## Configuration

- Firmware: 1.01.004 (upgraded 23 May 2026)
- Callsign: KF8EEZ
- Band: 20m
- Channel: 370
  - 8 minutes after, 14,097,180 MHz
- Autostart: TRACKER2
- QRP-labs S/N: 969

### Background info

- QRP-labs u4b info page: <https://qrp-labs.com/u4b>
- Traquito channel reservation: <https://traquito.github.io/channelmap/>

## README

Edited `README` on u4b to contain contact and WSPRtv tracking information in the unlikely event that someone can find it.

:::{.callout-note}
IF YOU ARE READING THIS:

BALLOON OPERATED UNDER CALLSIGN KF8EEZ.
LAUNCHED FROM DAYTON, OHIO, USA.

TRACKING:
HTTPS://WSPRTV.COM/?CS=KF8EEZ&CH=370&BAND=20M

EMAIL:
PHONE:
:::

## GPS antenna

half wavelength: 95.14683639918243 millimeters
quarter wavelength: 47.57341819959122 millimeters
quarter wavelength * 95%: 45.194747289611655 mm
feed length: 25.400000000000002 mm
total length: 70.59474728961166 mm


## HF antenna

top and bottom arms from U4B about 5 inches. Antenna arms should be about 198.84837766362426 inches. I created two spools of 200 inch long each. For both, need to cut about 6.16 inches off of the spooled wire.

### Upper

```{python}
print(200 + 5 - 198.84) 
```
= 6.16 in

### Lower

```{python}
print(200 + 5 - 198.84) 
```
= 6.16 in



## GPS antenna

Twisted pair feed, 50mm arms. Tested. Good GPS fixes.

## Programs

### Variables

- C is the count of transmissions since wake up
- N is the number of transmissions before switching to high-power (0-based)
- T is a flag for test mode
  - T=1 - test mode
  - T=0 - live mode - must be in live mode for flight
- B is the number of times to blink the led, set to 5
- X is the ERLON - Easting value
- Y is the ERLON - Northing value
- Z is the "big number" for telemetry

### TRACKER2

This is the primary program. The MYTELE and MYGPS subroutines enable control of a test mode which doesn't need GPS or ability to transmit.

```
PRINT "START TRACKER2"
RUN "INIT"
RUN "SHOW"
LET B = 5
RUN "BLINK"
PRINT "INITIAL GPS"
RUN "MYGPS"
LET B = 2
RUN "BLINK"
10 PRINT "LOOP AT #VC"
RUN "SHOW"
RUN "MYTELE"
LET C = C + 1
IF C > N
    LET HP = 1
ENDIF
RUN "MYGPS"
GOTO 10
```

### INIT

Initialization should run once on power up.

This code should be edited for each flight. 
Specifically, set:
- channel number: `CH=xxx`
- test mode: `T=1` for test without GPS/Telemetry OR `T=0` for live

```
PRINT "INIT START"
LET CH = 370
LET HP = 0
LET C = 0
LET N = 2
LET T = 1
LET B = 5
PRINT "HOST USB:    #US"
PRINT "HIGH POWER:  #HP"
PRINT "FREQUENCY:   #FQ"
PRINT "CHANNEL:     #CH"
PRINT "CALLSIGN:    #CS"
PRINT "TEMPERATURE: #TK"
IF T = 1
PRINT "*** TEST MODE ***"
PRINT "FAKE GPS/TELE MODE"
ELSE
PRINT "REAL GPS/TELE MODE"
ENDIF
PRINT "INIT DONE"
```

### SHOW

Prints out the current state

```
PRINT "SHOW START"
PRINT "LLH:  #LT #LN #AT"
PRINT "GPS:  VALID: #GV LOCK: #GL SPEED: #GS CALIB: #CL"
PRINT "GPS:  NSAT:  #SC"
PRINT "CNT:  #VC"
PRINT "TEMP: #TK"
PRINT "POWR: #HP"
PRINT "SHOW DONE"
```

### MYGPS

This is my GPS program, it lets you use the GPS in a test mode without an actual signal. Don't acquire GPS if in test mode (T=1)

```
PRINT "GPS START"
RUN "LEDOFF"
IF T = 0
PRINT "REAL GPS"
GPS 360
ELSE
PRINT "FAKE GPS"
DELAY 2000
ENDIF
RUN "LEDON"
PRINT "GPS END"
```

### MYTELE

Don't transmit if in test mode (T=1)
This packs additional telemetry into the Z variable and sends a 3rd telemetry packet.

THESE URLs create the telemetry packet decode for WSPRtv.com:
https://wsprtv.com/?cs=KF8EEZ&ch=216&band=20m&start_date=2026-05-17&ct_dec=ct,s:2_500:0:1,2:0:1,38:0:1,1000:t100,1000:t101&ct_labels=count,power,nsat&ct_llabels=spot+xmit+since+power,power,number+sats

https://wsprtv.com/tools/ct_wizard.html?spec=https%3A%2F%2Fwsprtv.com%3Fcs%3DKF8EEZ%26ch%3D216%26band%3D20m%26start_date%3D2026-05-17%26ct_dec%3Dct%2Cs%3A2_500%3A0%3A1%2C2%3A0%3A1%2C38%3A0%3A1%2C1000%3At100%2C1000%3At101%26ct_labels%3Dcount%2Cpower%2Cnsat%26ct_llabels%3Dspot%2Bxmit%2Bsince%2Bpower%2Cpower%2Cnumber%2Bsats


```
PRINT "TELEMETRY START"
RUN "LEDOFF"
LET Y = ERLAT 1000
LET X = ERLON 1000
LET Z = 0
LET Z = PACK Z 1000 Y
LET Z = PACK Z 1000 X
LET Z = PACK Z 38 SC
LET Z = PACK Z 2 HP
LET Z = PACK Z 500 C
IF T = 0
PRINT "REAL TELE"
TELE
TELEC Z
ELSE
PRINT "FAKE TELE"
DELAY 2000
ENDIF
RUN "LEDON"
PRINT "TELEMETRY END"
```

### LEDOFF

Turn LED off

```
OUT 19 0
```

### LEDON

Turn LED on

```
OUT 19 1
```

### BLINK

turns led on and off B times. you must set b first

```
FOR L = 0 TO B
RUN "LEDON"
DELAY 100
RUN "LEDOFF"
DELAY 100
NEXT
```