[TenTec] Paragon Reference Oscillator

[Pete Ferrand]

>
>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 at 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
>> 
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>> 
>> -----Original Message-----
>>> From: "Bob, WB2VUF via TenTec" <tentec at contesting.com>
>>> Sent: Oct 25, 2020 6:20 PM
>>> To: Discussion of Ten-Tec Equipment <tentec at contesting.com>, Bob McGraw K4TAX <rmcgraw at blomand.net>
>>> Cc: "Bob, WB2VUF" <wb2vuf at 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
>>>>>