[TowerTalk] 2 questions

[Joe Subich, W4TV]

 > Using double pole relays in binary trees is normally considered a very
 > unreliable way to go in industry.

The RCS-10 does not use double pole relays - at least according to
the schematic in the Instruction Manual.  It uses seven SPDT relays
connected with four, two and one coils connected to the A. B and C 
control lines respectively.

> I have used the more conventional RCS4 and 8 that use the second set
> of contacts on each relay to prevent any other relays being active
> other than the one selected.

Again, according to published schematics there are no "interlock"
contacts in either the RCS4 or RCS8 relay units.  The RCS4 uses three
relays in a binary (one feeding two) arrangement while the RCS8 uses
five "form X" relays in a "star" configuration.  The RCS-8 is designed
specifically to allow multiple antennas to be connected simultaneously
(paragraph 1, page 3 of the Instruction Manual).

73,

    ... Joe, W4TV



On 7/8/2012 12:50 AM, K8RI wrote:
> On 7/7/2012 11:00 PM, Joe Subich, W4TV wrote:
>>
>>    > First question. I have an Ameritron RCS-10 that doesn't seem to work
>>    > on all positions. Mine only works on 1-4 with no connection on the
>>    > other positions. What would cause that? It almost seems like 2 and 6
>>    > are hooked together and 1 and 5 too!
>>
>> RCS-10 uses a "binary tree" arrangement of relays.  You will probably
>> find the input relay has been arced so that both the normally open and
>> the normally closed contacts are connected at the same time (all the
>> time).
>
>
> Using double pole relays in binary trees is normally considered a very
> unreliable way to go in industry.  Solid state logic is much more
> reliable and only takes 4 lines to count to 10 (BCD) and is simple to
> decode with one chip.  I can't imagine why anyone would use relays in a
> binary tree.  I've never seen an RS10 so I can't verify the
> construction, but I have used the more conventional RCS4 and 8 that use
> the second set of contacts on each relay to prevent any other relays
> being active other than the one selected.
>
> 73
>
> Roger (K8RI)
>
>>
>>    > Second question is about the need/benefit of grounding coax cables at
>>    > the bottom of a tower.
>>
>> It's called lightning protection.  You want the shield of all cables
>> connected at both the top and bottom of the towers so that a lightning
>> strike can't cause a high voltage between the tower and cable shield
>> which would "puncture" the insulation and put the high voltage on the
>> chassis of any connected equipment.  There is a lot more in the literature.
>>
>> 73,
>>
>>       ... Joe, W4TV
>
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