My apologies to all for the extreme delay in responding. I got a long
wood splinter under my pointer finger nail and it got infected and
ballooned rapidly necessitating a visit to my internist and then to a
hand surgeon who had to cut open the nail and remove some skin and the
splinter. Unfortunately he had to cut it open again 10 days later. As
you can imagine it was a mess, extremely painful and almost impossible
to type with the multiple layers of bandages. 5 trips to the hand
surgeon and 3 weeks later it is finally mostly healed.
Many thanks to NO9E, NA6O, W5JMW, W4EF and N3AC for their thoughtful and
very helpful responses.
I had checked the coax, control cables, dummy load, Wire elements and
feedlines just to be thorough and everything looked fine. And then I
opened the ACB-80 relay box and spotted a fully charred relay and partly
blackened circuit board and then noticed that the other two relays next
to it either had significant corrosion or lichen growth inside, or both.
Whatever was on the relays likely caused the relay immolation but it
was surprising to see given that the relay unit was held in place with
antenna ports facing down and then that was placed under a large heavy
duty plastic bin to prevent water, leaves, etc. from getting inside.
I am sending the relay unit back to DX Engineering for service along
with the control box. My understanding is that there is currently a 6 -
8 week backlog for repairs. The unit is 27 years old. It would be
great to be able to get another 10 - 15 years out of it. I won't need
it after that.
73 and thanks for all of your help and information!
Bob, KQ2M
On 2022-06-27 14:17, Ignacy Misztal wrote:
If a mismatch in the 4 SQ should cause high dumped power but little
SWR change, it suggests that the Comtek box has a problem.
Perhaps during testing with the elements out of order something has
fried.
Comtek has a reputation of less reliable relays. My 2 year old Comtek
stack match stopped switching and a KW sent to the stack fixed the
issue.
Ignacy NO9E
On Sun, Jun 26, 2022, 19:23 <kq2m@kq2m.com> wrote:
Hi,
Before WPXCW one month ago, my wire 80M 4-square using the COMTEK
ACB-80
was working very well, with ~ 1500 W out and 100 w reflected at 3.5
mhz
and ~ 1500 W out and 50 w reflected at 3.7 mhz. The F/S and F/B wer
excellent and about as predicted when the DX station signals were
low
angle.
Between then and now (one month) we had two violent windstorms and a
few
nasty T-storms, with gusts approaching 50 - 60 mph but tame compared
to
what it has been through in the past. 2 wire elements broke off,
the
F/B and F/S disappeared and the forward power dropped to ~ 800 w
with
350 w reflected from from 3.5 - 3.7 mhz. That's normal and to be
expected.
However, when I fixed the two elements today, while the F/B and F/S
improved somewhat, the forward/reflected power did not go back to
the
usual values. That is NOT normal.
I checked each of the connectors and continuity at the bottom of
each
element and everything appeared to be fine. I checked all the
phasing
lines and they appeared normal. All the elevated radials were in
the
air at their normal elevations. I could not find anything wrong.
There
was one sketchy looking connection on the feedline to the shack and
I
made a new connection with a new Amphenol pL259, but there was -
still ~
800 w forward 350 w reflected from 3.5 to 3.7 mhz.
I seem to remember something like this happening about 10 years ago
with
high reflected power and loss of F/B and F/S as a result of multiple
COMTEK external relay box cold solder joints that were not obvious.
DX
Engineering checked it out found the cold solder joints (that COMTEK
did
NOT find) and fixed them and priority shipped it back to me so that
I
would get it before CQWWCW which I did! But the F/B and F/S was
worse
then than it is now so I am not sure that it is the same thing.
What is striking to me is that the forward power has uniformly
dropped
and the reflected power has uniformly risen across the entire band
as
though the entire array was detuned by 500 khz, suggesting something
systemic. I suspect that the problem is in the relay box but I
can't
figure out what may be causing this.
Has anyone experienced a similar problem with their ACB-40, ACB-80
or
ACB-160? Does anyone have any idea of what to do look for next?
Tnx & 73
Bob, KQ2M
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|