Re: Good news, then not so good...
- Yes, around 90ma draw on receive is about right. It would be very
hard to help at this point, leave the power on and try to find a warm
part. After that it takes some real problem solving techniques that
are hard to cover here.
I just finished 2 hours of contacts making the board not-cold to
touch, nothing on the bottom is warm, only the top area around R19 and
the PTT and serial area are slightly warm. Bill k6acj
--- In firstname.lastname@example.org, "Mike" <mike@...> wrote:
> --- In email@example.com, "Bill P." <k6acj@> wrote:
> > Something should be warm if the measurements are correct.
> The normal current draw -was- 90 Ma; It is now 160 Ma. (Not too much
> Remove the
> > PA module does the currant draw change? Check the PA heat sink and
> > measure the voltage drops across R210 & R211, the 2.1 ohm source
> > resistors on each FET. Shoud be 55mv drop. Maybe one of the
> > resistors shows higher drop therefore the FET associated FET is bad.
> No added current is being drawn by the PA/Filter.
> (The 160 Ma current draw remains the same, no matter if the receive
> bandpass filters or if the PA/Filter boards are installed or not.
> > If the SR is still drawing high currant without the PA module, then it
> > gets more difficult but suspect a solid state device internally
> > shorting to ground if there are no circuit board shorts.
> This is what I am afraid of...
> A bit of history:
> - The unit initially drew about 90 Ma in receive.
> - It now draws about 160 Ma in receive.
> - The PA/Filter and the receive bandpass boards are NOT installed.
> - I have never tried to transmit, yet.
> - The normal QSD and QSE signals are still present on the board.
> Using PowerSDR, the NOISE FLOOR was really, REALLY high!
> - The noise floor was well above S-9, even if the antenna inputs were
> shorted together.
> - The unit DID work at first. (For several hours.)
> - When the unit did work, BOTH of the PA/filter boards were installd.
> - The unit did receive, but it took a very BIG (S-9 + 10 to 20 dB)
> - I had a good I/Q output from the RXTX output to the computer, when
> it worked.
> - I no longer have the I/Q output, and PowerSDR is showing a very LOW
> level in the panoramic adapter.
> > 80/40 are sometimes dead in the evening , listen for WWV on 2.5, 5 or
> > 10Mhz or put your commercial gear on low power and perform a
> If I attach an antenna, I hear (and SEE) nothing.
> If I inject a signal from my service monitor, I hear (and see) nothing.
> > Sometimes the Software does not start correctly or if USB there can be
> > a problem, do a cold boot with all connections in place.
> No USB is being used at this time. I have only POWER, ANTENNA and the
> I/Q wires attached to the RXTX.
> Major question: Dare I use a DVM to look for shorts? Or, will this
> do damage to the ICs that are in place?????
> Related question: How do I locate the short or added load? (To
> resolve the issue.)
> Thank you! -Mike- K0JTA