IMPROVEMENTS TO THE ORIGINAL RADIO:
1) LO PLL synthesizer (2 boards) replaced by 32bit DDS AD9851 (Direct Digital Synthesizer). Eliminates slew rate issues with 23 million frequency changes / second (.04uSec/freq). Allows frequency resolution below 1hz.
2) Stratum 3 oven controlled crystal osc. improves freq. stability and eliminates most of the DDS generated birdies.
3) LO amp after the DDS increases output level for the 10m band to an exceptable level for the mixer. Original design output was too low causing distortion.
3) Crystal controlled BFO SSB selection replaced by computer controlled 32bit DDS AD9850 IF generator.
4) Audio input selection replaced by self contained SSM2019 full spectrum audio preamp with automatic line level limiter. The preamp directly feeds the balanced modulator and does not allow overdriven audio input.
5) Reconfigured the IF boards 2.4khz crystal 8.830mhz IF filter with a front panel selectable 4.0khz or 2.4khz or 6.0khz 8.830mhz IF filter board. The board uses small signal latching relays controlled by the main CPU to select the TX/RX bandwidth and automatically adjust the IF frequency.
6) Replaced original 6502 CPU with 16bit HC9S12D64 Freescale CPU with Flash memory and EEPROM freq storage. The IF DDS also has its own 9S12D64 CPU.
7) Converted analog RIT control to Digital RIT control with front panel selectable ON/OFF control.
8) Converted analog IF shift control to digital IF shift control with automatic IF shift depending on crystal filter selected.
9) Converted digital main tuning knob from 1000hz or 50hz step frequency selection to 1000hz or 5hz step frequency selection.
10) Performed all MODS from issues of QST (see link below for listing)
Right click (below) to download each PDF
Heathkit Matching Accessories
HWA-5400-1 Matching Power supply / Speaker / Clock
25Amp Linear power supply
I have this, but dont use it anymore. Due the the Linear nature of this supply, its gets very very hot. I use a small 30A switchmode.
HM-2140A SWR Meter (with Peak Detector & Remote monitor)
HO-5404 Station Monitor (with Panadapter)
HD-1481 Remote Coax Switch
SA-2060A Manual Tuner
SB-1000 Linear Amplifier
HL-2200 Linear Amplifier
AMPLIFIER I am currently using
Dentron GLA-1000 80m thru 10m amplifier, modified to use a single Russian GI7B tube by KB9YSJ. A tuned input board was added by me. Output is 500W output (dead key) for 60watts input. 1000W PEP @ 60W (with 200ma Ig..... WOW)