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[TowerTalk] Alpha-Delta 1X4 Antenna Switch Problems

To: "Tower and HF antenna construction topics." <>, "BEARS - Exec Board" <>
Subject: [TowerTalk] Alpha-Delta 1X4 Antenna Switch Problems
From: <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Tue, 30 Mar 2010 14:18:37 -0500
List-post: <">>

I am delighted to see the comments posted here on the Alpha Delta 4 position 
HF (UHF connector style) coaxial switches.  At our Emergency Operations 
Center Communications Station (W0MA), we have no fewer than 16 switches 
installed on two patch panels (each panel is made of 1/4 inch thick 
aluminum) of 8 switches each. One panel supports the HF antennas/rigs while 
the other panel supports the VHF/UHF antennas and rigs and includes at least 
2 or more of the 4 position switches with Type - N connectors.  The HF patch 
panel has been in operation for the past 10 years, seeing full legal limit 
amps running through it. If my memory serves me correctly, I think that I 
have replaced 1 or 2 switches at the most. This is in an environment that 
see fairly consistent weekend operations and testing.  The VHF/UHF patch 
panel is much newer, sees power through it at less than 100 watts and has 
experienced no problems. We have also seen one "out of the box" failure of a 
new switch which was returned to AES for replacement rather than sending it 
back to Alpha Delta. I would also note that failure to mount the original 
version of the Alpha-Delta switches on a completely flat surface could cause 
mis-alignment of the internal components of the switch due to the switch 
design and locating system for the switch shaft.  I believe that this was 
corrected in the "Rev B" design switch introduced a couple of years ago.

That said, I currently have 3 of the HF type Alpha Delta 4 position switches 
installed in my own shack and have not had as good a performance record as 
what we have seen at our EOC station. Having procured these switches in some 
quantity during the past 10 years, there have clearly been some 
configuration/design changes to the switches, at least one of which was 
officially recognized and marketed by Alpha Delta and "new and improved rev 
B".  Alpha Delta also now specifies that the switch should not be exposed to 
an in line SWR of great than 2:1.  I suspect that the "metal tabs" which 
comprise the switch elements will deform (bend /warp. etc) when exposed to 
the heating seen at high power levels with SWR's great than 2:1.

Unfortunately, my station design, based upon using 1 solid state (modern 
station) and 3 boat anchor stations, with not much more than the power 
output of a pair of 3-500Z's on SSB/CW and power output on the boatanchor AM 
station limited to 50 watts, I use a multi-band dipole for 80 thru 30 mtrs, 
(mostly on 80 & 40) fed by 450 ohm ladder line, coupled to a 1:1 
DX-Engineering balun at the window to the shack, then 9913 Flex coax into 
the shack, antenna switches and to the rigs. I have an antenna tuner located 
at each station so that it is easy to adjust the antenna from each of the 
operating positions.  Thus, both the coax switches and approximately 15 feet 
of 9913 Flex coax see some very high SWR's on the lower HF bands. This 
problem is not relevant on 10-20 mtrs where my antenna is a resonant 
tri-bander. With that said, I seen at least 2 of my Alpha Delta switches go 
"out of alignment" causing intermittent  or total loss of contact through 1 
or more of the switch positions. Opening up the switches and adding a small 
solder "contact point" to each of the tabs so as to build up the contact 
area thickness has the effect of making the switch arm movement  not as 
critical as it had been,  and seems to help solve the problem and I am able 
to get the switches to continue to function.

However, at the end of the day, I believe that the old Waters or B & W 5 and 
6 position coax switches built from standard HV/High current ceramic rotary 
switches are more reliable and I am about to convert back to the old 
switches in the not too distant future.

I would really like to learn what others have experienced with the Alpha 
Delta switches.

Look forward to hearing from all,

Dave, K2DP
Trustee, W0MA - St. Louis, MO

----- Original Message ----- 
From: "Felipe Ceglia" <>
To: "Tower and HF antenna construction topics." <>
Sent: Monday, March 29, 2010 6:42 PM
Subject: Re: [TowerTalk] Alpha-Delta 1X4 Switch Problems

>I had problems on 2 out of 4 switches. Actually, I must say that I sold the
> fourth before opening package, which makes 2 out of 3.
> Wont buy it again... Need to find something similar.
> 73,
> Felipe - PY1NB
> 2010/3/29 mike stokes <>
>> I have 4 of them and never have had any problems.  I hope it stays that
>> way.
>> Mike
>> KK9V
>> On Mon, Mar 29, 2010 at 4:21 PM, Jim Brown <
>> >wrote:
>> > Crew,
>> >
>> > I own five of these switches purchased over a period of sevral years 
>> > from
>> > various dealers, and have had at least two failures. In one, the #4
>> > position simply didn't work. I opened it up to find that it could not
>> > possibly work -- the wafer that was supposed to mate with the rotating
>> part
>> > was too short! I discovered a problem this weekend in a second switch
>> this
>> > weekend -- the #1 position doesn't make contact. When it was newer, I
>> could
>> > fiddle with it and get it to mate. Now even that doesn't work. I opened
>> it
>> > up and found no obvious problem, except that the two contacts didn't 
>> > meet
>> > parallel to each other. Other positions in both switches work fine.
>> >
>> > These switches come with labels over the rear chassis screws warning 
>> > you
>> > not to remove them, lest parts fly out and self destruct. And, of 
>> > course,
>> > doing so voids the warranty. But, I ask, what good is a warranty on a
>> > product that costs a third of what you paid for it to ship back for
>> repair,
>> > and is void if you bother to carefully open it up to check for obvious
>> > problems? After all, we are hams, not CBers. With both of the switches
>> that
>> > have problems, the labels were intact, indicating that they had not 
>> > been
>> > opened.
>> >
>> > Two failures out of five is pretty bad, especially for such a simple
>> > product, and inexcusable when one of those failures HAD to have been
>> found
>> > in final test (if there WAS final test). When a group of us were using
>> > switches like these on a California QSO Party county DXpedition to 
>> > switch
>> > antennas and filters, our host, N6RNO indicated that at least one of 
>> > his
>> > switches had a problem that he hadn't figured out yet. Is this isolated
>> to
>> > us?  Anyone else seen these problems?
>> >
>> > 73,
>> >
>> > Jim K9YC
>> >
>> >
>> > _______________________________________________
>> >
>> >
>> >
>> > _______________________________________________
>> > TowerTalk mailing list
>> >
>> >
>> >
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