 on 10m. If I reconnected and attempted to tune on 80m, then connected to the AA-600, I got the same values for all except 10m (SWR 16.5). That is, the FC-40 appears left in the same state after attempting to tune at 10m or 80m.

My configuration:
1. 3ft RG-8X from FT-897D to window pass-thru, supplied Yaesu FC-40 5m coax cable from pass-thru to FC-40
2. Supplied Yaesu FC-40 c5m control cable to CAT in on FT-897D. Ferrite Mix 31 beads on both ends of the control cable, as recommended.
3. FT-897D Menu #20 abd #85 both set to TUNER and TUNR appears on FT-897D display
4. When I select to tune via A button, the TURN changes to WAIT and I hear noise from the FT-897D for 1-2 seconds before if displays HSWR
5. FT-897D is grounded via a 1/2" tinned copper strap to 8' copper-clad ground rod (planning to bond with AC service panel ground soon via a central copper ground bus plate at station)

Not good... I'll do the FC-40 reset process and repeat.

I did the reset and no go:

1. Powered off FT-897D
2. Took off cover and set 4th dip switch to ON, as per http://www.yaesu.com/downloadFile.cfm?FileID=1125&FileCatID=156&FileName=FC%2D40%5FNew%20Product%20News.pdf&FileContentType=application%2Fpdf , but saw no glowing green LED. The PCB must have changed, as there was no D1002 labeled. Waited and set dip back to off.
3. Check DIN8 pins - all look unbent.
4. Disconnected tuner control cable and antenna from FT-897D and set Menu #20 & #85 back to defaults and powered off.
5. Powered on and set Menu #20 to TUNER. Powered off and connected controller and antenna cables, powered on and set Menu #85 to TUNE. Cycled power again.
6. Selected Multi-function row k and pressed a for TUNE. Instructions say button A TUNE should be now bracketed with parentheses, but it's not. TUNR appears in upper right display.
7. On all bands, pressing button A for TUNE yield WAIT and then TUNE reappears with HSWR.

I'm not sure if PDF instructions are out-of-date on glowing LED on reset, and parentheses on TUNE, or if I have a hardware problem...
Logged

Bret/N4SRN
Bedford, NH  USA
N4SRN
Member

Posts: 303




Ignore
« Reply #13 on: August 19, 2014, 06:24:50 AM »

I put up a 135ft 26g Long Wire Polystealth antenna and connected to the FC-40 ATU - still HSWR on all bands.

When I spoke with Yaesu Technical Support, they suggested tuning to a Dummy Load, so I attached a 50ohm VSWR<1.15 load and tried to tune 10-80m and got HSWR on all bands. I'll ring them back and ask what next...
Logged

Bret/N4SRN
Bedford, NH  USA
VR2KJ
Member

Posts: 2




Ignore
« Reply #14 on: September 11, 2017, 09:47:06 PM »

What is wrong ,
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!