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[TowerTalk] Budget 4-Pack

To: <>
Subject: [TowerTalk] Budget 4-Pack
From: "Jim Thomson" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Tue, 2 Mar 2010 19:16:21 -0800
List-post: <">>
Date: Tue, 2 Mar 2010 12:08:54 -0600
From: Stan Stockton <>
Subject: Re: [TowerTalk] Budget 4-Pack?


Two DPDT relays for each antenna - one for each rig.  Activating a  
relay by Rig A with one set of contacts disables the other rig from  
being able to activate the same relay for the same antenna and vica  
versa.  If you are also wanting to prevent the other rig from  
transmitting at all that is another box to build.  Let me know if this  
is enough info.  If not I'll draw it.

Stan, K5GO

### That's not how my six-pack works.  The 6 x pack uses 3PDT
relays.  12 x relays in all, 6 x for radio..'A'.... and 6 x'B' 

##  for a 4-pack, and 2 x radio's... a total of 8 x 3PDT  relays required.
The 1st pole of each relay simply OPENS OFF the  coil of it's mating
relay.  [ and vice versa].    IE: radio 'A'   can grab any 1 of the 4 x ants'.
Radio 'B'   can grab any of the 3 remaining available ants.  IF radio
'B'  is set to the same ant as radio 'A'....[say ant 1] , then radio 'B'
 relay #1'  will not operate ! 

##  It's a real simple mech interlock arrangement really. It also provides
aprx 70-80db  isolation between radio A + B 's  main 2 x coax inputs,
and 60 db between either radio and any ant port [ this one is real important]. 


then click on.. 'users guide'      Then scroll way  down the user's  guide,
and u will see the complete schematic !    Notice that the 1st pole of
each relay only uses 2 x contacts  [the common and normally closed]. 
The normally open contact is not used.. or depicted on schematic[pole1].

These NC  contacts are wired to each other's coils.[interlock]. Coil-NC-NC-Coil
The remaining 2 x pole's of each relay are used to do the switching,, and
provide HIGH isolation [when de-energized]  The 2 remaining poles have 
their  RF contacts wired in SERIES !  

##  The high isolation comes about by  using the 2 x sets of 
contacts in series.  When  de-energized, the leakage path is
Doubled. You have the stray C of each open contact, now in 
series with each other = 1/2 the stray C = higher isolation  compared
to, if just one set of contacts used.    Hence the use of 3PDT  relay's
and NOT  DPDT relays.   The 3PDT  relays used in the 6 x pack use
gold plated contacts.  It will handle 5 kw cxr, no problem. 

##  The  relays are mounted [soldered] onto PC board, and use strip line
technology to ensure the swr is dead flat  from 160-6m. [ no comp caps
used either]  

##  One caveat with the 6 x pack.... being a 2 x 6 matrix switch means ALL
6 x ant ports, when NOT in use, have floating center conductor's !     

##  IE:  radio 'A'  is on ant #3..... and  radio 'B'  is on ant #5....  ant 
1-2-4-6  have open/floating center conductor's. 

##  when done for the night, and everything shut off, ALL  6 x ant ports
are opened off.  

## On my 15 kw rat pack, [ 1 x 6 remote switch]  ALL  un-used ants
have their center conductor's GRNDED !   IE: all de-energized relays.

later... Jim  VE7RF.... owner of 6 pack    SN  001   

On Mar 1, 2010, at 1:40 PM, "Barry Fox" <> wrote:

> I have two HF radios and 4 different HF antennas.  I would like to use
> each rig on any antenna, while obviously locking out that antenna for
> the other rig.  The commercial products 6-Pack, 8-Pack, etc are way
> over my budget.  Anyone have a schematic for a "4-Pack" or similar
> device they would like to share?  Obviously relays are the way to
> go, and I can get the RF relay switching part of it on paper but
> not the lockout logic.  Some sort of electro-mechanical exclusive-OR
> gate array / diode matrix?  Anyone been there and done that?
> TNX / 73,
> Barry - W1HFN

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