Both books are in pretty good condition, especially the Filter book considering that it was published in 1975. The Antenna Theory textbook still has the 3.5″ disk in the back unopened.
I was hoping to get at least one of the Vibroplex bugs that were also in the auction, but a flurry of last minute bidding drove the price higher than I wanted to pay for them. Oh well.
Happy with the books I managed to get though. They’ll be good additions to the library.
There hasn’t been a whole lot of radio activity going on here lately since Field Day.
There were four state QSO parties going on this weekend (AZ, NV, PA, SD). After getting a SD station (W0SD), I decided to try to get at least one contact in the other three. I wasn’t able to find any more SD stations, but I did manage three contacts in AZ, three in NV, and eight in PA.
While tuning around the other bands (there wasn’t a whole lot), I scored contacts with hams in the Dominican Republic and Slovenia. There was also someone in Spain, but he had a bit of a pileup going that I wasn’t able to get through.
Replacing the DC blocking disc capacitor (C20, 0.01 μF) just before the Fine Atten pot helped clean up the output signal quite a bit. I didn’t get a picture of the wave form before, but it was pretty ugly looking and not very stable.
IG-102 wave form, about 500 kHz
Much better looking now, and much more stable.
Heathkit IG-102 schematic from https://www.vintage-radio.info/
Fortunately, my IG-102 came with the assembly manual. The IG-102 is roomy enough inside that it’s pretty easy to get in and probe around checking things.
Things I’ve found so far:
Audio frequency (AF) output, which the manual says should be 400 Hz, is around 260 Hz. With the AF dial turned all the way up, the AF waveform measures about 20Vpp.
I can reliably get RF output when the Coarse Atten switch is at the Hi position and the Fine Atten dial is all the way clockwise.
Setting the Coarse Atten switch from Hi to the middle position drops the frequency by about a factor of 10 (according to my M3 frequency counter).
Setting the Coarse Atten switch to the Lo position makes the RF output drop out.
Turning the Fine Atten dial counter-clockwise ends up changing the frequency (unexpected) instead of changing the signal level.
The band select dial is kind of fiddly. Sometimes when I switch to a different band, RF output drops out. Switching back and forth will usually bring the RF output back.
Band A (100 – 300 kHz) is the most accurate.
Bands B (310 – 1100 kHz) and C (1 MHz – 3.2 MHz) are about 50 kHz low.
Band D (3.1 – 11 MHz) is low by 0.5 – 0.7 MHz.
Band E doesn’t work.
Band F (32 – 110 MHz) is reasonably accurate up to 50 MHz, but maxes out around 75 MHz.
V1 12AT7 pin voltages
Pin
Spec
Measured
1
65
62
2
-4
-5
3
0
0
4
6.3 VAC
7 VAC
5
6.3 VAC
7VAC
6
62
59.6
7
-0.75
-0.38
8
0
0
9
0
0
V2 6AN8 pin voltages
Pin
Spec
Measured
1
70
62.8
2
-0.2
-0.5
3
1.5
1.57
4
6.3 VAC
7 VAC
5
0
0
6
125
127
7
130
130.9
8
0
0
9
2.5
2.64
IG-102 AF signal around 260 Hz
The RF signal sampled at pin 2 of the 12AT7 tube looks decent enough.
IG-102 RF signal around 370-ish kHz
Need to do some more poking around with the oscilloscope to check the RF waveform at other places along the output path to see what’s happening before I try to figure out what bits I might need to replace.
