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Re: [TenTec] Corsair II tuning

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Corsair II tuning
From: MadScientist <dukeshifi@comcast.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 26 Aug 2018 20:28:02 -0500
List-post: <mailto:tentec@contesting.com>
The Corsair II automatically selects the most popular sideband for a given 
band. Thus, one automatically gets USB on the higher bands and LSB on the lower 
bands when you are set to the “SB-N” position.

Gary

> On Aug 26, 2018, at 8:21 PM, Bob McGraw K4TAX <rmcgraw@blomand.net> wrote:
> 
> The Corsair manual seems to indicate differently.  
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Aug 26, 2018, at 8:10 PM, Greg S via TenTec <tentec@contesting.com> wrote:
>> 
>> ....Is this the model whereby one must have the switch in reverse in order 
>> to operate in USB as well?...my memory fades.
>> Greg KC8HXO 
>> 
>> Sent from my Linux device
>> 
>>> On Aug 26, 2018, at 18:47, MadScientist <dukeshifi@comcast.net> wrote:
>>> 
>>> 
>>> 
>>> 
>>> On 160 meters, the PTO (5.0 to 5.5 MHz) adds to the 5.8 MHz crystal to 
>>> produce 10.8 to 11.3 MHz. The  the 9.0 MHz IF is subtracted from this 
>>> signal to receive the incoming signal (2.3 to 1.8) MHz. On this band, as 
>>> the PTO frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 80 meters, the PTO (5.0 to 5.5 MHz) adds to the 7.5 MHz crystal to 
>>> produce 13.0 to 12.5 MHz. The  the 9.0 MHz IF is subtracted from this 
>>> signal to receive the incoming signal (4.0 to 3.5 MHz). On this band, as 
>>> the PTO frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 40 meters, the PTO (5.0 to 5.5 MHz) adds to the 11.0 MHz crystal to 
>>> produce  16.0 to 16.5 MHz. The  the 9.0 MHz IF is subtracted from this 
>>> signal to receive the incoming signal (7.5 to 7.0 MHz). On this band, as 
>>> the PTO frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 30 meters, the PTO (5.0 to 5.5 MHz) adds to the 13.99 MHz crystal to 
>>> produce 18.99 to 18.49 MHz. The  the 9.0 MHz IF is subtracted from this 
>>> signal to receive the incoming signal (9.99 to 9.49 MHz). On this band, as 
>>> the PTO frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 20 meters, the PTO (5.0 to 5.5 MHz) subtracts from the signal to convert 
>>> the 14.0 to 14.5 MHz to the 9 MHz IF.  No band crystal is used.  On this 
>>> band, as the PTO frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 18 meters (incorrect marking for 17 meter band), the PTO (5.0 to 5.5 
>>> MHz) could go either way because the crystal frequency is incorrectly 
>>> marked in schematic. I don’t know its frequency so cannot calculate its 
>>> tuning direction on this band.
>>> 
>>> On 15 meters, the PTO (5.0 to 5.5 MHz) adds to the 6.99 MHz crystal to 
>>> produce  11.0 to 11.5 MHz. The  the 9.0 MHz IF is added to this signal to 
>>> receive the incoming signal (20.99 to 21.49 MHz). On this band, as the PTO 
>>> frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 12 meters, the PTO (5.0 to 5.5 MHz) adds to the 10.5 MHz crystal to 
>>> produce 15.5 to 16.5 MHz. The  the 9.0 MHz IF is added to this signal to 
>>> receive the incoming signal (24.5 to 25.0 MHz). On this band, as the PTO 
>>> frequency goes up, the TX/RX frequency goes down.
>>> 
>>> On 10 meters position A, the PTO (5.0 to 5.5 MHz) adds to the 13.99 MHz 
>>> crystal (the same crystal used on to produce 30 meters) to produce  19.99 
>>> to 21.49 MHz. The  the 9.0 MHz IF is added to this signal to receive the 
>>> incoming signal (27.99 to 28.49 MHz). On this band, as the PTO frequency 
>>> goes up, the TX/RX frequency goes up.
>>> 
>>> On 10 meters position B, the PTO (5.0 to 5.5 MHz) adds to the 14.49 MHz 
>>> crystal to produce  19.49 to 19.999 MHz. The  the 9.0 MHz IF is added to 
>>> this signal to receive the incoming signal (28.49 to 28.999 MHz). On this 
>>> band, as the PTO frequency goes up, the TX/RX frequency goes up.
>>> 
>>> On 10 meters position C, the PTO (5.0 to 5.5 MHz) adds to the 14.99 MHz 
>>> crystal to produce  19.99 to 20.49 MHz. The  the 9.0 MHz IF is added to 
>>> this signal to receive the incoming signal (28.99 to 29.49 MHz). On this 
>>> band, as the PTO frequency goes up, the TX/RX frequency goes up.
>>> 
>>> On 10 meters position D, the PTO (5.0 to 5.5 MHz) adds to the 15.49 MHz 
>>> crystal to produce  20.99 to 21.49 MHz. The  the 9.0 MHz IF is added to 
>>> this signal to receive the incoming signal (29.49 to 29.999 MHz). On this 
>>> band, as the PTO frequency goes up, the TX/RX frequency goes up.
>>> 
>>> In all cases, the counter simply corrects its preset to give the correct 
>>> readout. An analog dial would need a dual scale to work with this scheme. 
>>> The only difference is that the knob goes the opposite direction on the 
>>> higher bands than on the lower bands.
>>> 
>>> 40 meters SHOULD tune the same direction as 160…
>>> 
>>> One other error in the schematic is that the local oscillator is shown 
>>> connected directly to the FET power supply line (regulated as well) and 
>>> bypassed to ground via a 0.01 uF capacitor. This can’t work…
>>> 
>>> Gary
>>> W0DVN
>>> 
>>> 
>>>> On Aug 26, 2018, at 2:07 PM, Duane - N9DG via TenTec 
>>>> <tentec@contesting.com> wrote:
>>>> 
>>>> 
>>>> 
>>>> A test that would be interesting to see is if the behavior of how the CW 
>>>> signals tune behaves the same way when the mode switch is set to SB-N and 
>>>> then SB-R. They should behave differently from each other, one should tune 
>>>> like you expect CW to tune. And the other the way you now see CW tune.
>>>> 
>>>> If SB-N and SB-R behave as expected then there's a very good chance that 
>>>> one of the connections between the Mode switch and DSB board is not making 
>>>> the needed connection when in CW mode. In any case it would be well worth 
>>>> the time and effort to check the interconnection wire connections between 
>>>> the Mode switch and the DSB board.
>>>> 
>>>> After looking at the block diagrams and schematics it looks like that CW 
>>>> should tune as if the radio is in CW-N, if the mode is set to CW-R it 
>>>> should tune the opposite way, and the way you are describing.
>>>> 
>>>> So the suggestion that the problem is in the Double Sideband Board (DSB), 
>>>> or the wiring to it, I think is correct. But it should be noted that in 
>>>> the Corsair II there is just one crystal that is placed above and below 
>>>> the IF filter passband by capacitor that is switched into the BFO 
>>>> oscillator circuit by the positions on the Mode switch. And in the case of 
>>>> the CW tuning the wrong direction is because that crystal is not running 
>>>> at the right frequency.
>>>> 
>>>> So the issue is not related to the PTO or the LO oscillator mixer boards.
>>>> 
>>>> Duane
>>>> N9DG
>>>> 
>>>>> On Aug 25, 2018, at 12:17 PM, Paul DeWitte <k9ot@yousq.net> wrote:
>>>>> 
>>>>> I am not sure how to explain my problem.
>>>>> 
>>>>> I have 3 corsair IIs. recently I got one out to give it some air time. It
>>>>> had been a while since it had been used.
>>>>> 
>>>>> When tuning in a signal on 40M I found that instead of turning the VFO
>>>>> CLOCKWISE to zero beat on a low pitch signal, I have to go down (counter
>>>>> clockwise) to get on frequencey. The offset tuning works the same way. I
>>>>> have to tune down to bring the signal up in pitch.
>>>>> That is exactly backwards of how TT radios work on 1.8 to 10 MHZ.
>>>>> 
>>>>> Everything else seems to be correct. The frequency readout seems  to be
>>>>> correct as you tune up the band.It has good rcv audio, and this is the 
>>>>> only
>>>>> thing that I find wrong.
>>>>> 
>>>>> Is there  a wiring problem here? In looking at one of the others, I do not
>>>>> see any difference in wire routing.
>>>>> Can it be the PTO?
>>>>> 
>>>>> Thanks for any replies,
>>>>> 73 Paul K9OT
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