Lots of good suggestions already posted.
Don’t overlook the possibility of a heat-induced failure of a capacitor or
anything else that could affect final amplifier or driver bias. Improper bias
can cause LOTS of harmonic distortion and, into a resonant load, presents a
high SWR. Try testing the radio, when it is acting up, into a resistive dummy
load to see if this kills the high SWR. Since the dummy load is not resonant,
the harmonics from the radio will not appear as reflected power so no elevated
SWR will be seen.
Gary
W0DVN
> On Jan 1, 2020, at 11:58 AM, Bob McGraw K4TAX <rmcgraw@blomand.net> wrote:
>
> Yes, coax jumpers do go bad from all the wiggling and jiggling, connecting
> and disconnecting. And some are just pure crap to start with.
>
> Also any PL-259 must be more than finger tight. I use a pair of 4" Channel
> Lock pliers to snug mine. That solves many many problems.
>
> I use my antenna bridge on 144 MHz and a dummy load to test my jumpers. I
> wiggle, jiggle, pull and push. If the SWR flickers, I chop the PL-259 off
> and start with a new piece of coax and a new connector. It isn't worth
> trying to save a questionable connector or piece of coax.
>
> 73
>
> Bob, K4TAX
>
> On 1/1/2020 11:32 AM, Byron Cordes via TenTec wrote:
>> Let’s hope for the best. Bad coax jumper Bad pl259 antenna , ground
>> connection on antenna . Do you have different antenna ?
>> I just had a bad coax a few months ago.
>> 73s Byron AC9PA
>>
>> Sent from my iPad
>>
>>> On Jan 1, 2020, at 11:13 AM, 1291jim@gmail.com wrote:
>>>
>>> Happy New Year All,
>>>
>>> I have had an issue with my Eagle happen twice now.
>>>
>>> Issue:
>>> - Eagle loses tuning and SWR starts going crazy and jumping all over the
>>> place
>>> - Will not tune with inboard or outboard tuner
>>> - Returns to normal operation after I shut in down for a while
>>>
>>> Background:
>>> - Has only happened when I have been operating for several hours and during
>>> a 20 min+ QSO, (so lots of sending) and both times on 40M
>>> - Eagle felt warm but not hot
>>> - Antenna is an EndFed (Alpha Antenna J-Pole Sr)
>>> - Without tuning on 40M SWR is 2.6 : 1
>>> - Normally tunes to 1.0 or 1.1 : 1 with outboard or internal tuner
>>>
>>> 1st occurrence:
>>> - I had been operating for 3-4 hrs
>>> - Eagle was running 100W through an MFJ Intellituner Model 993B that tuned
>>> SWR to 1.1 : 1
>>> - SWR started jumping all over the place
>>> - MFJ could not tune it
>>> - I assumed it was the MFJ Tuner, shut it all down.
>>>
>>> 2nd occurrence: (last night)
>>> - Had been operating several hours at 100W
>>> - Eagle again through MFJ Tuner when SWR started jumping all over
>>> - This time I bypassed the MFJ tuner and tried to tune with the Eagles
>>> internal tuner
>>> - The internal tuner could not tune the antenna and SWR continued going nuts
>>> through the attempted tuning process
>>>
>>> This morning after a rest, rig tunes FB with outboard or inboard tuner.
>>>
>>> Pulling it from service now.
>>>
>>> Any advice would be appreciated.
>>>
>>> HNY ES 73 DE W6JIM
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>>> TenTec@contesting.com
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