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Something different this time...


Brian L. Davis
 

I've seen some odd things but this is one of the oddest.
I have experienced intermittent receive and transmit, just momentary that seemed to be cable related.
Traced it to the BNC jack.
Seems the female socket in the jack is slightly oversize and the male pin was a loose fit and occasionally showed an open circuit.
Changed the jack and the problem went away.


Jim Sheldon
 

It isn't really odd at all.  It's just that their supplier has gotten some very poor quality BNC connectors.  I've had 3 of them with the larger center pin that would not make good contact.  Replaced them all with Amphenol BNC connectors from Digi-Key.  It appears the Chinese can't measure things right when they make these things!  Fortunately, it was readily noticeable on receive.  However, I have transmitted into opens a number of times, high SWR antennas several times and still have intact IRF 510's.  I firmly believe the IRF 510 problem is caused by poor quality (Fake) IRF 510's, not transmitting into opens, shorts or somewhere in between! 

Jim - W0EB

------ Original Message ------
From: "Brian L. Davis" <brianldavis@...>
Sent: 4/29/2018 5:23:30 PM
Subject: [BITX20] Something different this time...

I've seen some odd things but this is one of the oddest.
I have experienced intermittent receive and transmit, just momentary that seemed to be cable related.
Traced it to the BNC jack.
Seems the female socket in the jack is slightly oversize and the male pin was a loose fit and occasionally showed an open circuit.
Changed the jack and the problem went away.


Ryan Flowers
 

This is the very reason I switched to PL259/SO239 connectors. 

--
Ryan Flowers - W7RLF
MiscDotGeek.com
Multi Band BITX40
The BITX40 FAQ


William R Maxwell
 

it might have been a 75 ohm BNC socket?


On 30/04/2018 11:23 AM, Jim Sheldon wrote:
It isn't really odd at all.  It's just that their supplier has gotten some very poor quality BNC connectors.  I've had 3 of them with the larger center pin that would not make good contact.  Replaced them all with Amphenol BNC connectors from Digi-Key.  It appears the Chinese can't measure things right when they make these things!  Fortunately, it was readily noticeable on receive.  However, I have transmitted into opens a number of times, high SWR antennas several times and still have intact IRF 510's.  I firmly believe the IRF 510 problem is caused by poor quality (Fake) IRF 510's, not transmitting into opens, shorts or somewhere in between! 

Jim - W0EB

------ Original Message ------
From: "Brian L. Davis" <brianldavis@...>
Sent: 4/29/2018 5:23:30 PM
Subject: [BITX20] Something different this time...

I've seen some odd things but this is one of the oddest.
I have experienced intermittent receive and transmit, just momentary that seemed to be cable related.
Traced it to the BNC jack.
Seems the female socket in the jack is slightly oversize and the male pin was a loose fit and occasionally showed an open circuit.
Changed the jack and the problem went away.


Jerry Gaffke
 

We've been over this before.
Likely a 50 ohm BNC connector.that was slightly out of mechanical spec.
And 75 ohm BNC connectors should mate just fine with 50 ohm BNC connectors anyway.
See post   https://groups.io/g/BITX20/message/39196


On Sun, Apr 29, 2018 at 06:55 pm, William R Maxwell wrote:

it might have been a 75 ohm BNC socket?


Jerry Gaffke
 

I'm genuinely curious, what IRF510 problem?
Is that from posts to this forum?
Can you point to such a post?

I have heard of counterfeit IRF510's being sold on ebay.
I'm not aware of hfsignals having trouble with bad IRF510's.

Jerry


On Sun, Apr 29, 2018 at 06:23 pm, Jim Sheldon wrote:
I firmly believe the IRF 510 problem is caused by poor quality (Fake) IRF 510's, not transmitting into opens, shorts or somewhere in between!