-----Original Message----- From: ic7000@yahoogroups.com On Behalf Of pjdemas Sent: 28 July 2006 08:09 To: ic7000@yahoogroups.com Subject: [IC-7000] Transient SWR reading on SSB I am driving a small solid state amp with the IC-7000 on SSB with the drive set to about 15% (~15 watts). Upon keying the microphone, I intermittently get a transient SWR of full scale that then drops to near 1:1 (Antenna is tuned with a transmatch). Has anyone else experienced the high transient SWR indication when running the IC-7000 at low power. Maybe it is an erroneous reading when using at low power? Thanks for your inputs Pete - W2PJ =================================================================== =================================================================== Transient SWR reading on SSB Posted by: "Paul Marbourg" zborg@comcast.net zborg2001 Date: Fri Jul 28, 2006 12:43 pm (PDT) Which brings up an important consideration for owners of the 7000 who use it to drive amps which are not designed for QSK service. The IC-7000 has NO provision for setting a delay between PPT activation and putting RF down the coax, unlike my trusty IC-756 P2. I drive a Metron MA1000b solid state amp in my truck with the 7000. When I first obtained the 7000 in December of 2005, I poured over the owner's manual to try and find the menu to set the "delay" function. Although there is a menu to set the attack constant for ramp-up of the first CW dit or dah, there is NO way (ie: menu set up routine) to enter a delay constant to allow relays to settle from switching bounce before they get hit with an RF pulse from the exciter. Perhaps Icom figured most mobile operators would not operate their new 7000 xcvr with an amplifier when mobile? So far, since I use SSB primarily when mobile, this has not been an issue for me. The TS-50 the 7000 replaced did have a delay function available for driving non-QSK amplifiers. 73, Paul WN7T =================================================================== Transient SWR reading on SSB Posted by: "pjdemas" pdemas@twcny.rr.com pjdemas Date: Fri Jul 28, 2006 1:06 pm (PDT) If Paul WN7T and Adam VA7OJ are correct, that the indication of high SWR is due to open amplfier TR switching delay, the next questions are: 1) At low drive (~15 watts) will this brief transient ("open circuit") into the solid state amplfier damage the finals on the IC-7000? 2) If there is risk of long term damage, any suggestions on how to resolve? My solid state amp is an RM Italy HLA-300V. Thanks again for your inputs. Pete - W2PJ =================================================================== Transient SWR reading on SSB Posted by: "Adam Farson" farson@shaw.ca va7oj Date: Fri Jul 28, 2006 4:08 pm (PDT) Hi Pete, Assuming (and hoping) that I was right, the short open interval at 15W drive should not do any harm. It seems, though, that the amplifier's input relay is a bit slow. As I recall, the radio will extend a ground on the HSEND line a few msec. before applying RF power, so as to avoid "hot-switching". If you wish to look further into this, you could hook up a dual-trace oscilloscope to the HSEND line and (via an RF sampler) to the amplifier's RF input. Cheers for now, 73, Adam VA7OJ/AB4OJ =================================================================== Transient SWR reading on SSB Posted by: "Phil Salas" ad5x@arrl.net phil_ad5x Date: Sat Jul 29, 2006 5:05 am (PDT) Yes, this is the problem - the lack of delay from the HSEND output to TX enable. It is not really a problem with SSB if you are using the HSEND output to key the amp, though you could run into this problem in SSB if you are using RF sensing/switching in the amp. It is definately an issue with CW. Most amp relays take about 15ms to operate. I have a Yaseu MKV, and IC-706MKIIG, and a IC-7000 that I've used to drive my Ameritron ALS-600. The MKV has a delay setting. Its default was 5ms and I had the same problem. I changed it to 20ms and it works great. For the IC-706/7000, I modified an Ameritron ARB-704 by adding an SPST switch to ground on the HSEND input into the ARB- 704. Now I leave BRK off, and enable the transmitter manually with this switch for CW operation (which also puts the amp on-line). Phil - AD5X =================================================================== Power on Self Test Anomoly Posted by: "Mike Congleton" mcongleton@sbcglobal.net kd9ck Date: Fri Jul 28, 2006 12:43 pm (PDT) Hi I assume by power on self test you're referring to the display of Power Setting, Time Out and Call when the unit is switched on. I had a problem with my '7000 some time ago where these items would not show on power up, nor would the rig shut off in the prescribed time limit. Menu settings were all set to display these items and turn the radio off in 90 min. I found the problem to be the monoral plug I had in the key jack (I use a bug). The radio would not key up in CW (with the key open) and functioned in the CW mode just fine, so I figured that it was ok to do this. Wrong! After playing around and resetting the radio 10 or 15 times I finally stumbled on the problem. Replacing the mono plug with a stereo corrected all the problems. Mike KD9CK =================================================================== Power on Self Test Anomoly (Resolved?) Posted by: "pjdemas" pdemas@twcny.rr.com pjdemas Date: Fri Jul 28, 2006 12:53 pm (PDT) Replacing the mono plug with a stereo corrected all the problems. Mike KD9CK ------------------ Great idea Mike. I think you have got the solution. I know I am using a mono 1/4 inch plug for my bug as well. Know bug in the mobile, that why the test works just fine. I will check it out and report findings. Thanks for your insight and help. (I did not want to send it in for service if there was not anything really wrong!) Pete - W2PJ =================================================================== =================================================================== Power on Self Test Anomoly (Resolved!!) Posted by: "pjdemas" pdemas@twcny.rr.com pjdemas Date: Fri Jul 28, 2006 8:11 pm (PDT) That was it Mike. I was using a Mono 1/4" plug for my Bug. When removed from the IC-7000, power on self test functioned correctly. Thanks for the support! Pete - W2PJ =================================================================== Transient SWR reading on SSB Posted by: "Phil Salas" ad5x@arrl.net phil_ad5x Date: Sun Jul 30, 2006 5:25 am (PDT) --- In ic7000@yahoogroups.com, "pjdemas" wrote: > I am driving a small solid state amp with the IC-7000 on SSB with the > drive set to about 15% (~15 watts). Upon keying the microphone, I > intermittently get a transient SWR of full scale that then drops to > near 1:1 (Antenna is tuned with a transmatch). Has anyone else > experienced the high transient SWR indication when running the IC-7000 > at low power. Maybe it is an erroneous reading when using at low power? > > Thanks for your inputs > Pete - W2PJ > I bet you are using RF sensing in the amplifier to enable it. You shouldn't have a problem if you use the HSEND output with PTT to key the amplifier (with the appropriate interface of course). This morning I made a bunch of measurements using CW so I could accurately see the starting waveform when triggering my 'scope with the HSEND output. First of all, I never really see a problem on the first dit when using my IC-706MKIIG driving my ALS-600 amplifier (using the HSEND output to key the amplifier), but I do get a SWR "kick" with the IC-7000 under the same conditions. On my IC-706MKIIG, the time between HSEND going to ground, and RF output is 13ms for the RF starting to come up, and 15.5ms for full RF power. On the IC-7000, I measured 8ms for RF starting to come up, and 10.5ms for full power. So when using external amplifiers controlled by the HSEND output, you will probably have a momentary SWR/ALC kick on that first "dit" with the IC-7000 since a typical open frame relay requires 10-20ms to pull-in. I measured 12-15ms for the relay to pull in on my Ameritron ALS-600. When RF sensing is used, you'll probably see this issue on most any radio, as you have to have RF power present for the amp to sense before it starts enabling the T/R relay in the amp. So when RF is present and the relay starts to pull-in on the amplifier, there will probably be a momentary open circuit to the RF output of your radio during the relay switching time. This won't be as consistant with SSB as it will be with CW, depending on the voice characteristics at the time switching is occurring. Phil - AD5X =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== =================================================================== ===================================================================