[ARC5] First Post and Questions

[AKLDGUY .]

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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