[TenTec] Issues aligning Omni 6+ (Mod. 564) FM TX carrier frequency
Bob McGraw K4TAX
rmcgraw at blomand.net
Tue Nov 6 11:06:09 EST 2018
Component aging including crystal. Tweak the fixed value of the C in the Oscillator. Still the HF Osc for a given band may need adjusting.
Sent from my iPhone
> On Nov 6, 2018, at 9:42 AM, Sven Ladegast via TenTec <tentec at contesting.com> wrote:
> Hello Bob,
> Many thanks for your answer! - I did the BFO alignment already and all BFO frequencies are okay, even CW TX is set to 9.00300 MHz.
> Because there is no BFO in mode *FM*, the carrier is produced by a separate XTAL on the FM board. This XTAL drives a Colpitts oscillator and is tuned by a trimmer coil L2. I cannot get this single frequency aligned. The maximum frequency with the core fully turned out of the coil is 8.9965 MHz and so my FM TX carrier is always almost 1.5 kHz off the RX.
> Though I do not use FM very often, it would be nice if the radio does work completely!
> vy 73!
> Sven, DJ2AT
> Am 06.11.2018 16:34, schrieb Bob McGraw K4TAX:
>> Perform the BFO alignment in the sequence defined in the manual. All
>> steps must be done regardless of the mode you operate or do not
>> operate. Be sure the radio is up to operating temp. Perform the
>> sequence 2 or 3 times as there is interaction between the adjustments.
>> The set the Master Osc so the radio displays the correct frequency.
>> The display is not a true frequency measurement but is a display based
>> on the Master Osc. It does not know if the band Oscillator is off
>> frequency. Also you can trim each band to get the frequency per band a
>> bit closer.
>> Bob, K4TAX
>> Sent from my iPhone
>>> On Nov 6, 2018, at 9:04 AM, Sven Ladegast via TenTec <tentec at contesting.com> wrote:
>>> Hello folks,
>>> I do have trouble aligning the TX carrier frequency on an Omni 6+.
>>> With no modulation applied, the TX carrier frequency shall be 9.00300 MHz measured at connector 73 of the board. I used a TMP-BNC cable and connected it to connector 73 and connected the BNC connector to my accurate frequency counter using a T-connector and additional 50 Ohms termination.
>>> The TX carrier frequency is aligned by turning the core of L2 but with the core complete turned out of the coil I get a maximum frequency of 8.9965 MHz and cannot get to 9.00300 MHz. Do have anyone an idea what is going wrong? Aged XTAL?
>>> Sven, DJ2AT
>>> TenTec mailing list
>>> TenTec at contesting.com
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