[1000mp] Mark-V, Alpha 91b and Palstar AT4K

[Hans Remeeus]

It may be off topic, but some of us could be interested. If not; just hit
the <Delete> button.

I use the Palstar AT4K in combination with the FT-1000MP Mark-V and the
Alpha 91b linear. Class-A, 25 Watts (to prevent overloading I realigned
VR3006 and VR3007 from 75 to 25 Watts and set Menu 4-1 and 4-3 on 75 Watts
RF out). For interconnection between the Mark-V and 91b I use the Band Data
connector with a resistor of 100k.

1. The relay in the Palstar AT4K to switch the Tuned Output between Balanced
and Coax is (IMHO) good for in your Chevy but not for RF purposes! I only
use Balanced feederlines, so I bypassed this relay. When I want to use the
AT4K for coax I could always install a ground strap (jumper) between one
side of the Balanced Output and Ground.

2. My antenna (2 x 18 meters inverted Vee) is too short for 160 meters.
Nevertheless to get a correct tuning I installed a fixed capacitor (use
400-500 pF, advisable 8-14 kV) parallel with the Output variable capacitor
of 480 pF. The fixed capacitor is being switched (for 160 meters only) with
a vacuum relay (advisable 8 kV). To operate the vacuum relay you could use
the switch for the Tuned Output on the frontpanel of the AT4K. Use a
Labelmaker (white on black) to get the new indication of the frontpanel
switch. (LOW Z, in = 160 m., out = 80 - 10 m.)

3. Results on the 160 till the 20 meter band are excellent now! However I
don't get correct tuning on 17 till 10 meters.

The Palstar AT4K balance is poor on 10 meters and Palstar is not able to the
minimum capacitance of the 480pf variables below 19pf or so. Even though
they have retooled the stator and rotor plates with a slope to lower the
minimum from the original of 33pf to 19pf.

Also the minimum inductance is not low enough either. Palstar thinks they
measured .6uh which with 2 rollers ends up to be 1.2uH not including all the
external wiring in the tuner for the relays etc.

The performance of the AT4K tuner is designed mainly for low band operation
and Palstar advises that expecting 10 meter wide range Z matching is too
much to ask! The real solution is in a change to the antenna.

I use two antennas: 2 x 18 meters inverted Vee and 2 x 8 meters sloping
dipole. I am planning to change the 2 x 8 meters sloping dipole into a 2 x 5
meters sloping dipole, in order to get a better tuning on the 17 till 10
meterband.

That's what I can tell you for now. Perhaps there are more (better, improved
or additional) modifications, which I am not familiar with.

I enjoy the combination Mark-V, 91b, AT4k very much. It keeps me going on in
customizing it...


73, Hans Remeeus.
Ham Radio: PA1HR
www.remeeus.nl

Communication is about people, the rest is technology.


----- Original Message -----
From: "Harry Yingst" <ab2pn@yahoo.com>
To: <1000mp@mailman.qth.net>
Cc: <hans@remeeus.nl>
Sent: Saturday, January 31, 2004 5:29 PM
Subject: Re: [1000mp] Key Clicks Solution?


> I just got that same tuner (Palstar AT4K)
>
> What did you Mod on it???
>