Hi Chet,
Before we start, a disclaimer: I still have my MP, maybe I'm a radio
hoarder. I do have a 75A3 and a Johnson Ranger and Courier and an FT 101ZD.
The only long used radios I don't still have are my SB300 and SB400, and I
wish I hadn't sold those. So my MP bashing is technical and proven, and I
still love my MP enough to keep it. I hope its feelings aren't hurt by lack
of use since the K3.
Back in the heyday of FT1000MP, when that was one of the best contest
radios available (IF you fixed the clicks), I used to take mine out to N4AF
for the multi-op DX wars as NY4A. I used my MP on 40 meters out there,
which at that time was listening to a 5 element quad stretched out on 190
feet of catenary between towers, end-on to 45 degrees. Loads of incoming RF
off the big quad.
With the MP, the bottom layer of signals was usually all the DL/OK basement
noodle antenna QRP signals. When the K3 showed up, the DL/OK basement
noodle QRP crowd became essentially workable and the new bottom layer of
signals was all the European Russians running 100 watts to a dipole up 20
feet on the southeast side of a big hill. Goaded by the astonishing
improvement, some K3 to MP comparisons showed very convincingly that what
we always thought was the bottom atmospheric level in the MP was actually
being generated IN the MP, because it was absent in the K3. A/B there, not
there, couldn't possibly be that much. Repeat test 50 times at least,
there, not there. After a half hour of doing the same test over and over,
with exact same result over and over, "Gee, guess the K3 has improved a
lot."
N4AF switched to K3's, and very quickly all the "drug-in-with" radios were
K3's, except for one Orion I. Within a couple years, 11 FT1000MP's in the
NY4A crowd morphed into 14 K3's.
There definitely WERE some separate sensitivity issues in the MP, a bunch
caused by too much RF coming in the line in RX mode. Your deaf as a
door-nail kind of spot reports screams as a repeat of one of those MP
insensitivities.
There is a little itty-bitty choke in the RX on TX antenna circuit, which
can burn but NOT GO OPEN. It goes resistive because what's left over after
the wire burn is still conductive. The DEGREE of resistive is unpredictable
and can change. I know because over the years I've replaced a half dozen of
them. You can find them in the schematic. The quick no-solder,
no-disassembly fix to get around the problem and listen on the TX antenna
with full sensitivity is 1) on the back panel patch the RX OUT RCA jack
(connected to TX ant when not transmitting) to RX IN RCA jack right next to
it, and 2) on the front panel use ANT RX. The coil is not in the RX ANT
circuit. If you suddenly hear better, you know what to do. If you never do
SO2R or operate the MP at a multi transmitter site, you maybe don't need
the choke. The K3 has a COR relay for this.
We always replaced the @%#@^&!! chokes because we were afraid to run the
MPs at the multi site without those as protection for some cross-antenna
backfeed we had unknowingly reintroduced.
I can't explain the MP engineering there. That's just how it is.
If you bought the MP second-hand and in its other life it was operated at
high power multi sites, it could have been that way since you had it,
therefore no suddenly worse performance as a clue to check things out.
Anyway, I would check that out before you go tearing up all your antennas.
73 & HNY all,
Guy K2AV
On Sun, Dec 30, 2018 at 8:35 PM chet moore <chetmoore@cox.net> wrote:
> Todd,
>
> Thanks for sharing. I've been following your post. I too wondered about
> sharing the radial field like you did. My situation is somewhat similar in
> that I feed a 90 foot tower which has a c31 at 95 feet and a two el xm 240
> 40m beam at 75 feet beneath it on a gate....the antennas should give me
> some top loading but it has never been modeled. Shunt wire presently comes
> down from 70 feet about 3 feet out from the tower to the base of my tower.
> The Tower(AB-105) Is guyed at 40 and 70 feet, guys are broken up with
> insulators. I have tried to find the resonant freq of the tower and at
> one
> time or another I have moved that tap from 40 feet to up 50 60 70 feet in
> 2
> foot increments. (that's a lot of climbing)and never found the sweet spot
> if there is one. I saw your post and Like you I wondered what would
> Happen if I ran an inverted L up to 90 feet. (I already had a pulley and
> rope up there) and run the tail out to the west since I seem to be "deaf"
> to
> the west and north west (and really everywhere) and would share The same
> radial field which has 2 radials that I was able to stretch out to 100
> feet
> (in a very crooked line) and a couple of others that are 60 feet and 56
> others of various lengths from 20 to 50 feet. The correct word is probably
> not "share" as only one of the antennas would be hooked to the xmtr at a
> time. My salt water swimming pool Is about 8 feet from the base of the
> tower. Not sure if the pool helps or hurts in any way. In the fall, once I
> cover the pool,I run out 30 radials of varying lengths which I have to
> roll
> back up again come spring when we uncover the pool. I remotely tune the
> tower with a motorized vacuum variable capacitor to tune the tower for
> minimum swr. I've only played with this since I saw your post. 5 years
> ago
> Before trying the shunt fed tower, I put up the inverted L with 4 buried
> radials mainly to be able get some points for PVRC in the DX contests. 160m
> has a way of hooking you in to trying to do just a little more than the
> bare
> minimum I then added 6 more radials, then a few more and then a few more
> after that. I noticed that things got better Up until I had 20 radials or
> so
> and then adding more radials didn't seem to help or hurt anything .
> Bandwidth went down at first and then like it says in the on4un book,
> leveled out. The real problem for me is RX. I have never heard a KL7 on 160
> even though guys locally 3 or 4 miles away hear and work KL7's in every
> arrl or cq 160 contest. (I'm located 7 miles off the water at Virginia
> beach) I have managed 1 KH6 QSO (could not hear either of the two I saw
> spotted last night in the stew) Things are up and down here. Stuff I don't
> expect to hear. I sometimes get, but other easier stuff I never hear.
> Example, when I was able to work the ET3 on 160 a while back. I also got
> Yemen when K1ZM was in sanaa, I got bouvet last time out, the last 2
> FT-8's but still no KL7. Never expected to work the VP6 or whatever the
> latest big dxpedition was a few weeks ago , the one that had to leave
> early due to weather. Vp6di Ducie? Xmas? Either one would have been new one
> for me on 160. I just knew I wouldn't hear them so I did not check for
> them........Until the night before they left, I turned on the rig, I was
> on 40 m and saw them spotted. Figured ok I'll waste my time and Clicked on
> the spot. I could actually hear them on my 40 m beam, switched to the
> shunt fed tower and zip, nada, nothing. Back to the 40m beam and they were
> still there. Went down to feed point and found that the dogs toy was
> entangled in the shunt feed and in trying to remove it, the dog had ripped
> the feed wire off of the top of the vacuum variable with his toy still
> attached. It was pouring rain so since this expedition was gonna be there
> 2
> more days I figured I'd fix it at first light or as soon as the rain
> stopped
> and be ready that night. I was WRONG. The weather apparently got so bad
> they left early so I never got to call them.
>
> In the Stew I tried out a couple of quick swap outs between the inverted L
> and the tower on both G4AMT & KV4FZ last night in the stew when both were
> running em and I could not discern any difference on receive between the L
> and the tower. I worked both of them with 100 watts. I called N6RK on both
> antennas. On the inverted L I got an imi, and on the shunt fed tower no
> response. Lots of qrm. n6rk was not loud but he was the ONLY w6 I heard.
> N2IC was loud from new mexico all night.
>
> When I try to call cq I can hear partial calls and I know there are
> stations
> calling me. I know I was called by an EU4, 9A2 and a TF2 last night but I
> couldn't pull any of them thru.
>
> The shunt fed tower seems to radiate pretty well on xmit but on rx its an
> alligator. I definitely get out better than I hear but its still pretty
> discouraging to call CQ and to look at dx summit and
> see.....................spots like these from the europeans
>
>
> N4FX ZZZZ ?????.
> N4FX no receiver
> N4fx don't waste your time calling, rx broken
> N4FX No ears
> N4FX Unmanned beacon station??
> N4FX Big signal does not hear
> N4fx code reader failure???
> N4FX op asleep at key???
> N4fx where is he listening?? is he even listening?
> N4FX working crossband???
>
> I have tried a 200 foot BOG which actually runs across the street and cars
> drive over it. (I roll it out after dark but not a busy street). And roll
> it
> back up when I am finished) It works pretty well sometimes but last night
> was not one of those times. tried a W2UP rotatable Loop which lost all
> directivity when I ran some radials out in its direction. A VE3DO loop (no
> joy at all)
>
> I just had my mp1000 tweaked and have a 756 pro II and don't think either
> of
> them has an rx problem.
>
> Talked to Lee K7TJR about his antennas and because my tower sits almost
> smack dab in the center of my lot he didn't seem to think it would work
> well even if
> I were to detune the tower. I'm not sure that a K9AY or SAL would work for
> the same reasons.
>
> Like you I think I will just take down the inverted L. I learned quite a
> bit from some of the comments you got. I didn't fix anything but
> definitely
> know a lot of things that won't work. It was not particularly reassuring
> that when AA1K was here last year, I asked him if he thought a choke at the
> feed point would help anything? He said he didn't think one was needed on
> a
> vertical. Then I asked what else I could do he suggested that I might want
> to consider putting up a FOR SALE sign.
>
> Thanks again for sharing your results.
>
> 73
>
>
> Chet N4FX KP4EAJ, VP2A, ZD8W, VQ9Xx, KL7AIZ, KG4ZO, N6Zo/HH9
> N6ZO/6Y5
>
>
>
>
>
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Rob
> Atkinson
> Sent: Sunday, December 30, 2018 9:52 AM
> To: topband@contesting.com
> Subject: Re: Topband: Inverted L improvement question - Part 2
>
> Hmmm....you DID relocate or rebuild your ground system so it converges
> on a point below the bottom of the 100 foot tall wire right? I mean,
> you aren't using the 43 foot vert. ground system with the 100' wire?
> A series fed vertical isn't rocket science so let's not over think
> this. If it doesn't work well it is probably inefficient. I'd make
> sure your ground system is adequate. No, you can't use an existing
> ground system that converges on a point 30 or 40 feet away from the
> 100' wire. Yes, I've had people ask me if they can do that, so it is
> worth mentioning.
>
> You can go the elevated route, but it is _critical_ that it be
> constructed correctly to adequately replace a full ground system at or
> below grade. You need four radials parallel to earth extending out
> 90 degrees from each other and their lengths must be equal and 90
> degrees long (1/4 w.) at frequency. The ends must be h.v. insulated.
> They should be elevated 20 feet on 160 m. to completely de-couple from
> earth.
>
> 73
> Rob
> K5UJ
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