[TenTec] Paragon II LSB/USB audio differences.

[Mark Kenward]

Thanks, Ken.

Yes, my first  job was to set the bfo's correctly, at least LSB, USB and CW 
transmit...got them within one Hertz.  I had to mal adjust the FSK bfo's in 
order to get the other 3 on freq...(neither I nor the friend uses FSK, bust 
uses AFSK, so no worries there. But if I adjusted whichever is first in the 
manual, FSK low, I think, it was impossible to set the CW transmit offset, 
it would be 985 Hz, or some such.
I chose to set LSB/USB and cw transmit since FSK was not being used.

I set the reference oscillator, and adjusted the passband tuning 
frequencies.

Also set carrier balance.

I tried adjusting the LSB BFO a bit, but as soon as you do that, you are off 
frequency according to the dial frequency.

I even tried replacing the 9mHz 2.4 filter, to no avail, same situation.

I thought of going to WWV on 10 MHz, and setting sideband frequencies the 
same, by using a soundcard scope to show and set according to the 500 and 
other WWV transmitted frequencies.  But when I did this, you couldn't switch 
from one sideband to the other and be on frequency..might be 1/2 kHz  apart, 
and although they both sounded the same, the dial readout was wrong.(and 
adjusting reference oscillator would just make it off on the other bands.

As I had posted earlier, I am within 50 Hz from 160 to 10 meters carrier 
wise, and cw transmit is right on across the bands, dead center in my cw 
filters on my omni 6 PLUS rigs, so it seems isolated to LSB BFO circuit.
(I was actually hoping there was an adjustment to center the sidebands in 
the balanced modulator loop, and freely admit I am not an expert at this, 
but I dont twirl slugs or caps just to "see" what will happen, ha ha ha)  So 
apparently, I have an aged component in LSB BFO circuit.


Again, USB sounds great, good frequency response. LSB is clean, on 
frequency, but just narrow, maybe 2.1 kHz.....I have been using it, but I 
traded it to a buddy, (with full disclosure, of course), and he is happy 
with it. But I just wanted to make it perfect for the guy. he deserves it.

My other thought was to put in a 2.8kHz filter...this  might solve the 
problem, though in a back door way.

Thanks to all for advice.

K8VF

----- Original Message ----- 
From: "Ken Brown" <ken.d.brown at hawaiiantel.net>
To: "Mark Kenward" <k8vf_mark at centurytel.net>; "Discussion of Ten-Tec 
Equipment" <tentec at contesting.com>
Sent: Sunday, April 06, 2014 12:13 AM
Subject: Re: [TenTec] Paragon II LSB/USB audio differences.


> The LSB or USB transmit signal is produced in the balanced modulator, and 
> then filtered to remove the unwanted sideband. The DSB signal that is 
> eventually run through the filter, to remove the unwanted sideband is 
> generated by combining the voice audio with the BFO. The signal produced 
> by the balanced modulator is supposed to be a clean double sideband 
> signal, with very little carrier. The carrier balance adjustment nulls the 
> carrier, and any residual carrier is further attenuated by the SSB filter. 
> What is left of that DSB signal after passing through the 2.4 kHz filter 
> is dependent on the BFO frequency and the shape of the filter. If it 
> sounds real good using one sideband, and not good using the other, they 
> are really only two possible causes either 1) the BFO frequency is wrong 
> or 2) the filter has poor symmetry. (This assumes there is not something 
> else changing, that should not change, when you change sidebands, such as 
> some control signal which should be identical for both sidebands, but 
> somehow changes. For instance, the balanced modulator gets unbalanced to 
> produce CW. It the logic that controls that is messed up, and unbalancing 
> the modulator in one SSB mode, that could be a problem. A leaky diode or 
> bad gate in the control logic might do that.) The only things that should 
> change between operation on LSB versus USB is the BFO frequency, and some 
> correction to the frequency readout, or shift of some other oscillator to 
> make the frequency display correct. There should be no change in the audio 
> level or frequency response feeding the balanced modulator, and no change 
> in the way the balanced modulator works.
>
> Most SSB filters are not perfectly symmetrical, and there will be some 
> minor difference in the sound of your transmitted signal when switching 
> sidebands. The difference should be something you really have to listen 
> carefully to notice. It should not be such a big difference that it sounds 
> "bad" on one sideband and "great" on the other.
>
> How have you confirmed the BFO frequencies are correct?
>
> DE N6KB
>
>
>
>
> On 4/5/2014 4:34 PM, Mark Kenward wrote:
>> i have set  Reference oscillator , and the BFO's on the rig.
>>
>> Rig is on frequency as discussed a week or so ago.
>>
>> My issue is this.
>>
>> USB sounds great on transmit.
>>
>> LSB, however, is thin. Narrow, like you are talking through a 1.8-2.1 kHz 
>> filter.
>>
>> I tried another 2.4 filter in 9mHz slot, with no change.
>>
>> Can someone tell me what to adjust to move the USB and LSB transmits more 
>> to the center of their respective ranges.
>>
>> I am happy with the rig so far, but it is obvious that LSB needs an 
>> adjustment, and of course, it is not the BFO.
>>
>> I have a friend who wants the rig, and I would like to make it perfect 
>> for him.
>>
>>
>> Thanks for any help.
>>
>> Mark
>> K8VF
>> _______________________________________________
>> TenTec mailing list
>> TenTec at contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>