Circuit Board Specialists Kit
 

I recently came across an unbuilt kit from the subject company. It is
for a "Universal QRP Transmatch". The front panel measures 2 3/4 by 5
and is etched from circuit board material and has the ARRL logo either
side of the controls. Unfortunately, I have no assembly instructions but
I do have the invoice and know that it was shipped on 3/12/82. I search
of ARRL publications for the previous 10 years produced no match but the
QRP transmatch article in QST for October 1973 may have been the
inspiration.

The QST design used 3 toroidal tapped inductors but there is just one
core in the kit. Both designs used a 12 position switch to select the
inductance. As I seem to be missing any knobs that would fit the
miniature variable capacitors, I may also be missing the other cores but
I don't think think so. I am at a bit of a loss with regard to the
inductance winding specs though I guess I could eventually find
something that works by trial and error.

Does anyone have any info on this kit? Or on Circuit Board Specialists?
They don't seem to be in business anymore from what I can tell.

Thanks in advance. If you wish to reply direct, remove the obvious extra
element from my email address.

73, CJ K0CJ

sounds like a BLT .Do a google search you should find some info.

sounds like a BLT .Do a google search you should find some info.

sounds like a BLT .Do a google search you should find some info.

The Norcal BLT (which is what I believe you're referring to) is a
Z-match type of tuner. It uses a single toroid to create a coupling
link between the unbalanced input and the balanced output.

The BLT's toroid is wound with a single primary (having a single fixed
tap), and a pair of secondaries for low- and high-impedance loads. It
does _not_ have the sort of multiply-tapped-and-switched coil
architecture that the original poster alluded to - these are usually
used in unbalanced-configuration T and L tuners. The tuning is done
with the two capacitors (a series input cap, and a cap which shunts
the primary toroid winding), and via a DPDT switch to select the
appropriate secondary winding.

I don't know whether the OP's components and kit were originally
intended for a multiply-tapped-inductor T tuner, or for a Z-match such
as the BLT, but it sounds likely that they could probably be adapted
to either (possibly with the addition of a few extra junkbox
components).

I built a Norcal BLT a few months ago, and I've been quite happy with
it... it's a nice little QRP design especially when modded to support
coax-fed unbalanced antennas (add one BNC jack and one SPST switch).
The lack of multiple inductor taps and a tap-selection switch is a
definite plus, convenience-wise. It seems to tune my tri-wire fan
dipole to off-resonant frequencies just as effectively as my big QRO
tuner (based on the Ultimate Transmatch design, according to the guy
who built it).

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

sounds like a BLT .Do a google search you should find some info.

The Norcal BLT (which is what I believe you're referring to) is a
Z-match type of tuner. It uses a single toroid to create a coupling
link between the unbalanced input and the balanced output.

The BLT's toroid is wound with a single primary (having a single fixed
tap), and a pair of secondaries for low- and high-impedance loads. It
does _not_ have the sort of multiply-tapped-and-switched coil
architecture that the original poster alluded to - these are usually
used in unbalanced-configuration T and L tuners. The tuning is done
with the two capacitors (a series input cap, and a cap which shunts
the primary toroid winding), and via a DPDT switch to select the
appropriate secondary winding.

I don't know whether the OP's components and kit were originally
intended for a multiply-tapped-inductor T tuner, or for a Z-match such
as the BLT, but it sounds likely that they could probably be adapted
to either (possibly with the addition of a few extra junkbox
components).

I built a Norcal BLT a few months ago, and I've been quite happy with
it... it's a nice little QRP design especially when modded to support
coax-fed unbalanced antennas (add one BNC jack and one SPST switch).
The lack of multiple inductor taps and a tap-selection switch is a
definite plus, convenience-wise. It seems to tune my tri-wire fan
dipole to off-resonant frequencies just as effectively as my big QRO
tuner (based on the Ultimate Transmatch design, according to the guy
who built it).

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!