eHam

eHam Forums => QRP => Topic started by: KA4NMA on March 17, 2013, 01:38:22 PM



Title: FT-817ND help
Post by: KA4NMA on March 17, 2013, 01:38:22 PM
I got  out my 817 after period of inactivity.  I went to check the swr using the 817.  I am getting some strange results.  At first I got no bars.  I tried later, and got several bars.  Then I got 2 bars.  What is going on?

Randy ka4nma


Title: RE: FT-817ND help
Post by: W4JST on March 17, 2013, 03:04:36 PM
Could be a loose connection.

Do you have an external SWR meter? I would check with that and see what it says. Then see if you have a loose jumper, antenna connector, moisture problem etc.


Title: RE: FT-817ND help
Post by: K8AXW on March 17, 2013, 06:15:51 PM
A comeback problem after long inactivity can usually be caused by crudded up connectors, switches and controls, relay contacts and or antenna problems.

In order to suggest a logical plan for correcting your problem I would like to know if you have a dummy load and an SWR meter?

If you have neither, then you could "shotgun" it and get a can of contact cleaner (this in itself requires some research and investigation to avoid buying a product that disolves plastics, etc.) and start with the switches and controls in the radio.  If the radio has an antenna changeover relay then the contacts could be cleaned with a piece of paper pulled between the contacts while pushing on the relay arm.

Don't forget to clean the SO-239 or BNC antenna connector, whichever it has.  

If it's and antenna problem, then an SWR meter is necessary to confirm this.



Title: RE: FT-817ND help
Post by: KA4NMA on March 17, 2013, 09:17:17 PM
I am using a Miracle Ducker TL connected directly to rear antenna on my ft-817nd.  I do not have a dummy load or swr meter.  I do have a MFJ antenna analyzer.   Sounds like I might need to adjust the antenna per instructions and then remove and attach it to the antenna analyzer.

Randy ka4nma


Title: RE: FT-817ND help
Post by: K8AXW on March 18, 2013, 09:56:16 AM
Randy, wouldn't it be more logical to connect the antenna to the analyzer and adjust the antenna as per the instructions? 

When you get what you're supposed to then connect it to the rig and see whatkind of "bars" you're getting.


Title: RE: FT-817ND help
Post by: KATEKEBO on March 18, 2013, 12:04:08 PM
I have quite a lot of experience with the Miracle Whip / Ducker.  One thing comes to my mind immediately.

Are you using a counterpoise wire?  Or anything that would act as an counterpoise wire (for example, power supply cable and an external power supply)?

Without a counterpoise wire, the SWR will depend very much on any other object attached / close to the radio.  Your hand, the mic cable, etc. - anything attached to the radio is now the counterpoise.  The same applies if you place your hand close to the Miracle Ducker tuning knob or not.  Do a simple test.  Adjust the SWR to the lowest number while holding the knob, and then move your hand away.  I bet the SWR will change by a couple of "bars".  It's less of a problem on shorter bands (10 and 15 m), but absolutely critical on longer bands (20, 30 and 40 m, the Miracle Ducker is pretty much useless beyond 40 m).

The Miracle Ducker is essentially a short vertical radiator and it MUST have a counterpoise / ground plane to work properly.  Without it, it's completely unpredictable.

The only way to cure this problem is to ground you radio or provide appropriate counterpoise wire.

S. Bucki
KD8KQH



Title: RE: FT-817ND help
Post by: KA4NMA on March 18, 2013, 02:05:24 PM
I did make a counterpoise for the antenna.  I used a ring terminal what slides over the BNC.  I then laid out the wire around the apartment.

Randy


Title: RE: FT-817ND help
Post by: KATEKEBO on March 18, 2013, 04:26:15 PM
I don't think a ring around the BNC connector will provide reliable connection.  This could actually explain the wild changes in SWR.  Try connecting the counterpoise wire to the radio grounding screw in the back, just under the rear antenna connector.
Another issue may be misaligned connection inside the Miracle Ducker tuner itself.  If the sliding arms is not perfectly aligned, it sometimes touches two adjacent pads at the same time, causing swings in SWR.
S. Bucki
KD8KQH


Title: RE: FT-817ND help
Post by: N5RWJ on March 21, 2013, 01:54:04 PM
I wonder when a new version of the FT-817  will come out?


Title: RE: FT-817ND help
Post by: K5LXP on March 22, 2013, 06:54:46 AM
I wouldn't worry too much about the results you're seeing.   It's not like you'll be making contacts with that setup anyway.  The only thing you'll be working is your next door neighbor's PC speakers with a miracle whip antenna on a QRP rig inside of an apartment.  Seriously - I wouldn't waste my time with an antenna like that.  QRP indoors is a challenge enough without piling a minus 20dB antenna on it.

Mark K5LXP
Albuquerque, NM


Title: RE: FT-817ND help
Post by: LA9XSA on March 22, 2013, 05:04:57 PM
Unless you have a metal floor in a wooden house or something, I'd avoid an indoor vertical. Could it be that the antenna is severely detuned by nearby objects or something? (Like house wiring, metal siding, etc.)

You can still make contacts on CW and PSK-31 on something like that, if you get it to match, but if you want to have a better indoor antenna, get a dipole up in the attic or even a wooden ceiling. I've been lucky enough to even work SSB DX on my FT-817 on ceiling dipoles.