[ARC5] 10 meter BC-454 a bit more

[Geoff]

Every now and then to keep electrolytic caps happy and spiders cooked I'll 
light off the DX-60, Adventurer with Johnson screen modulator and a couple 
of similar WRL's. Then into the DTR-1000L which runs a loafing 8877 for some 
serious PEP signal. Watching the scope when tuning, the reports are always 
very favorable and it is far easier to get decent fidelity than with 
underwhelming mod iron that usually saturate long before 100% modulation.

Carl



----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Geoff" <geoffrey at jeremy.mv.com>
Cc: <Arc5 at mailman.qth.net>
Sent: Thursday, March 07, 2013 12:52 PM
Subject: Re: [ARC5] 10 meter BC-454 a bit more


> On 7 Mar 2013 at 9:29, Geoff wrote:
>
>> Now all you need is a 6CW4, 6GM6 or 6EH7 (or SS) preamp to find
>> another layer of signals and crank the 12SG7 gain back a bit.
>
> Sure. I should continue to make a silk-purse out of this hog's ear. ;-)
>
>> Im not at all surprised at the 454 performance since it is missing all
>> the loss associated with a bandswitching receiver.
>
> Well, not having (yet) had your experiences with receivers, I must insist 
> that I
> am quite surprised at the results of this job. I had about half expected 
> its
> performance to be about on par with my S-41G at 10 meters: i.e. dismal.
>
> It most certainly is not.
>
>> All you need now is a simple AM/CW TX to enjoy the coming 10M E season
>> DX. Time to hack an ARC5 TX maybe?
>
> Well, I still have a DX-35. I'd bet that would work well. However, I also 
> have
> several badly modified ARC-5 transmitters here. All are unrestorable, 
> IMHO.
> All have significant holes in various places, and many missing parts, and
> added parts. I suppose I could use one of those.
>
>> A carrier control audio stage can
>> be built right in.
>
> SInce the time of my first DX-35, I have always had a great liking for
> controlled-carrier AM modulation. There was an article in ER magazine some
> time ago which went into great detail on that method.
>
> I also like so-called "cathode" modulation. There were several articles in 
> QST
> magazine and in the Handbooks on it. One was entitled, "The Simplest
> Modulator". It simply plugged into the key jack of any cathode-keyed
> transmitter. It is actually a combination of cathode and grid modulation.
>
> I tried it once and it works very well indeed for being so simple.
>
> One advantage to controlled-carrier AM is that it drives a linear amp much
> more "kindly" than straight plate modulated AM.
>
> Another is that if used properly, it can sound like SSB (actually DSB) to
> someone on SSB.
>
> Ken W7EKB
>
>
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