[ARC5] Backwave

[Dennis Monticelli]

There seems to be a lot of interest so let me clarify my statement
regarding the observed inaudibility of the backwave,.

My friend has discerning ears and is located within my ground wave (approx
3 mi).  Our signals are strong at each other's QTH's.  So the measurement
is only good for the dB spread from S9+ to local noise level.  In
performing the test I wanted to know not only if the backwave was audible
statically, I wanted to know if the extreme chirp at key down was audible
because that 2KHz jump is occurring as the PA is turning on.  Nothing was
heard during the test.  The freq jump probably escaped the ear because the
chirp was happening so fast.  The only reason why we hear classical chirp
is because the time constant of the sagging PS caps falls neatly within the
dit period.

40M is the extreme test for ARC-5.  The backwave will be less at 80M
because the interelectrode capacitances of the tube are fixed regardless of
freq band.  Recall that the rig has a fixed neutralization capacitor
(unless somebody removed it) and that helps in reducing the net backwave
energy that enters the tank because some degree of cancellation occurs.

Dennis AE6C

On Mon, Oct 26, 2015 at 7:57 AM, Bill Cromwell <wrcromwell at gmail.com> wrote:

> Hi,
>
> Unacceptable or not really is subjective..just as you have said. For me it
> is unacceptable. I have tried dynamotors, too and the noise grates after a
> short while. We all know there are hams (and other users) who not only
> don't object to the noise but like it. There is something for everyone.
> Personally I think they are way cool but the noise is offputting. Some
> people are annoyed by CW. Try to imagine that <evil grin>.
>
> 73,
>
> Bill  KU8H
>
>
>
> On 10/26/2015 10:03 AM, arc5 at ix.netcom.com wrote:
>
>>
>> I confess I don't understand this talk of mechanical relay noise in these
>> transmitters. I found the selector relays when used for keying to be fairly
>> quiet, especially when compared to something like the 375 or TCS. If one
>> has not disconnected the antenna relay, then surely that is quite noisy and
>> unacceptable. But the selector relay makes very little noise in my
>> experience. Of course, how much is acceptable is purely subjective. One
>> man's noise is another man's music.
>>
>>
>> Sent from my ain't-so-smartphone.
>>
>>
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