[Lowfer] Can I expect to receive .... Schedule

[Douglas D. Williams]

Bill,

I sent you that Burhans article directly.

Since you seem to have several projects going in already, I remembered that
MFJ produces a receive only "tuner" that supposedly works from 150 kHz to
30 MHz. The model number is MFJ-956. I also remembered that I had one in a
drawer in my closet! Opening it up and comparing it to the four page
"owner's manual" and schematic, I note that it consists of:

(a) so239 input/output
(b) from the input the signal first goes through a rotary switch that
allows the user to select one of four values of inductance (1 uHy, 22 uHy,
330 uHy, and 2.5 mHy), or bypass the chokes. The signal then goes through a
365 pf variable capacitor.

That's all there is to it. I note that three of the chokes are of the small
type that resemble regular 1/2 watt resistors, and that it would be easy to
remove them and replace them with chokes of higher inductance, if one
wished to lower the frequency range of the unit. I imagine if one removed
the three smallest value chokes, and replaced them with higher value chokes
the range of the unit could probably be made to be useful from 10 kHz to
500 kHz or higher.

The construction quality is typical MFJ, but there really isn't much to go
wrong with the unit, unless the rotary switch just wears out.


73, Doug KB4OER



On Sat, Feb 2, 2013 at 9:21 AM, WD8ARZ <wd8arz at comcast.net> wrote:

> It is very readable Doug, thank you.
>
> Once I finish a modification on a Geiger counter, finding a mike and
> connector for my T4XC, and redo my capacity hat for my HiQ 5-160 mobile
> antenna, this tuner project will be next on my to do list .... hi hi
>
> Have a TS-480HX in the mobile, and a FT-1000MP on the base feeding that
> windom antenna. Some times am on 7218 or 7225 of late, but available for a
> schedule if you like. Am retired a few months, so can be flexible ... hi hi
>
>  73 from Bill - WD8ARZ
> South Bend, Indiana a mile south of the Michigan border
> You know, the lake effect snow area ... hi
>
> On 2/2/2013 8:28 AM, Douglas D. Williams wrote:
>
>> As I recall, I made mine with a bunch of chokes I purchased from Mouser,
>> and a rotary switch to select between them. For the "C" I used an air
>> variable cap as well as a switch that inserted even more "C" from fixed
>> capacitors as needed. You could definitely hear a big increase in band
>> noise when you adjusted the settings properly for impedence matching. The
>> bandwidth of the match was narrow and the lower I went in frequency the
>> more narrow the match became. Of course, it was strictly for receive.
>> I'll see if I can scan that old article. Im afraid the quality is bad.
>> Hopefully, it will be readable.
>> 73, Doug KB4OER
>>
>>
>