[usa2003ardf] Transmitters

Gerald Boyd wb8wfk at worldnet.att.net
Thu Aug 7 17:58:58 CDT 2003


We have not had an over heating problem in N.M with our ammo case

However the problem we are having is that the ammo case based transmitters
are just to heavy.

We currently have a design effort in place to replace them with a new custom
design transmitter for ARDF use. I have received comments from several
people which are being fed into the paper design.

1. The transmitter will be a single PCB board that incorporates the
controller along with a VHF and HF transmitter.

2. It should be able to generate FM, AM and keyed carrier AM (VHF).

3. It should be able to generate 80M CW.

4. It MUST be able to recover and remember its state after a power
interruption (start on time and stay in sync).

5. It should have the option to operate on VHF and HF at the same time to
allow the hunting on either band during the same session.

6. It should use SMT parts of current vintage.

7. MUST be small in size, lightweight so all five units will fit in a

8. Must be able to operate as a MO homing TX .

I am currently investigating a DDS chip that will allow me to generate CW,
FM, AM, and Keyed carrier AM under software control (AT VHF). The
investigation will see if it is possible to use it in this application.

If you know of something you would like to see in the design please let me


----- Original Message -----
From: "Kenneth E. Harker" <kharker at cs.utexas.edu>
To: "Sam Smith" <sam.smith at ece.gatech.edu>
Cc: <usa2003ardf at kkn.net>
Sent: Thursday, August 07, 2003 6:47 AM
Subject: Re: [usa2003ardf] Transmitters

On Thu, Aug 07, 2003 at 08:05:48AM -0400, Sam Smith wrote:
> I have 5 ammo boxes made up with assorted old HTs for the 2 meter
> transmitters, the ON7YD 80 meter transmitter (you can get the board for
> this from FAR circuits) and piccon controllers. A 7ah gel cell, antenna
> connectors, a switch to select 2M or 80meter. A small circuit to turn on
> and off the oscillator on the 80M transmitter. The only things coming
> out of the box are the antenna connectors.

How do you charge the gel cells?  If I remember the ones in Georgia, there
were binding posts on the outside of the ammo cases that I assume go to the
gel cell battery terminals.  Are there charge controllers built into the
If so, what kind/where do you get them?  If not, what external charge
controller do you use?

Also, for those who use ammo cases, have you ever had overheating problems?
It can get really hot in Texas, and I wonder if anything goes wrong with
gear when it gets really hot...

Kenneth E. Harker      "Vox Clamantis in Deserto"      kharker at cs.utexas.edu
University of Texas at Austin                   Amateur Radio Callsign: WM5R
Department of the Computer Sciences          Central Texas DX & Contest Club
Taylor Hall TAY 2.124                         Maintainer of Linux on Laptops
Austin, TX 78712-1188 USA            http://www.cs.utexas.edu/users/kharker/
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