Re: QBSA - Changes /Mods ??
Please see Steve's post # 851 as well as # 592 & # 864 (per Mike M1MT).
If your QBSA kit is recent, you may not need to worry about the display
freezing (#851), since Steve fixed the firmware.
If you know what you're doing and like taking risks, you can modify
your QBSA to give a maximum output of 12V instead of 11V. This will
let the ATS rig deliver close to 5W, but it's risky. Steve chose 11V
for a reason - he doesn't want you to damage your rig. If you run on
12V, you must have an accurate 50 ohm load (which the QBSA will tell
you). It's also smart to do any tuning of antennas or matching
networks at low voltage. Use a tuner like the BLT that has a resistive
bridge, so your ATS rig is not subjected to severe mismatch during
tuning. Read the relevant parts of Steve's ATS manual carefully.
I have a post in the FILES section describing a way to get 12V from the
QBSA, but if you understand 3-terminal regulators like the LM317T, you
just change the components in the ADJ terminal circuit to get what you
want. You can tailor the voltage range as you like. If you run on
12.0V, you'll need to supply 15.0V or more (under full load) to the
QBSA power input to avoid regulator dropout. You should check for
There also are keying issues discussed on numerous other posts here.
The keying issues get worse as the supply voltage is raised above 11V,
and I don't recommend you run on 12V, unless you modify the keying
circuit in your rig.
These various mods are slightly technical, so you probably should just
leave everything the way Steve intended, unless you like tweaking
things and have perfectionist tendencies.
The QBSA is a really nice unit and an amazing value for the features it
provides. I put mine in an extra BLT case I happened to buy when they
were still available separate from the BLT. It is quite snug in
there. There is more work required to drill and fit the case than to
assemble the QBSA itself. Plan your case construction somewhat before
you start soldering your QBSA.
I think you'll be delighted with your QBSA if you work carefully!
Good luck - 72/73
--- In AT_Sprint@yahoogroups.com, "phm7744" <pmeier@...> wrote:
> Hi all,
> I'm about to start construction of the QBSA kit. Are there changes or
> mods I should consider adding while I build (ones not indicated in
> original pdf manual) ?
> Pete WK8S