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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: Bob McGraw K4TAX <rmcgraw@blomand.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 26 Aug 2018 20:21:38 -0500
List-post: <mailto:tentec@contesting.com>
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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