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Re: [TenTec] Omni V I Assistance Needed

To: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Subject: Re: [TenTec] Omni V I Assistance Needed
From: Byron Cordes via TenTec <tentec@contesting.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 29 Sep 2018 19:00:06 -0500
List-post: <mailto:tentec@contesting.com>
I’ll have to pull filter ,good idea . Let you know  tomorrow . Thanks 

Sent from my iPad

> On Sep 29, 2018, at 6:21 PM, MadScientist <dukeshifi@comcast.net> wrote:
> 
> OK, I am involved in three threads regarding Paragons, Omni 5’s and Omni 6’s 
> so I have gotten some crosstalk…
> 
> If you select a filter position on your radio that has no filter in it, do 
> you still hear the clicking sound when tuning?
> 
> Gary
> 
>> On Sep 29, 2018, at 5:33 PM, Byron Cordes via TenTec <tentec@contesting.com> 
>> wrote:
>> 
>> The radio is a Omni VI.  Radio does rx and tx . can here and talk to people 
>> even on 20 meters where that vfo noise is . Higher noise floor on 40- 160 
>> you don’t here the vfo noise but on 20 meters it is very loud higher than 
>> the people talking when tuning . Stop turning vfo and radio sounds normal 
>> with people talking .
>> 
>> Sent from my iPad
>> 
>>> On Sep 29, 2018, at 5:23 PM, MadScientist <dukeshifi@comcast.net> wrote:
>>> 
>>> Sorry, I misread… I was focussed on a previous radio (a Paragon).
>>> 
>>> Your problem is most certainly due to the fact that the 5.0 to 5.5 MHz PLL 
>>> is going out of lock. This model does not produce any out-of-lock fault 
>>> regardless of the lock condition of the PLL so it can be out-of-lock with 
>>> no indication of that condition. The radio will still produce normal band 
>>> hiss but you will not be able to tune in signals.
>>> 
>>> Oddly, he radio will still transmit in this condition, but well out of the 
>>> Ham bands! It will transmit on the frequency at which the VCO settles when 
>>> out-of lock, about 14.6 MHz, regardless of dial setting or display readout 
>>> reading. It will also be very unstable.
>>> 
>>> From what you describe (now that I am on the right page model-wise) i would 
>>> suggest replacing the dual gate MOSFET in the loop IF. 
>>> 
>>> I recently repaired an Omni 6 that had the same problem as your Omni 5 has. 
>>> That FET was the culprit and what’s worse, it pulled the alignment due to 
>>> leakage of the device. It was highly intermittent. The heat/cool method was 
>>> the only way I could point to it, but monitoring the loop test point was 
>>> the only way I could prove it to myself.
>>> 
>>> The way to really determine if this is the fault is to put a voltmeter on 
>>> the 10K resistor test point of the loop IF (That resistor stands up on the 
>>> board whereas all of the others lie down, and the test point is the high 
>>> end of that resistor (thankfully). Then, from a cold start of the radio, 
>>> monitor that voltage as the warmup progresses. While the PLL will lock with 
>>> as little as 80 mV at t his point, it will be unstable. You SHOULD get, as 
>>> I said, >300 mV at all three band test frequencies.
>>> 
>>> The actually band selection is not important because this PLL operates the 
>>> same regardless of band. However, an exception exists in that the PLL will 
>>> not tune to “500” position on 40 meters.
>>> 
>>> Also, the PLL tunes in opposite directions on low bands and high bands. 
>>> That is why I chose 20 meters to select which coil to peak at what 
>>> frequency.
>>> 
>>> I used a BF988, available from Littediode on eBay to replace the loop IF 
>>> FET. The devices I get for Littlediode always work so they are a safe 
>>> seller IMHO.
>>> 
>>> You may need to align the loop IF if you do not get at least 300 mV DC on 
>>> the loop IF test point on all portions of the band (14.000, 14.250 and 
>>> 14.500) since this is a broadly tuned LC IF stage that was likely 
>>> originally aligned using a sweep generator.
>>> 
>>> I approximated the sweep generator by aligning the three IF coils, one a 
>>> tach frequency test point. The left most I peaked at 14.200, the middle one 
>>> at 14.250 and the right most one at 14.500 (radio on 20 meters, of course).
>>> 
>>> Gary
>>> 
>>>> On Sep 29, 2018, at 3:42 PM, Dry Martini Holding Company😎 <qrp@kg4kgl.net> 
>>>> wrote:
>>>> 
>>>> I have a similar issue with my V.9. When I first turn it on, it will be 
>>>> fine then recv audio will drop out. If I leave it on for 15 or 20 min, 
>>>> recv audio becomes normal again and is fine the rest of the day. 
>>>> st point
>>>> I sent mine to steve Yudell in Florida and he had it for a couple of weeks 
>>>> and it worked fine for him after he went through it. Now that I have it 
>>>> back it has started doing it again. I just don’t feel like boxing it up 
>>>> and sending it back. I am just going to live with it. 
>>>> 
>>>> If you find out what the problem is, let me know. 
>>>> 
>>>> Robert 
>>>> KG4KGL 
>>>> 
>>>>> On Sep 29, 2018, at 15:40, arsn4dd@charter.net wrote:
>>>>> 
>>>>> Is there an Omni V mechanic in the house? My radio is going to need
>>>>> one if it doesn't straighten up... HI HI 
>>>>> I have a very sparingly-used Omni V.9 that has developed an
>>>>> intermittent receive issue. From a cold start, the radio powers up and
>>>>> operates properly. After some random period of time, I can power cycle
>>>>> the radio, and as a result, I lose receive signals. I retain plenty of
>>>>> audio, and plenty of what sounds like band noise, but there no signals
>>>>> anywhere. I can leave the radio off for a couple of minutes, power it
>>>>> up, and the signals return. Before the suggestion is floated, I have
>>>>> exercised every connection in the radio with DeOxit. I have tightened
>>>>> and re-tightened every screw on every board in the radio. I have not,
>>>>> however re-seated any of the chips. Is there enough information here
>>>>> to generate suggestions? I admit to being mostly an appliance
>>>>> operator, but I might be capable of doing a few diagnostics. Thanks in
>>>>> advance for any guidance. 
>>>>> Best Regards to all!
>>>>> Dennis N4DD
>>>>> _______________________________________________
>>>>> TenTec mailing list
>>>>> TenTec@contesting.com
>>>>> http://lists.contesting.com/mailman/listinfo/tentec
>>>>> 
>>>> 
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