Keying Expert 1.5K-FA amp

Ed K5YZW

After working flawlessly for over a year, my Flex 6700 stopped keying the Expert amp which is through TX1.  My TX profile has not changed and has RCA all the TX1 boxes checked.  The cable was made by Dan Tassell.  Any ideas would be much appreciated.

Steven WA8Y

Is the cable still engaged in TX1 RCA socket? Do you have contact closer at TX1?

Ed K5YZW

Thanks Steven.  Yes the cable is in TX1 RCA socket. In fact,  I changed the TX profile to TX2 and TX3 and moved the cable to those RCA jacks and it still doesn't work.

Patrick

Call or E-mail Dan, and try power cycling the amp to reset it’s internal devices....if you have not already done so...

Ed K5YZW

Thanks Pat. I talked to Dan and he didn’t have any suggestions other than something wrong with the TX Profile. I did cycle power on Expert but no change. When this first happened early this week, rebooting everything fixed it but not now.

Brian Morgan VK7RR

Larry _ NY8T

David - KO1C

I've had TX profiles go "bad" and once I replaced them, all was well again. Good luck!

DV

Mark_WS7M

Ed K5YZW

Thank you all for the help.  I tried all suggested tests.  Everything passes--the wiring is good and the Flex is sending the TX1 signal which apparently is being received by the Expert amp.  For some reason the Expert is not responding.  I have emailed Bob with Expert Amplifiers and will see what he thinks the problem might be. The FlexRadio Community is great!

Mark_WS7M

Ed, Bob just repaired my poor lightning struck 2K FA in record time so he will take good care of you.

But I am curious.  You say you tried all the tests and I believe you.  Did you try shorting the RCA input to the SPE amp?  Does it go into transmit or not?

Ed K5YZW

Bob, Dan Tassell who makes cables for Bob told me that the Expert uses a transistor and not a relay so shorting the RCA input would not work.  Is there another way to test it?

Clay N9IO

Ed K5YZW

I shorted the RCA input RY1 and the red transmit light came on.  So it appears that the Flex is not doing its job.  What should I try?

Craig_KØCF

Mark_WS7M

Yes Ed, this is a process of checking each piece.  If I'm not mistaken:

1) You have confirmed that if you put your Flex in tranmit that you see continuity across the Flex RCA TX1 output right?  The best way to test this is to sacrifice a known good stereo RCA cable.  I have about 10,000 of these laying around from various VCRS, TVs etc over the years.   Anyway you but the cable like 3 inches from the RCA plug.  You will find a shield and a center conductor.   Plug the RCA plug into the Flex RCA port.  Put your volt meter leads on the shield and center conductor you just cut.   Now put the flex in tranmit.   1 W on tune should do it.   Does the meter show continuity?  Does it beep?   If so the Flex is closing the connection.

2) You claim you just did this.  But if you take the same sacrificed RCA cable and plug it into the RCA input on the SPE amp and short the center and shield together the SPE should go into transmit mode.  Red LED and display should change.

If 1 and 2 are good and you see continuity and SPE goes into transmit then your RCA cable going between them has to be bad.

Clay N9IO

Ed,
Be sure to go into TX Band Settings and confirm you have TX1 TX2 and TX3 checked on for each of the bands al well.

Ed K5YZW

Thank you all for the help. I did verify that the SPE was being keyed but there was no power output.  I got on the phone with Bob Hardie, the U.S. rep dealer for SPE Expert amps, and he took me through some checks and determined that it looks like a MOSFET failure.  So I am boxing it up to send to him.  Thanks again.  I will post the outcome.  73, Ed K5YZW

Clay N9IO

Sorry to hear Ed wish it were a simple fix for you.
Good luck.

Clay N9IO

Ed K5YZW

Clay I doubled checked the TX1,2 and 3 boxes are checked in the TXBand Settings.  I also tested the TC1, 2 and 3 sockets when transmitting and they registered on the ohm meter.  

EA4GLI

This happened to me on the 1.5k.
The explanation from SPE Italy was that the relay for band change got "stuck" and when I TX on a different band it blew my finals [sic]. I had to send it to Italy and it got repaired under warranty, but I had to pay shipping both ways and wait for 3 months!!
Hopefuly you get a better turn around with the USA SPE Service.

Ed K5YZW

At least SPE made good on the warranty. Mine is still under warranty so we will see. Bob Hardie said he could turn it around fairly quickly as there are 4 ahead of me.

Mark_WS7M

Good to hear you figured something out.

Bob just repaired my lightning struck SPE 2K FA very quickly.

Ed K5YZW

Glad to hear that. Bob is very responsive. Did the lightening do a lot of damage?

Ed K5YZW

Again I appreciate all the help.  I got my SPE back from Bob.  He said I had over-driven it too many times.  I have tried to be very careful to not over-drive the amp but it has happened, usually a result of a mistake, not pushing it.  Bob strongly recommends using ALC with the Flex.  Does anybody do that and how do I set it up?

Bob Needleman

Ed - all solid state amps running MOSFETs are much more sensitive to over-driving vs. tube amps. So you must insure you don't over drive them, and best way to do that is using ALC. The procedure for proper adjustment of the ALC should be in your amp's manual, but the basic idea is to set the ALC level to the point where your rated PO Max (eg. 1.5 KW) just drops off which will insure you never drive it beyond that point. The other way to do that is by setting the Max TX PO on the exciter (ie. the Flex) to the TX PO setting that will give you slightly lower PO from the amp (or even a bit lower to play safe). Remember that your signal really isn't going to be received much stronger if you go from around 1KW to 1.5KW, so keeping the power down under the max. rating of the amp will protect those expensive MOSET finals.

Bob K3AC

KD0RC

Hi Ed, I discovered DDUtil when I was researching the Elecraft KPA500. It lets me set max RF out of the Flex per band and op/stdby. So for example, on 20 M, I can have a standby amount of 100 and an operate amount of 24. This has kept me from accidentally transmitting 100 W into the input of the amp. This utility also lets me control the amp and tuner from the computer. It also "follows" the Flex frequency, so tuner and amp band settings happen automagically without relying on RF sensing. It is cool (and reassuring) to hear the tuner relays click as I tune the Flex up and down the band or if I change bands. You might want to check into it to see if it works for your amp. 73, Len, KD0RC

KD0RC

P.S. I also set up a .bat file that starts SSDR, and then opens DDUtil, my logger and SliceMaster. That way I won't forget DDUtil, defeating the whole purpose for having it... Len

DV

Patrick