Pete;
If you get the reference oscillator on frequency and the BFO is off then the
digital display will also be off frequency.
The reason I keep mentioning this is that I’ve seen no evidence other than your
statement “the BFO’s are working correctly”.
I do not agree modifying the circuit will be a solution. From experience
having owned 2 different Paragon radios and repairing many many of these with
various issues, this is a 40 year old radio and design. If one ends up with a
+/- 100 Hz error, I’d stop tweaking.
Bob, K4TAX
Sent from my iPhone
> On Oct 25, 2020, at 8:00 PM, Pete Ferrand <petef@sprynet.com> wrote:
>
>
>
>>
>> The reference oscillator frequency is not related to the BFO oscillators.
>
> I never said it was, you mentioned it and the BFOs are working correctly. The
> reference oscillator is off frequency, hence the subject in the email. I want
> to fix that.
>
> This may be due to age, someone's replacement part, or perhaps it was off
> from the factory, whatever.
>
> My point is yes, the likely problem is the 42 MHz crystal. However, there is
> no way to order an crystal meeting Ten-Tec's spec because they never
> published a spec. Therefore the new one may be 200 Hz off as well, or a lot
> more. That is why modifying the circuit would be far easier and that is what
> I asked for help with.
>
> Pete
>
>
>
>>
>> The BFO is 2 crystals which are trimmed by 4 switched trimmers. From
>> experience, the BFO adjustments do have some interaction with each other,
>> thus the reason for going over the sequence a couple of times.
>>
>> If the reference oscillator won’t come on frequency then either a component
>> has changed value due to age and this includes the 42MHz crystal.
>>
>> Bob, K4TAX
>>
>>
>> Sent from my iPhone
>>
>>>> On Oct 25, 2020, at 7:20 PM, Pete Ferrand <petef@sprynet.com> wrote:
>>>
>>>
>>> Thanks for responding you guys but I don't think you understood what I'm
>>> saying.
>>>
>>> I can't leave the reference oscillator at 84 MHz because it's not at 84
>>> MHz!
>>>
>>> The best I can do is adjust it to 300 Hz lower in frequency than 84 MHz.
>>> The specs call for plus/minus 5 Hz. I thought this was clear.
>>>
>>> Why do you guys want me to start with the BFO adjustments?
>>>
>>> I've aligned dozens of Ten-Tecs and I've always followed the Ten-Tec
>>> alignment procedures, which call for starting by setting the reference
>>> oscillator.
>>>
>>> It seems absurd to tune the BFOs when the reference oscillator is off
>>> frequency!!!
>>>
>>> Hence, I need to simply add frequency to the crystal. About 200 Hz would do
>>> it.
>>>
>>> This is the problem. When the reference is correct the rest of the
>>> USB/LSB/CW/FM tuning is perfectly fine. But the reference oscillator can't
>>> be put on frequency.
>>>
>>>
>>>
>>> Thanks.
>>> Pete
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>>> From: "Bob, WB2VUF via TenTec" <tentec@contesting.com>
>>>> Sent: Oct 25, 2020 6:20 PM
>>>> To: Discussion of Ten-Tec Equipment <tentec@contesting.com>, Bob McGraw
>>>> K4TAX <rmcgraw@blomand.net>
>>>> Cc: "Bob, WB2VUF" <wb2vuf@verizon.net>
>>>> Subject: Re: [TenTec] Paragon Reference Oscillator
>>>>
>>>> I agree. Leave the reference oscillator exactly at 84 MHz and align the
>>>> BFO crystals instead. They are the most likely to be off frequency.
>>>> Yes, they must be adjusted in sequence as indicated in the manual.
>>>>
>>>> 73,
>>>>
>>>> Bob WB2VUF
>>>>
>>>>> On 10/24/2020 11:23 AM, Bob McGraw K4TAX wrote:
>>>>> The first thing to check is the oscillators on the Transmit Audio/BFO
>>>>> Board. The procedure is on page 6-65 of the manual. From experience,
>>>>> the adjustments are somewhat interactive and must be done in the order
>>>>> as listed. You should go through the procedure at least twice. Be
>>>>> sure the radio has been on for 1 hr to allow the temperature to
>>>>> stabilize as the crystals are subject to drift with temperature.
>>>>>
>>>>> As to the 42 MHz crystal, it may have aged to the point that it will
>>>>> not be in the range needed. Replacement is the most likely option.
>>>>>
>>>>> 73
>>>>>
>>>>> Bob, K4TAX
>>>>>
>>>>> On 10/24/2020 2:54 AM, Peter Ferrand wrote:
>>>>>> I have a new-to-me Paragon 585.
>>>>>>
>>>>>> The rig is slightly off frequency from its readout and the best I can
>>>>>> do is adjust the reference oscillator with C1 to 300 Hz lower in
>>>>>> frequency than the 84 MHz it's supposed to be. Ten-Tec specifies this
>>>>>> frequency must be plus or minus 5 Hz at 84 MHz, which is the output
>>>>>> of the frequency doubler.
>>>>>>
>>>>>> I tried removing or reducing C2 but the oscillator stops oscillating.
>>>>>> Rather than track down a new 42 MHz crystal, I wonder if anyone with
>>>>>> more design skills than I have can suggest a slight redesign of the
>>>>>> circuit to pull the existing crystal higher.
>>>>>>
>>>>>> Thanks.
>>>>>> Pete
>>>>>> WB2QLL
>>>>>> Mount Pleasant, WI
>>>>>>
>
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