I measured it using the parameters you show on your web page
http://www.ronc.users.sonic.net/Frequency%20Response%20jpg.jpg which is
entitled 'Orion II Frequency Response', and using the technique you
described in your email with one variation: I used a power level of 30w
but still with no ALC action. I did a separate test with ALC acting at
all tone frequencies which of course showed a flatter response - down to
75Hz before it began to roll off.
It occurs to me that there is another variable but which is unlikely to
have an effect: my O2 is a CE approved model. I didn't think the EC
concerned itself with the frequency response of transceivers but - since
they tend to meddle with practically everything else - I could well be
wrong :-)
Pete, G4PLZ
Ron Castro wrote:
Was that measured on mic or Aux input and at what reference frequency
and power output? Also, I assume the TX EQ was set to flat.
There is a very good reason why the measurements are not the same as the
published specifications. They were made on an Orion I using version 1
software which had an entirely different sideband generation methodology.
Ron Castro
Chief Technical Officer
Results Radio, LLC
----- Original Message ----- From: "Peter Connors" <monotreme@ntlworld.com>
To: "Ron Castro" <ronc@sonic.net>; <tentec@contesting.com>
Sent: Wednesday, July 19, 2006 11:39 AM
Subject: Re: [TenTec] Is Orion really worth it? Given the published
problems?
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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