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Messages - G3UEG

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General discussion forum / Re: RS232 port isolator help
« on: 2010-10-19, 12:25:26 »
Hi Stan,

Thanks for the link.  It looks like just what I need. I will drop them an email.

Dave, G3UEG

General discussion forum / RS232 port isolator help
« on: 2010-10-18, 21:30:57 »
In another thread I said I was going to try an RS232 port isolator to try to cure my RFI problems with TS-480 and SPE amp.

After a week of searching and discussions with suppliers I have been unable to find anything suitable.  I need to isolate TXD, RXD and also the DTR line (pin4) which is used for turning the amp on/off with a 200m/s pulse.

Many products only isolate TXD/RXD.  Many products derive their power from the RS232 port itself, which is not available from the RRC or the SPE amp.  I have found a product that has provision for an external power supply, but it only isolates the RTS/CTS in addition to the TXD/RXD.  Another product allows any 2 additional handshaking lines to be isolated (selection by jumpering) but it has to be self powered.

1) Does anyone have details of a product that meets the specification?

2) This might be a stupid suggestion but would it be possible to take the DTR line from the RRC and route it through either the RTS or CTS circuit of an isolator and then route it back to the DTR line on the SPE amp?

3) Might it be possible to design and build ones own isolator - any ideas?

Dave, G3UEG

I have started a new thread as the previous "TS480 RFI - more information" has become rather long.

If anyone has TS480 RFI problems -  please see the previous thread before doing anything else and resolve any confusion with the ground wires, and deal with that first.

After doing the ground wire strapping changes I have been able to run 100w barefoot on 80m thru 10m with no problem including the use of the speech processor.

Last week I re-connected the SPE Expert amp. Using it locally (mic plugged direct into head unit) everything worked perfectly.  However, trying again to use it today remotely with someone listening a few miles away from the remote site, there are serious problems. 

1) Running the same 100w barefoot with the amp in circuit (but in standby), I am getting a regular pulsing about 2 pulses per second when pressing the PTT but not speaking, I can see around 3w being registered on the amp with occasional 20w peaks.  when speaking, the pulsing is still there underneath the audio.  This is the same on both the 80/40 dipole and the separate 20m dipole.  This is without the speech processor,  if I enable the processor it is totally un-usable.

2) On 20m I can run 400w CW without problem

3) On 40m if I send very slow dashes, the received signal a few miles away is varying by over 10db.

I believe someone else reported that an Alpha amp worked perfectly well, but when swapped for the SPE amp, he had a lot of problems.  I would like to know what actions were taken and whether a cure was ever found?

I am suspecting the RS232 lead.  Does anyone have experience of RS232 isolators and whether one might help?

Dave, G3UEG

Hi Guy,

Thanks for the info..

Dave, G3UEG


Thanks for replying..

In my documentation Pin7 is ground and Pin5 is CTS  was your reply a typo, or is the RRC wiring different?

Dave, G3UEG

Because of ongoing RFI problems I want to replace the RS232 cable between the RRC and the SPE Expert amp with a screened lead.

1) Question for Mike..
  Is the shield of the female DB9 connector of COM1 connected internally to the ground pin 7?  If not what is it connected to?

2) How do I connect the screen of the 4-core cable, there is no obvious connection point on either the DB9 male plug itself or the metal shell in which it is fitted? and do I make this connection at both ends or just one? and if just one which end?

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-09-09, 12:23:30 »
Hi Mike,

Thank you for the clear answers.

I will have one more attempt to get it working before I give up..

I think I shall strip everything down and start again.  Of the things you have mentioned, I shall
1)  Renew the jumpers carefully
2)  Remove the SPE amp connections inc the RS232
3)  Increase the mic levels through the system and reduce the mic gain.
4)  try placing everything on a large flat aluminium earth plate.

Finally can anyone confirm whether there is anything at the control end that can be done to mitigate the problems (other than adjusting the gains as suggested above)

Can anyone explain why if it is a problem with the TS-480, why the problem does not show (even at max power with amp)  when using the standard hand mic or a Heil headset direct into the rig when operating it locally??

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-09-08, 17:07:32 »
MIKE - Please help..

There are a significant number of us having the same problem. 

A number of questions have been asked to which no answers have been forthcoming,  I will summarise them here and would be grateful for some answers.

1)  What is the spec of the jumper wires.  I want to redo the jumpers just in case there is a bad connection.  The wires bend very easily and are difficult to re-use once they are bent?

2)  Would doing the mic gain mod help overcome the problems we are having?

3)  Would it help to put the RRC in a screened box?

4) Would it help to put a 1:1 decoupling transformer in the mic connection between the RRC and Rig?

5)  There are a number of errors and inconsistencies in the Kenwood documentation for the RJ45 mic connector 
    a) pin numbering is non-conventional
    b) the mic ground and system ground pins are swapped round in the User Manual
Can you confirm that the wiring schematic for the RJ45 lead from RRC to Rig,   and the jumper wiring diagrams are correct bearing in mind these errors.

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-08-23, 15:59:12 »
Thanks for all the comments..

I don't get any problems when operating seriously in contests when I am actually at the remote site operating in person and running things at max!!
I have acquired an RF clip-on meter and cannot detect any RF current on the 50% of the leads I checked..
(I will re-test the meter itself!!!)

The codec input pre-amp has been switched off from very early on.

Could you describe more fully what you had to do to your SPE amp to "tame" it...   I have wound the mains cable abt 6 turns through an FT240-43 core at the amp end, plus a couple of clip-on cores at the other end..  I have also wound the PTT lead many times through a smaller core.  I have several clip-on cores on the RS232 lead.  I have put an RF common mode choke in the coax feed to the external antenna switch.

I went to the site yesterday again and as well as working on the amp as described above.. I have changed some of the ferrites of unknown spec to ones with Type 31 ferrite, which has higher loss than type 43.
The short RJ12 lead has three cores.
The Aux/Mic lead has 9 cores
The dc supply is wound many times round a torroid.
There are several clip-on ferrites on the ethernet cable and RS232 cable.

All of this made a very slight improvement..  I can now TX 100w barefoot with the processor on, and about 200w with the processor off.. both of these about twice what they were before..

Any thoughts whether there would be any point putting the radio RRC inside a metal box??

That is now 5 trips and 1000Kms to try to solve this problem......

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-08-21, 13:39:32 »
Hi Steve,

Useful info from the test.  I realize it would be pain, but two more tests..

1) TS-480 and RRCV1 and
2) IC706 with RRCV2

would be **VERRRRY** interesting.  I would be willing to help if you would like..

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-08-16, 15:29:59 »
Hi Walt,

Thanks for the suggestion, but the pre-amp has been off from the beginning.  Also I have reduced the codec input gain down from the recommended level to try and tame it further.

Are you using the RRC V2? and have you done the op-amp mod?

Dave, G3UEG

General discussion forum / Re: TS-480 RFI - more information
« on: 2010-08-15, 21:45:19 »
Hi Steve,

I would be very interested in the result of your proposed test with the IC706, are you planning to try it with the V1 or V2 RRC?

I hope Mike can suggest the correct course of action re the Op-amp mod..

Dave, G3UEG

General discussion forum / TS-480 RFI - more information
« on: 2010-08-14, 22:20:36 »
The receive side of my system has been superb, but I have had serious problems with RFI when transmitting and have had to install a large number of ferrites to get to the stage of being able to transmit at the 100w level.

My approach has been to back off the various gains both in the radio as well as in the RRCs, so there is virtually no ALC being triggered, with just one led occasionally 

The interesting discovery is that most of the problem is when using the internal speech processor.  Testing has been on 80m as this is the only band I can hear myself on from my home operating location..  (100Km away)

Having got the SPE amplifier working I have discovered the following:-
1)  I can transmit 400w on CW
2)  I can transmit 400w on SSB as long as the PROCESSOR IS OFF
3)  With the processor on (even with low levels of processing) I cannot transmit more than about 50w

The RFI effect I am getting is a continuous "clicking" at about 2 per second which generates significant RF output. This happens as soon as I press the PTT and before I start speaking, and continues when I start speaking.

Does anyone have any ideas what I can do to solve this problem??
I have wondered about cutting the audio (RJ45 cable) and putting a 1:1 transformer in the mic circuit
Am not sure whether I should do anything else on the other wires.

Question for Mike..
What effect on the RRC performance is there by further reducing the Codec Input gain??

Dave, G3UEG

General discussion forum / Re: SPE Expert 1K on COM1
« on: 2010-08-14, 21:29:52 »
I now have the SPE amp working..  the problem was that the cable at the radio end had been made correctly, but labelled wrongly (both connectors are the same gender).

So once I turned it round it is working correctly with the settings taken from the latest manual.

Dave, G3UEG

General discussion forum / Re: SPE Expert 1K on COM1
« on: 2010-08-09, 20:57:25 »
Hi Guy,

Thanks,  the cables were built to the spec you detailed (also as in the pdf doc on the website)..  I have checked the home (control) cable but as I said I have to do a 200Km round trip to check (again) the remote (radio) cable..  I plan to do this later this week.

It is the serial settings that I would like to have confirmation of from someone who has it working...  as there are a number of different variants that have been published,  or commented on in this forum.

Dave, G3UEG

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