Hi Robert....I homebrew my own connect cables...never did like the prepared
versions at all for the reasons you specified...
One thing I do have here is not an antenna switch box...I use an old drilled
out brass door hinge, bent at a right angle, that I drilled out the screw
holes to install bnc male connectors. All of my coax RG 8X cabeling (I run
barefoot) for the hf rigs go to that central "panel" then to respective
transmatches, that feed either a 40 ft vertical dipole or a 100 ft doublet
with capacity hats on the ends.
The vertical dipole is fed via a revamped Johnson Matchbox that a fellow up
in Washington State built up for me that expands the matching network.
Balance is excellent..if my xyl's computer speakers and tv in the shack is
any indication as well as matching.
The big doublet is fed (currently with either a homebrew balanced linked
coupled transmatch or an old Dentron Super tuner plus via its internal
balun). I am having another revamped Johnson Matchbox tuner manufactured for
me for that antenna.
Both antennas are fed with 450 ohm (for now) twin lead.
Have been hamming for over 25 years...facinating hobby...still on steep
learing curb!
----- Original Message -----
From: "Robert & Linda McGraw K4TAX" <RMcGraw@Blomand.Net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Cc: <listacct@longwire.com>
Sent: Monday, November 28, 2005 5:53 PM
Subject: Re: [TenTec] Comments on "Repairs"
> Larry:
>
> One concern that surfaced from the description of your station and
> grounding
> technique. You indicated that you have a common ground connected to an
> outside driven ground. Is this ground rod connected or bonded to the AC
> mains ground? It should be in order to prevent a difference in voltage
> between the station ground and the AC mains ground. Typically your radio
> is
> connected between these two and thus any current differences are flowing
> through the radio equipment. Not good.
>
> With balanced lines into the shack, if they are indeed balanced, then
> there
> should be NO circulating currents. I would certainly question this aspect
> of the station. Why would you have circulating currents or RF in the
> shack
> if the line is balanced? It is normal for a small amount of imbalance to
> be
> in existence due to different ground conductivity under the legs of the
> antenna. I find it acceptable to have current differences in each side of
> a
> balanced line to be less than 10% worst case. More like 2% to 3% in my
> case
> in practice.
>
> With the tuner and its internal SWR metering system you get good results.
> OK, I'll buy that. However, what is the SWR the radio is seeing? This
> must
> be measured at or in the radio. Now to that end, with the ground system
> you
> describe I could easily suspect that one of the diodes D2 or D3 on the Low
> Pass Filter board could be defective thus caused by a nearby lightning
> strike and a step voltage between two different grounds. With either
> diode
> at fault the radio ALC and power control system may be failing to protect
> or
> control the radio. I've seen this before. Others relate the same story.
>
> Now I know this doesn't explain why the Yaesu works fine and the Tentec
> doesn't. Could it be that the Tentec stays connected in the system all
> the
> time or most of the time and the Yaesu sits detached from the system most
> of
> the time? A recent nearby lightning tap may have taken out D2 and or D3.
>
> Regarding commercially made RG-213 jumpers. OK good I'll buy that but
> I've
> seen new, commercially made jumpers in two way and broadcast equipment
> found
> to be defective out of the box. Spin the shell off of the PL-259's and
> check to make sure the braid is soldered and the center pin is soldered.
> A
> good check with an ohm meter is wise. Better yet, a dummy load on one end
> of the cable with the MFJ bridge on the other end and do a wiggle and
> jiggle
> check. Any change in SWR is a bad cable or connector installation. In my
> book, new and commercial does not automatically imply good. I'm like a
> cat......always suspicious. At one place I worked, a failure rate of 3%
> AQL {acceptable quality level} or less was considered passing grade.
> That
> says 30 out of 1000 cables could be bad and the company is happy with
> their
> quality.
>
> You have made some very good choices on several points. Your choice of
> Polyphaser and Wireman lightning protection equipment is as good as it
> gets
> in my experience. Frankly, I don't care for the RM-35M power supply
> unless
> you have a 20A fast acting magnetic breaker between it and the radio. It
> has the ability to instantly dump 35 amps of current into the PA which is
> only rated for about 26 amps max. OK so it works with the Yaesu but they
> use a totally different over current protection scheme. Tentec does not
> monitor or control emitter currents on the PA or driver stage. They use
> the
> SWR and ALC circuit to control drive power. This area could be the source
> of your evils.
>
> More good dialogue please. We'll solve the problem to component level if
> you wish.
>
> 73
> Bob, K4TAX
>
>
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