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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