Hi Lyman,
I don't know why do you have that funny reading on 10 MHz. I have
never studied the heterodyne VFO topology or which corrections is the
frequency counter making depending on the selected band.
My feeling is that the frequency counter module is applying the same
settings that correspond to the 10 meter band.
There is a brief description here on how the Corsair works (not
exactly your radio, but not a distant relative either)
http://www.radiomanual.info/schemi/Vari/Ten-Tec_Corsair_560_review_1984.pdf
73,
Carlos VK1EA
On 1/3/19, forum4ll@verizon.net <forum4ll@verizon.net> wrote:
> Carlos, et al.
>
> After removing the magenta power wire from the logic board, the tone
> was gone! So it is the frequency counter. I then checked the 1000mfd cap and
> it tested fine for capacitance, ESR, and leakage. I disconnected C2, 560pf,
> that connects pin 16 of MK50398N to Vcc. The tone was gone. The receiver
> is working fine but in my haste in putting it back together, I was off by
> one
> pin on the Preset Amp board to Display Board connection. The frequency
> meter was reading weird. Correcting that, all the bands appeared fine except
> the 10mhz band. It is picking up WWV on 10 mhz but it reads 28.0 mhz.
> The whole band now read 28.0 to 28.5mhz instead of 10 to 10.5mhz.
>
> I need to check the components on the Preset Amp board. Any suggestions
> are welcomed.
>
> Lyman KK6LPW
>
>
> -----Original Message-----
> From: forum4ll <forum4ll@verizon.net>
> To: tentec <tentec@contesting.com>
> Sent: Tue, Jan 1, 2019 12:05 pm
> Subject: Re: Omni-D with an Annoying 1khz Tone
>
> Carlos,
> I will do that when I get into the shop tomorrow. From your suggestion,I
> found these two other things I can look for in the frequency counter:
> 1. https://www.eham.net/ehamforum/smf/index.php/topic,26529.0.html
> 2. The digital whining from DL1CYP's Ten-Tec 544:
> https://www.eham.net/reviews/detail/735?page=2
>
> Thanks,
> Lyman, KK6LPW
>
> *************************************************************************************
> mmm... digital noise from the frequency counter?
>
> Can you cut the DC suply to that module and tell us what happens?
>
>
> 73,
> Carlos VK1EA
>
> On Tuesday, January 1, 2019, <forum4ll@verizon.net> wrote:
>>
>> Happy New Year everyone!
>>
>> This Omni-D that I've been working has an annoying tone that can be heard
> across all bands and it is in the background. It measures about 1khz and
> will vary harmonically when I slowly turn the VFO thus changing the 100s
> hertz digit in the display. The waveform changes back and forth between a
> sinusoidal and a rough sawtooth. I can mask this tone by turning up the Rf
> gain but its still there. It is pronounce when the Rf gain is turned down.
>>
>> Does anyone know what the problem might be? Could it be in the VFO or
> possibly the IF section?
>>
>> Lyman KK6LPW
>
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