[ARC5] First Post and Questions

Mon Jul 3 18:43:34 EDT 2017

Hello Bobby,
The list is always pleased to get a new member!

I suggest you tell us the documents you have (or know about).
In particular I have a copy of the manual for the "Army" (BC-45x
versions).   A helpful list member sent me a copy.  If you don't have
this, you'll find it useful (and it is quite different from the ARC-5
document).
Neil gave you some valuable info in his recent posting (that is - that
keying is done in the modulator unit) and you have already heard that.
Dave Stinson wrote an article called "Getting your ARC-5/command set on
the air without hacking it" (or something like that).   That has been
mentioned here too.   Also, Neil wrote (in Wikipedia) that there are 3
different versions of these sets - (or four if you count the "K" series)
and there are significant (but small) differences between the versions.
Knowledge about this info is a good starting point.  For example the ARC-
5 rack connector (for the transmitters) is different from the ATA (or
SCR) versions.
When I first came across the "command" sets I had only the set I held in
my hands.  I had no idea about the three different "versions" or that
circuit diagrams (and even complete manuals) were available.  I designed
my own power supply without this knowledge - and I would have produced a
different design had I known this!  I had no knowledge of this group
(and it probably didn't exist, because this was some time ago).
Finally, there is considerable dispute about modifying these sets.  I
take the view that every set is valuable in one way or another, and I
try to keep the set in what I call "the spirit" of original design.
"The spirit" means (in my mind) careful consideration of design (or
restoration), professional work (if changes are made), good quality
components.  I'm naughty!  I use heat-shrink sleeving when I wire sets.
I use (horrible, horrible) plastic cable ties (but I don't have any
truly original sets.)   On the other hand I soon expect to start working
on a BC-457-A that David Stinson called "desirable".  Black paint-work,
silver name-plate on top.   I'll treat this set with more respect!!  On
the other hand I DO want to put it on the air, because I take the view
that so few people would even recognize that this is a "desirable" set
that the only way it will survive is by actually being on the air.  Even
well informed members of my local radio club would say, "Oh, that's just
an old WWII transmitter.  Oscillator plus a pair of PA tubes.  It's not
worth anything."  There is very little real understanding of these sets
(and their role in history).
Welcome to the group!

   73 de Les Smith
   vk2bcu at operamail.com

On Tue, Jul 4, 2017, at 07:31, AKLDGUY . wrote:
> Hi Bobby
> 
> Congratulations and welcome on joining the list. You stated that
> you "plan on using conventional keying (keying relay built in the
> BC-457 A)".> 
> There is NO keying relay in the BC-457 A or in any of the ARC-5
> transmitters. The relay connected to the antenna post (if still
> fitted) and the relay mounted on the sidewall next to one of the 1625
> sockets are SELECTOR relays. They become operated when the pilot
> selects that transmitter. They stay permanently operated even while
> receiving. The bottom relay prepares a path for the VFO B+ and the
> cathodes of the 1625's. The keying and Push To Talk is performed by a
> relay in the modulator which switches the +550 volts from the
> dynamotor to ALL transmitters in the rack. Only the one with the
> selector relays operated will function.> 
> This is a very common misunderstanding. The bottom selector relay is
> actually fast enough to follow keying and many hams have successfully
> keyed the transmitters by using it, but the RC constants in the 1625
> screens and VFO B+ do not then come into play and the result lacks
> proper shaping of the keyed waveform.> 
> 73 de Neil ZL1ANM
> 
> 
> On Tue, Jul 4, 2017 at 6:58 AM, Bobby Drummond
> <alphak4ja at gmail.com> wrote:>> Hello to all.  Name here is Bobby Drummond and the call is AK4JA.
>> I've been licensed as a Amateur Radio operator for 35 years and just
>> heard about and signed up for this list.>> 
>> My passion is homebrewing (radios that is) and CW.  I'm not averse to
>> restoring old gear as well and hence we arrive at the real reason I
>> am now a member of this mailing list:  I bought a BC-457 A
>> transmitter at the Dayton Hamvention this year.>> 
>> Have you seen the recent commercial where two women are talking
>> about a sofa just acquired and the owner says, "I had to have it!"
>> (then two burglars are looking at the same sofa later while
>> burglarizing the same house and one of the two says the same thing:
>> "I had to have it."  Guess what I thought when I saw the BC-457 A on
>> a table in the Hamvention Flea Market area in Xenia?   Yep, the
>> exact same thing.>> 
>> The plan:   restore the BC-457 A using every trick in the book to
>> make it work reliably and be as stable as possible.  The reason being
>> that I want to put it on 60 meters (CW, of course - see first
>> sentence in second paragraph above)   The BC-457 A "tops out" from
>> the factory at 5.3 MHz according to what I have read and I want to
>> put in on frequencies from 5.332 to 5.405 MHz.  I'm thinking that
>> some minor adjustments to the oscillator tuning should do the trick.
>> Adjustments that would be easy to "undo" if I want to put the radio
>> back in "just like it left the factory" condition. I would also like
>> to put it on the air regularly in a net if that is possible, too.>> 
>> Any suggestions, hints, caveats, or advice related to doing said
>> tasks would be greatly appreciated.>> 
>> Here are some questions that come to mind:
>> 
>>    1) Has anyone on the list already done what I am thinking about?
>>       (I'm especially referring to putting a "Command Set" on 60
>>       meters)>> 
>>    2) Is there a net for ARC5 or equivalent radios that I can listen
>>       to now?  If so, how can I get details about the net?>> 
>>    3) what is the best cleaner to remove oxidation from the roller
>>       inductor?>> 
>> 
>> My plans are to power the BC-457 A with a power supply that I will
>> build, using the best voltage regulators available and with a large
>> enough transformer to be rated at least double the power requirements
>> of the BC-457 A. I will power the filaments with a tightly regulated
>> 24 Volt DC supply and plan on using conventional keying (keying relay
>> built in the BC-457 A)>> 
>> So, that's it for my first post.  Any help would be greatly
>> appreciated.  With the long and storied history of these rigs, built
>> and operated by our Greatest Generation, I think it would be an honor
>> and privilege  to restore one and put it to good use on the 60 meter
>> ham band, a band that I really like a lot.>> 
>> 
>> 73 de AK4JA
>> 
>> 
>> 
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