RF feedback in 5000A
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Posted Saturday, September 10, 2011 7:41 PM
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Hi to all,

I'm a new owner - 5000A, Windows 7 32, Heil headset. Old Yaesu FL 7000 solid state linear. Excellent ground connection.

Everything worked straight from the box, and the linear loaded up better than any exciter used before.

But got this amazing feedback at any SSB setting above 20 watt output. Others have commented on this before in the forum, with several solutions suggested. I tried them all including ferrites everywhere - no good.

But then I pulled out the PTT jack from the microphone plug connection, and the motorboating went away! Now I have my PTT in the separate jack on the back panel, and it works like a charm up to full output.

A simple story - fairly obvious I guess, but it might help others in the same situation.

Ian Sykes VK1JY

Ian, VK1JY

Post #4842
Posted Monday, September 12, 2011 8:59 PM
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Just curious as I and still looking very hard at going the flex route

What are you using for a microphone and what type of cable is it hooked to?
Post #4855
Posted Tuesday, September 20, 2011 4:45 AM
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Hi I had a similar experience, first I made sure that the front panel mic input was correctly grounded then I put ferrites on all inputs to the 5K, this solved most of the problems. However the most significant change occurred when I changed my annenta, an "Inverted L"  which is unbalanced, to an OCF dipole. This I assume eliminated the RF entering the shack due to poor grounding an my inverted L. I am now problem free
Post #4891
Posted Wednesday, September 21, 2011 8:53 PM
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I had RF feedback issues a while back also.  I did a lot of things related to best practices on grounding, etc. but the real fix came when I began using the rear-panel balanced audio input instead of the front panel jack.  I am using a Heil PR-40 microphone, so this was an easy task after a visit to my local Radio Shack to get the proper cable with XLR connectors.   An earlier poster noted that moving the microphone PTT (in my case a Heil hand PTT) to the rear also helped;  it did in my case also.  With everything disconnected from the front panel mike jack, all is well. 
Post #4915
Posted Thursday, September 29, 2011 11:41 AM
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Ian,

One thing that you might want to verify is the Yaseu adapter for the headset.   Some of the adapters are wired with the shields going to only Pin7 (Mic -   of the mic connector instead of Pin5  (chassis ground)  .  Seems the old FT1000 was wired to pin7,  newer radios wired to Pin 5  for chassis..  This oversite can cause RF directly into the preamp of the mic -   .  If the shields are verified to be gong to Pin5,  then maybe a ferrite with the mic looped through as close to the mic connector as possible can help..  Also the same on the FW connector.       

One suggestion is to try just about any old dynamic mic into the Balanced input on the rear,  maybe an old PA or stage mic with a 1/4 connector.   Change the Mixer menu to Balanced..   Just to see if the RF goes away. 

Also if the RF is worse on certain bands or antennas,  the real cause might be common mode RF.   Add a common mode choke,  and/or change the length of your feedline

Maybe some of this will help

73,

Dudley

FlexRadio Systems Support
512-535-4713, Option 2
http://helpdesk.flexradio.com

Post #4965
Posted Thursday, October 6, 2011 11:28 PM
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One suggestion is to try just about any old dynamic mic into the Balanced input on the rear, maybe an old PA or stage mic with a 1/4 connector. Change the Mixer menu to Balanced.. Just to see if the RF goes away.


yeah.... it is a good idea...





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Post #4996
Posted Thursday, October 13, 2011 6:45 AM
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I was never able to full get rid of RF feedback until I connected both grounds in the mic connector body (on the mic side), i.e. chassis ground.  This is easily done by using a #22 bare wire from pin 5 to pin 7, and then extending the wire back along the mic cord.  Remove the screws from the clamp on the mic backshell, mount it on the mic connector, then wrap the #22 wire around one of the clamp screws as you replace the clamp, and cut off the excess.  No problems since.

Clyde Washburn, K2UE
Post #5016
Posted Saturday, November 12, 2011 2:14 PM
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I now have the 1500, 3000 and 5000 and the had RF feedback issues when using a Heil quiet phone headset, even with 100w out or less. With a Yaesu hand mic I can ran full legal without any issue. Teh quiet phone does not have any shielding so perhaps this is the problem but it is certainly worht trying to remove all you can and testing with minimal connections and work back plugging in one item at a time to find where the issue is.

Justin


Justin G0KSC
www.InnovAntennas.com
Post #5105
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