I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

I had this problem myself once. RF was getting in through the
Microphone connector. ferrite on the Mic cable corrected it for me.

Good luck,

Bruce , N1RX

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

I had this problem myself once. RF was getting in through the
Microphone connector. ferrite on the Mic cable corrected it for me.

Good luck,

Bruce , N1RX

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

I had this problem myself, years ago. Turns out, the RF was getting in
through the Mic cable. If you still have the mic connected, even
though you are putting your data in through the back, try
disconnecting the Mic, or using ferrite on the mic cord right at the
front panel connector. Good luck.

Bruce, N1RX

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

I had this problem myself, years ago. Turns out, the RF was getting in
through the Mic cable. If you still have the mic connected, even
though you are putting your data in through the back, try
disconnecting the Mic, or using ferrite on the mic cord right at the
front panel connector. Good luck.

Bruce, N1RX

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

The RF is definitely getting into the data audio as the mic is not
plugged in and the mute line is grounded.
The effect is that the transmitter runs full power rf out regardless
of gain setting. When it is stable the power controls smoothly with
the tx (mic) gain control.
Richard

Leigh W3NLB wrote:

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

Are you sure it's only in data mode? And are you sure it's RF getting
in? I'm asking because data is more sensitive to frequency variations
than most other modes.

There is a known problem with the VCO in this radio. Contamination of
a conformal coating designed to protect the components from humidity
is actually hygroscopic. The fix is to remove the coating and replace
it with hot-melt glue.

Any Kenwood warranty station will perform this mod under warranty on
any TS-440, regardless of whether you were the original purchaser (or
they used to... I can't speak for Kenwood).


73 de Leigh W3NLB

The RF is definitely getting into the data audio as the mic is not
plugged in and the mute line is grounded.
The effect is that the transmitter runs full power rf out regardless
of gain setting. When it is stable the power controls smoothly with
the tx (mic) gain control.
Richard

Leigh W3NLB wrote:

On Wed, 13 Aug 2003 15:08:25 +0100, Richard C. Ferryman
wrote:

I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

Are you sure it's only in data mode? And are you sure it's RF getting
in? I'm asking because data is more sensitive to frequency variations
than most other modes.

There is a known problem with the VCO in this radio. Contamination of
a conformal coating designed to protect the components from humidity
is actually hygroscopic. The fix is to remove the coating and replace
it with hot-melt glue.

Any Kenwood warranty station will perform this mod under warranty on
any TS-440, regardless of whether you were the original purchaser (or
they used to... I can't speak for Kenwood).


73 de Leigh W3NLB

Richard C. Ferryman wrote in message . ..
I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

What kind of antenna and feedline are you using? MK

Richard C. Ferryman wrote in message . ..
I have been struggling for some time to get RF out of the TX audio on
a TS-440SAT when in data mode. I have ferrite blocks everywhere;
power lead, 13 pin audio lead, aerial feeder, data control cable.
Sometimes I seem to cure it then it returns. Checked every grounding
screw in the rig, checked all internal connectors. Fitted isolation
transformers on audio. It stillcomes back. Does anyone know where
the weakness is in this rig?
Richard G4BBH

What kind of antenna and feedline are you using? MK

I just disconnected every multi-pin connector in the rig that carries
audio or rf and wiped the pins and applied some 'switch cleaner'
lubricant. I also removed several screws around chassis components
and antenna connector and cleaned the mating surfaces with a glass
fibre brush, wiped with same lubricant and refitted screws. The rig
is stable again. Seems that the TS-440 must have some horrendous rf
curents circulating around the chassis that can't tolerate a few
milliohms of contact resistance. Now we'll see how long it stays
stable!

Oh for a solid cast aluminium chassis.

73 de Richard G4BBH