Yes adjust, switch switch, adjust, switch switch, etc etc was one of the
things that was drummed into me during my BBC training in the analogue
age. You spent the first part of each morning 'lining up' equipment
before you could actually start using it. Thank goodness for the digital
revolution (except the bits that give me rfi) for sparing much of the
endless engineering pedantry needed to guarantee a broadcast chain.
Anyway, back to the point: using your protocol my O2 s/n 05C10726
running v2.034 shows a gentle roll off: -2.6dB at 250Hz and -5.5dB by
50Hz. As far as I can see there has been no published firmware change
that would account for this difference with your sample; perhaps there
is an undocumented hardware mod or some other reason for the variation
between samples - and it is entirely possible that the O2 spec was
arrived at using a completely different test protocol.
Either way, my O2 appears to have a very good response for speech
communication so I don't think I will lose any sleep over it :-)
Pete, G4PLZ
Ron Castro wrote:
The Aux input will probably be a bit flatter, but a review of the design
shows very little in the mic pre-amp that would cause any significant
deterioration of the response. The AGC is a bit more problematic, since
there is no way to know if it is changing the input level. As we both
know from our broadcast experience, all good broadcast audio processors
intended to be used between the board and the transmitter have a "Proof"
switch of some sort that disables processing while still allowing
frequency response, distortion and noise to be tested.
Good luck and please let us know your test results!
Ron N6AHA
----- Original Message ----- From: "Peter Connors" <monotreme@ntlworld.com>
To: "Ron Castro" <ronc@sonic.net>
Sent: Wednesday, July 19, 2006 2:05 AM
Subject: Re: [TenTec] Is Orion really worth it? Given the published
problems?
Yes, the ALC would distort the response - which is why I was
interested in your protocol. I will do a run on the MIC input too but
the AUX input *should* have the flattest response.
Pete, G4PLZ
Ron Castro wrote:
You can't do a frequency response test on an SSB rig if the ALC or
audio AGC (there is one in the Orion I and II mic preamp) is acting
on the signal. I injected a signal generator into the Aux input and
ran the output at a steady 25 Watts (PWR set at 100%), and adjusted
the generator up and down across the spectrum to get 25 Watts.
Ron N6AHA
----- Original Message ----- From: "Peter Connors"
<monotreme@ntlworld.com>
To: "Ron Castro" <ronc@sonic.net>; <tentec@contesting.com>
Sent: Tuesday, July 18, 2006 10:06 AM
Subject: Re: [TenTec] Is Orion really worth it? Given the published
problems?
Yes, I see that from the measurement you report on your website but
that isn't what your bullet point was and I still don't quite
understand the need for an increase in response at 50Hz. I think you
might mean "I would prefer the lf response to begin rolling off later".
For the measurement you didn't specify where the output is measured
from - is it at the antenna socket at full output but before ALC
action starts? This would help this ex-BBC engineer to attempt to
replicate your findings.
Pete, G4PLZ
Ron Castro wrote:
The roll-off starts at 400 Hz.
Ron Castro
Chief Technical Officer
Results Radio, LLC
----- Original Message ----- From: "Peter Connors"
<monotreme@ntlworld.com>
To: "Ron Castro" <ronc@sonic.net>; "Discussion of Ten-Tec
Equipment" <tentec@contesting.com>
Sent: Tuesday, July 18, 2006 5:00 AM
Subject: Re: [TenTec] Is Orion really worth it? Given the published
problems?
Ron Castro wrote:
3). The missing 9 dB of low frequency response at 50 Hz as shown
in the specifications;
Ron
I am fascinated to find out why a better response is needed at
50Hz. A bass singing voice might go down to 65Hz but I am unaware
of the communications advantage.
Pete, G4PLZ
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