I need to extend the control cable for my AH-4 tuner. I have lots of Cat 5
Ethernet cable. The four leads to the tuner are Key, Start, +13.8Vdc, and
Ground. I initially hooked up each to each of the four pairs in the Ethernet
cable (i.e., Key to Blue/Blue-White). My thinking was parallel each pair so
I have less current loss, but I think I blew the capacitance out of the
water and the Key/Start pulses are getting smeared along the 100+ foot run.

What's the best way to wire things up so to the twisted pairs so any RFI
gets nulled out? Ground to each of the 4 White leads, and Key to say Blue,
Start to Green, and +13.8V to Orange? That way each twisted pair would have
a "signal" and ground. Or I could use the Brown for Ground, and connect the
AH-4 factory cable's shield to the four white leads. Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key pulse
signals?

Jon - KB1HTW

On Wed, 2 Feb 2005 15:09:14 -0500, "Jon KB1HTW"
wrote:

Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key pulse
signals?

Hi Jon,

Use RS-422 components to translate voltage signals into current
signals, and then back (at the other end) to voltage signals. If you
have surplus twisted pairs, then this will give you the
transmission/length requirements.

73's
Richard Clark, KB7QHC

Thanks for the info, but I don't think it'll work.

From http://home.comcast.net/~hamlakemn/ah4/ah4.htm (great site for AH-4
info, by the way!)

"The AH-4 uses 12 volt inverted logic and an "open collector" transistor to
ground to perform signaling. The radio provides 13.8 volts to the tuner. It
also provides a START line that is pulled up to 13.8 volts inside the radio.
The radio pulls the START line to ground to assert the signal (start the
tuning operation). Similarly, the AH-4 pulls the KEY line to 5 volts through
a 22 kohm resistor/diode combination. The radio also pulls this line to 13.8
volts through a resistor. The AH-4 pulls this line to ground to assert the
signal (indicate tuning status to the radio.)."

I think it may be more effort than it's worth. Plus, I'm not sure if what I
described as the "problem" is really the cause - I just think it was the
most likely candidate. I guess I need to check the end of the cable and see
if I'm getting better than 12V at the tuner. The author of that website says
he's been able to control the tuner using 18 gauge rotor cable up to 60
meters away. My Cat 5 Ethernet cable is probably 24 or 26 gauge solid core -
that's why I paralleled the leads. Another possible cause why the tuner
can't tune any band is that my temporary ground is probably pretty poor. The
tuner's on the roof, feeding a long wire - 14 AWG copperweld, ~73' I just
tied the RF ground terminal on the tuner to an old 10 AWG aluminum lightning
ground wire that goes down to the electrical service entrance of my house.
The ground there is a cold water pipe augmented with an 8' length of 1/2"
copper pipe driven 6' into sandy/rocky ground.

Since the AH-4 is supposedly capable of driving a dipole - with the tuner at
the center, I think I'll try stringing up another wire as a counterpoise.
Only I don't have 150' linear feet of space on my property, so the dipole
will end up being a sort of a "J-pole" being fed at the center...

Good thing is that I live on a harbor in Massachusetts, so as soon as the
weather's better (like May? ;-( ), I should be able do drive some ground
rods next to the seawall, where they'll be in sal****er-saturated sand.
Hopefully they'll last a few years... I'm itching to get my IC-706Mk2G up
and running HF - 2m/70cm works fine...


"Richard Clark" wrote in message
...
On Wed, 2 Feb 2005 15:09:14 -0500, "Jon KB1HTW"
wrote:

Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key
pulse
signals?

Hi Jon,

Use RS-422 components to translate voltage signals into current
signals, and then back (at the other end) to voltage signals. If you
have surplus twisted pairs, then this will give you the
transmission/length requirements.

73's
Richard Clark, KB7QHC

More info, Richard:

I climbed up on my roof last night (from my 3rd floor balcony - always an
adventure!) with a flashlight to check my RF ground - sure enough the old
cable had a splice that was broken in one place (that I could find in the
dark). So I fixed that. I also verified that the internal fuse of my radio
(IC-706) wasn't blown (the tuner connector on the back of the radio still
put out +13.8Vdc.

When I plugged everything back in, I figured I'd at least be able to tune at
least a couple of the bands, but I was met with - nothing. Pressing the Tune
button on the radio for two seconds would do absolutely nothing - no
changing mode to CW and keying for transmit, not even a short beep saying
the tuner couldn't tune the long wire. Just dead.

By then my wife was dragging me out for dinner, and it was too late after
for any troubleshooting. And this weekend, I'll be out of town, so I won't
be able to do any serious troubleshooting during daylight hours for another
week and a half.

Man, this is frustrating...


"Jon KB1HTW" wrote in message
...
Thanks for the info, but I don't think it'll work.

From http://home.comcast.net/~hamlakemn/ah4/ah4.htm (great site for AH-4
info, by the way!)

"The AH-4 uses 12 volt inverted logic and an "open collector" transistor
to ground to perform signaling. The radio provides 13.8 volts to the
tuner. It also provides a START line that is pulled up to 13.8 volts
inside the radio. The radio pulls the START line to ground to assert the
signal (start the tuning operation). Similarly, the AH-4 pulls the KEY
line to 5 volts through a 22 kohm resistor/diode combination. The radio
also pulls this line to 13.8 volts through a resistor. The AH-4 pulls this
line to ground to assert the signal (indicate tuning status to the
radio.)."

I think it may be more effort than it's worth. Plus, I'm not sure if what
I described as the "problem" is really the cause - I just think it was the
most likely candidate. I guess I need to check the end of the cable and
see if I'm getting better than 12V at the tuner. The author of that
website says he's been able to control the tuner using 18 gauge rotor
cable up to 60 meters away. My Cat 5 Ethernet cable is probably 24 or 26
gauge solid core - that's why I paralleled the leads. Another possible
cause why the tuner can't tune any band is that my temporary ground is
probably pretty poor. The tuner's on the roof, feeding a long wire - 14
AWG copperweld, ~73' I just tied the RF ground terminal on the tuner to an
old 10 AWG aluminum lightning ground wire that goes down to the electrical
service entrance of my house. The ground there is a cold water pipe
augmented with an 8' length of 1/2" copper pipe driven 6' into sandy/rocky
ground.

Since the AH-4 is supposedly capable of driving a dipole - with the tuner
at the center, I think I'll try stringing up another wire as a
counterpoise. Only I don't have 150' linear feet of space on my property,
so the dipole will end up being a sort of a "J-pole" being fed at the
center...

Good thing is that I live on a harbor in Massachusetts, so as soon as the
weather's better (like May? ;-( ), I should be able do drive some ground
rods next to the seawall, where they'll be in sal****er-saturated sand.
Hopefully they'll last a few years... I'm itching to get my IC-706Mk2G up
and running HF - 2m/70cm works fine...

On Thu, 3 Feb 2005 09:58:31 -0500, "Jon KB1HTW"
wrote:

More info, Richard:

I climbed up on my roof last night (from my 3rd floor balcony - always an
adventure!) with a flashlight to check my RF ground - sure enough the old
cable had a splice that was broken in one place (that I could find in the
dark). So I fixed that. I also verified that the internal fuse of my radio
(IC-706) wasn't blown (the tuner connector on the back of the radio still
put out +13.8Vdc.

When I plugged everything back in, I figured I'd at least be able to tune at
least a couple of the bands, but I was met with - nothing. Pressing the Tune
button on the radio for two seconds would do absolutely nothing - no
changing mode to CW and keying for transmit, not even a short beep saying
the tuner couldn't tune the long wire. Just dead.

By then my wife was dragging me out for dinner, and it was too late after
for any troubleshooting. And this weekend, I'll be out of town, so I won't
be able to do any serious troubleshooting during daylight hours for another
week and a half.

Man, this is frustrating...


"Jon KB1HTW" wrote in message
...
Thanks for the info, but I don't think it'll work.

From http://home.comcast.net/~hamlakemn/ah4/ah4.htm (great site for AH-4
info, by the way!)

Hi Jon,

I consulted the page you offered and given the timing diagrams I would
suggest there are no issues of risetime on leading edges of the logic.
The microprocessor appears to be a state machine looking at levels,
not edges. Anyway, the timings are extremely long in comparison to
any edge issues at these scales. Even with a mile of wire, the timing
is too simple to be upset by slope.

You should have (or now do) designed this and assembled it on the
bench for testing in a warm place (for your sake). Replace the cable
so there are NO splices anywhere (if you found one broken, that is
pilot error).

As for the size of wire. This will never be a problem unless you are
running in the 40s of gauge. You MUST however meet the peak current
demand. This is for the benefit of the 22 relays. You must confirm
the average current demand meets spec too for the benefit of the
control circuitry.

Skip the attention being placed on the ground lead down. As long as
it is long (and on the roof of a three floor home, length is
sufficient) it hardly matters, RF-wise, what it ties to. The only
point about it going to ground is for the sake of lightning protection
(which seems a matter of luck anyway in this configuration).

I see no discussion of choking either the transmission line nor the
control lines on this page. This is poor coverage (or I simply
scanned it too fast). This may/may not change your situation, but
using them is standard procedure.

Get an O'scope and tie it to the control lines and confirm the timing
diagrams illustrated at the link offered. If you have no O'scope,
then patch a meter across the lines and at least confirm a twitch of
the needle. This won't prove much - unless there is no twitch. The
timing suggests this would be long enough to overcome the ballistics
of needle mass. If you have a digital VOM, and it offers AC Peak hold
reading, this should resolve at least one change of state - it will
not distinguish between the fail indication timing waveform and normal
operation illustrated at the link however.

If you have the bench talent, you could assemble a simple pulse
stretcher from ICs to aid in this troubleshooting. If you are very
talented, you could assemble ICs to stretch, clock, gate, and resolve
the fail indication waveform. An O'scope is far simpler and by far
the surest method.

73's
Richard Clark, KB7QHC

Jon,

get your control cable choked before trying anything else. You can use a
pair of split core ferrite beads. Put them close to the cable's ends to stop
induced RF from getting into the circuits.706MKIIG is sensitive to that.
Better then, get a larger core diameter and make as many turns as you can
fit. Same thing applies when you want to extend the control's head cable.
A better option would be to use a shielded cable, not TP. What happens is
that your cable works as an antenna, feding RF back into the radio which may
cause unpredictable results. In case of the remote control head this simply
shuts the radio down when trying to key it.
But you still should be able to get away with your existing TP cable if you
chop the RF off at both ends.

--

Regards,
Ivan

"Richard Clark" wrote in message
...
On Thu, 3 Feb 2005 09:58:31 -0500, "Jon KB1HTW"
wrote:

.... I see no discussion of choking either the transmission line nor the
control lines on this page. This is poor coverage (or I simply
scanned it too fast). This may/may not change your situation, but
using them is standard procedure.

... Richard Clark, KB7QHC

Been out of town - haven't had time to try anything yet. What size chokes
would you recommend? I can stop by RatShack on the way home, or possibly
detour up to HRO in Salem, NH...

Isn't the 706 supposed to use something like 300mW for tuning? Shouldn't
this be under the threshold for RF interfering with the tuning control lead?
I mean, if I can send Ethernet frames at a rate of 1Gb/s down a Cat 5 cable
error free, you'd think I wouldn't have trouble with 300msec pulses...

Jon

"Ivan Makarov" wrote in message
...
Jon,

get your control cable choked before trying anything else. You can use a
pair of split core ferrite beads. Put them close to the cable's ends to
stop
induced RF from getting into the circuits.706MKIIG is sensitive to that.
Better then, get a larger core diameter and make as many turns as you can
fit. Same thing applies when you want to extend the control's head
cable.
A better option would be to use a shielded cable, not TP. What happens is
that your cable works as an antenna, feding RF back into the radio which
may
cause unpredictable results. In case of the remote control head this
simply
shuts the radio down when trying to key it.
But you still should be able to get away with your existing TP cable if
you
chop the RF off at both ends.

--

Regards,
Ivan

"Richard Clark" wrote in message
...
On Thu, 3 Feb 2005 09:58:31 -0500, "Jon KB1HTW"
wrote:

... I see no discussion of choking either the transmission line nor the
control lines on this page. This is poor coverage (or I simply
scanned it too fast). This may/may not change your situation, but
using them is standard procedure.

.. Richard Clark, KB7QHC

On Wed, 02 Feb 2005 15:09:14 -0500, Jon KB1HTW wrote:

I need to extend the control cable for my AH-4 tuner. I have lots of Cat 5
Ethernet cable. The four leads to the tuner are Key, Start, +13.8Vdc, and
Ground. I initially hooked up each to each of the four pairs in the Ethernet
cable (i.e., Key to Blue/Blue-White). My thinking was parallel each pair so
I have less current loss, but I think I blew the capacitance out of the
water and the Key/Start pulses are getting smeared along the 100+ foot run.

What's the best way to wire things up so to the twisted pairs so any RFI
gets nulled out? Ground to each of the 4 White leads, and Key to say Blue,
Start to Green, and +13.8V to Orange? That way each twisted pair would have
a "signal" and ground. Or I could use the Brown for Ground, and connect the
AH-4 factory cable's shield to the four white leads. Which is the preferred
route for minimizing RFI or cable capacitance affecting the Start/Key pulse
signals?

Jon - KB1HTW

Try using a shielded 4 conductor cable. All the stuff about ferrites is
good but if you can prevent pickup in the first place, that is better.
Also try ferrite beads on the ICOM interface control wires inside the
tuner.

I have much used an AH-4 tuner in conjunction with an Icom IC-735
transceiver for 5 or 6 years or more. On all bands 160 to 10m.

The tuner has always been located at the base of various end-fed antennas.
The tuner control unit has always been bolted, as intended, to the side of
transceiver. The transceiver has been used in three different rooms, at
different times, in the house with varying lengths of control cable and coax
running through 1" holes in brick walls.

The control cable to the tuner has varied in length and distance from a few
feet to about 30 feet.

The system has always worked fine. No chokes, ferrites or anti-RFI measures
have ever been used. No RFI has been experienced. No faults have occurred
except that one dial lamp in the IC-735 has failed and I'm too old to fix
it.

The length of control cable has been varied simply by inserting a length of
unscreened, thin-wire, pvc-sheathed cable, 5/16" diameter, using soldered
joints and an open-to-the-air tag strip.

At present there is an excess length of control cable, of unknown length,
which is strewn around the floor, partly coiled up, at the back of a long
bench. But no TVI.
----
Reg, G4FGQ

Had time last night only to take the tuner down off the roof and put it
inside my shack, just inside the window. Extended the long wire another 60+
feet using insulated 14AWG stranded speaker wire running across the roof
from the original wire's anchor point on one edge, down to the window, so
now it's 135'+. RF ground is now a 45` length of the same 14AWG wire running
anong the deck and ground. Opened up the tuner and verified that I have
supply sufficient voltage at the tuner (13.7Vdc). Placed sleeved ferrite
cores on both the radio end and the tuner end of the control cable. Tried
tuning at 40/20/17/6m - still not working.

It's a killer when I can only work on it 20 minutes at a time. Hopefully
Saturday or Sunday I can try a bit more focused troubleshooting, assuming
the coming Nor'easter isn't too bad. I thought I'd try making it drive a
balanced dipole (if I can pick up some 450 ohm ladder line this week), 75'
each leg. They won't be straight, more like a J with the tuner at the
mid-point.


"Ivan Makarov" wrote in message
...
Jon,

get your control cable choked before trying anything else. You can use a
pair of split core ferrite beads. Put them close to the cable's ends to
stop
induced RF from getting into the circuits.706MKIIG is sensitive to that.
Better then, get a larger core diameter and make as many turns as you can
fit. Same thing applies when you want to extend the control's head
cable.
A better option would be to use a shielded cable, not TP. What happens is
that your cable works as an antenna, feding RF back into the radio which
may
cause unpredictable results. In case of the remote control head this
simply
shuts the radio down when trying to key it.
But you still should be able to get away with your existing TP cable if
you
chop the RF off at both ends.

--

Regards,
Ivan

"Richard Clark" wrote in message
...
On Thu, 3 Feb 2005 09:58:31 -0500, "Jon KB1HTW"
wrote:

... I see no discussion of choking either the transmission line nor the
control lines on this page. This is poor coverage (or I simply
scanned it too fast). This may/may not change your situation, but
using them is standard procedure.

.. Richard Clark, KB7QHC