Just noticed this evening that on 160 I lose about 6 dB of rx level (noise and
signal ) when I go from STDBY to OPER. On 40 maybe a dB or so , on 20 no change
-- On160 almost always am using RX antenna so am not going thru the KPA but
this evening had Tx ant on RX .
Maybe has always been that
There was a similar report fairly recently. I copied this to my KPA500 notes:
"Reported problem(s):
Receive signal is attenuated when in operate. Receive signal is normal when
in standby.
Problem(s) found:
Confirmed problem. Found that D8, D9 and R7 in the T/R circuit had failed.
Repair(s) perf
Greetings, this is my first approach to the qth.net.
My K-3, assembled from the factory, quite a few years ago, shows the very
first failure,
it does not turn on. Voltage at the power socket is 13.5VDC.
Where shall I look?
Vy 73
Antonio - CU8AS
_
This happened with my backup amp at the contest station on J6. I left it
connected by accident overnight (too much rum) and we had some static
storms. Took out the pin diodes (well, more accurately the diodes that act
like PIN diodes). When put in operate, the receive drops by 30+ dB but
still t
Would a gas discharge tube save the sensitive parts?
David G3UNA
> On 05 June 2021 at 16:20 "Dr. William J. Schmidt" wrote:
>
>
> This happened with my backup amp at the contest station on J6. I left it
> connected by accident overnight (too much rum) and we had some static
> storms. Took o
I'm sure you could invent many ways to protect these parts (gas tubes,
sacrificial TVS diodes, fusing, etc.). The best way, of course, is to
disconnect it (which of course I did not do). These are low voltage parts on
the receive side path so I don't know if a gas tube would be appropriate
he
Does that confirm correctness, or brokenness?
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 6/5/21 8:20 AM, Dr. William J. Schmidt wrote:
This happened with my backup amp at the co
This doesn’t really have the signature of pin-diode failure. When the pin
diodes fail you generally get major signal loss across all bands. The
description simply does not match that diagnosis.
I would ask for further information:
* Is there any change in 160m transmit operation (change in drive
Even (sub) nano second (ns) fast acting gas tubes are primarily not a safe
solution to RX front end burnout protection.
Semiconductors:
Issues: Energy Protection level, RX Intermodulation prevention.
There are however some fast semiconductor diodes (ESD protection) available
with low capacitance
Hi Antonio,
Am 05.06.21 um 16:23 schrieb Antonio Madeira:
> Greetings, this is my first approach to the qth.net.
>
> My K-3, assembled from the factory, quite a few years ago, shows the very
> first failure,
> it does not turn on. Voltage at the power socket is 13.5VDC.
>
> Where shall I look?
C
Good Evening,
This week was sunny and hot. Plants and insects grew very well. I
was able to build three antennas but only raised one of them. I am coax
challenged. A few more runs plus an antenna switch will be on order
soon. Four antennas should give me paths into much of North Americ
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