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First day with OMNI VII on the air 03.03.2007
DJ0IP (dj0ip) Yesterday (2007-02-28) I received an OMNI VII to “play with” and I want to report my results. This time even Carsten called me and asked me if I had my RosaRot Ten-Tec Brille on! I only reported what I heard with this radio.
 OK, it is no secret that I like Ten-Tec, and I am probably the only person in the world who got an OMNI VII for free just to play with, but I only got it for one week.  I have to give it back.  I do not get to keep it!!!  I asked Jack if I could try it in Europe before I move back to the states.

But I assure you I have also had some real heated discussions with Ten-Tec’s president (Jack) in the past about a couple of Ten-Tec radios which I did not like at all.  One of them he personally designed and it was his favorite radio (the Scout).   Ten-Tec builds good stuff and not so good stuff, just like everybody else (including Brennholz!).

The following report is my first day’s experience with the new OMNI VII:

Yesterday afternoon the OMNI VII (OM7) arrived.

My XYL had committed me to being the designated driver for her and her girlfriends’ “night out”, so that highly limited my time for playing with the new OMNI.  It also kept me on mineral water, even though we were in a “Local” which served Augustiner Edelstoff vom Faß !!!  Man, that hurt!

I currently only have a 40m vertical (full size) and no other rigs to compare the OM7 to (except a 20+ year old Argonaut 515 without any narrow filters).  Next weekend I will take the OM7 to Toffy’s contest station, DL1A (DJ6ZM) on the west side of Munich.  There we have beams on all bands except 160.  For comparing we also have an FT-1000 MK5 FD, FT-2000, K2, and Orion.

Being a 40m fanatic and living in Europe, I have become accustom to disappointments when testing new rigs.

We have a multitude of shortwave broadcast stations which play havoc with most receivers’ front ends, beginning in the early evening, getting worse at dusk, then slowly getting better towards midnight.  Hey, I don’t have to tell you guys that – you live here.  I wrote that for the Ami’s (hi).  Attenuation in the front end of the RX helps, but it also attenuates the desired signal.  This can be significant if the desired signal is only S1 or S2.  That’s why the use of an external preselector is popular here.

Although I had no other “good” radios here to compare it to, I have recently owned (within the last 2 years) two Orions, two K2’s, an Omni VI+, and a TS-480 (ausnahmsweise, ein gute Brennholy),  and tried a TS-850 but it fell over with intermod problems, since it had no preselector connected.  The comparisons shown below are based on my memory, not on side by side comparison, since I have sold all of the other rigs.

So please take my info with a grain of salt, your mileage may vary, etc. -

Testing was done last night from 5pm until 6pm local, >from midnight until 1am local, and again from 7:30 until 8:30 local this morning.

I was mostly just receiving and trying hard to find intermodulation problems on the OM7.

The external preselector connected to the OMNI VII is a home brew bandpass filter (not tunable), similar to the famous Braun preselectors, but not quite as good.  It is built using Ringkern coils.

Results:

  • There was no blanket of noise across the 40m band (even without the external preselector), like there are with so many other rigs.  Even switching the preamp on did not produce this adverse effect.  THIS IS SIGNIFICANT!    For comparison, on this (vertical) antenna:
    • The newest K2 (S/N 4606) had about an S1 to S2 blanket of noise across the entire band with preamp on.  It was generally clean without the preamp, except for peak problem times (dusk) where the attenuator or the external preselector eliminated the intermod entirely.
    • The TS-480 SAT had about an S5 blanket of noise across the entire band with preamp on.  With the AIP (preamp off) the radio was also pretty clean, except for peak problem times (dusk) where I needed the attenuator.  I never tried the preselector on this rig.  Of course the attenuator also attenuates the desired signal but not as much as it attenuates the intermod.
    • The OMNI VI+ was generally clean with perhaps an S1 blanket of noise at peak problem times.  The attenuator, but better yet, the external preselector always eliminated it.
    • The ORION was always clean in all circumstances on my antenna, and on DJ6ZM’s 3-el beam at 100 ft., exhibits similar light intermod problems to what I experienced with the OMNI VII using my vertical. These are completely eliminated (on the ORION) by turning back the RF gain to 95%.
  • OMNI VII Intermod:  There were a few instances where there was a strange carrier (obviously intermod) on the order of S2 to S5, but usually I could eliminate it with 6dB (occasionally 12 dB) of attenuation.  Of course switching the external preselector in also eliminated it without reducing the strength of the desired signal.  These carriers would go on and off, and I have no idea what was causing them, but it was clearly intermod because just 6dB of attenuation would drop it several S-Units.  Something somewhere was mixing with something else.  There were 4 or 5 frequencies where I experienced this.  The rest of 40m was clean, even with preamp switched on.  DO NOT INTERPRET THIS TO BE BAD.  IT IS EXCELLENT.  Most receivers are much worse under these conditions.
  • There was no pumping on strong signals like we experienced on the FT-2000.  To be fair, that was on DJ6ZM’s beam and I haven’t tried the OM7 yet on that antenna (update next week).
  • While I was on 40m, Sigi (DL6QW) was visiting my neighbor ham (Freddy) and was on 160m trying to work the VK9NDX-pedition.  He was running a healthy kilowatt (using my old linear amplifier) and our two antennas are only about 200 meters apart.  When he transmitted, the noise level would go up about an S unit or 2, but modulated according to his SSB signal or to the cw signal.  The noise sounded a bit raspy.  The preselector eliminated this.  For comparison:
    • The TS-480 had about an S-8 increase in noise under these conditions (in the past of course).  Freddy is often on SSB on the weekends while I am (mostly listening) on 40 cw.
    • I never noticed this on the OMNI VI (over a period of 4 or 5 years) unless Freddy was on the same band as I was.  Often he was operating SSB while I was on CW on the same band (40m).  In that case I used my home-brew (DL7AV) tunable preselector which pretty much eliminated the problem.
  • This morning I heard VK9NDX and worked them first call (cw), barefoot, through a mini pileup.   Like ALL other Ten-Tecs, the OM7 has beautiful QSK.
  • And to my pleasant surprise, the old Argonaut 515 could hear everything the OMNI VII could, unless it was disturbed by strong QRM.  However I had to back off the 515’s RF gain and play with its own built-in preselector to avoid intermod.

Bottom Line:  This radio is a true Ten-Tec!

There has been a lot of speculation on the (Ten-Tec) reflector as to whether the term “Distributed Roofing Filters” is real value-add or just marketing hype.  Coupled with careful management of amplification (signal strength) from the antenna input through to the second mixer, it becomes very effective, but one needs to understand this.  It’s a slightly different approach.  It clearly gets the job done, but I think Ten-Tec will have some missionary work ahead of them.

Their main problem is, they did too good of a job in selling the industry on the concept of “roofing filter” when they brought out the ORION. 

For those of you not following the Ten-Tec reflector, here is the scoop.  Ten-Tec has only one roofing “normal” filter in the OM7 and it is 20 kHz WIDE at 70 MHz.  It then mixes to 455 kHz where it has Collins mechanical filters which are called “distributed roofing filters”.  This sounds like the old way of doing things (before the term roofing filter became popular).  Basically it is, except the overall stage gain has been kept such that it is unity from the antenna through to the 2nd mixer. This enables placing the roofing filters at 455 kHz instead of at 70 MHz.  We were all very skeptical about this, but based on what I have heard on the bands, it seems to work quite well.

Next update will be after testing on “real antennas” at DL1A.

Toffy (DJ6ZM) and I will do that tomorrow night.

For me the big test is not really how the OMNI VII compares to the ORION, but rather how it compares to the FT-2000 because these two radios are in the same price class.

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