Heathkit SG-8 Signal Generator

[Notimetolooz]

It is great that HP equipment is more affordable now. I have some myself and I don't usually spend a whole lot on things. That being said, you have to keep in mind that a piece of HP test equipment built in the 1950's will require re-capping just as a radio or TV from that era. HP used very high quality parts so they hold up better than others, but there are limits on how well anything lasts. Solid state test equipment made more recently are less likely to need restoration before they can be used. Repair shops in the 40's through the 70's seldom had HP equipment.
There are brands that fall between HP and say Heathkit in precision. Heathkit items are very easy to work on since they were intended for assembly from scratch. There are service grade brands with better performance that are factory built but are simpler than HP. B&K, RCA, EICO, Sencor, Leader and Tektronix, etc.
Here is my modified SG-8. My B&K 2005A RF generator and HP 5382A frequency counter. Also my Leader LAG-27 audio generator, a home-built 455KHz generator and my RF coupling loop. I think I found the SG-8 locally on Craig's list. The others were very carefully selected form ebay. The B&K RF generator had some broken front panel pieces (poor packing) that I was able to glue back together. Except for the SG-8 the equipment shown is solid state, but I think I replaced the electrolytics in all of them.

[vortalexfan]

Originally Posted by Notimetolooz

It is great that HP equipment is more affordable now. I have some myself and I don't usually spend a whole lot on things. That being said, you have to keep in mind that a piece of HP test equipment built in the 1950's will require re-capping just as a radio or TV from that era. HP used very high quality parts so they hold up better than others, but there are limits on how well anything lasts. Solid state test equipment made more recently are less likely to need restoration before they can be used. Repair shops in the 40's through the 70's seldom had HP equipment.
There are brands that fall between HP and say Heathkit in precision. Heathkit items are very easy to work on since they were intended for assembly from scratch. There are service grade brands with better performance that are factory built but are simpler than HP. B&K, RCA, EICO, Sencor, Leader and Tektronix, etc.
Here is my modified SG-8. My B&K 2005A RF generator and HP 5382A frequency counter. Also my Leader LAG-27 audio generator, a home-built 455KHz generator and my RF coupling loop. I think I found the SG-8 locally on Craig's list. The others were very carefully selected form ebay. The B&K RF generator had some broken front panel pieces (poor packing) that I was able to glue back together. Except for the SG-8 the equipment shown is solid state, but I think I replaced the electrolytics in all of them.

OK, thanks for the info.
I'm just curious, how do you hook up a frequency counter to a signal generator if I got one?

[Notimetolooz]

Good question. That points out a bit of a problem normally. The output of a typical RF generator is very small. It only takes something like 10 uV ( 10 one millionth of a volt) of signal at the radio antenna for the radio to receive it. The problem is many frequency counters need something like at least 100 mV for them to work. One thing to do is turn the generator output up to max to read the frequency and then turn the output down before connecting to the radio. Another thing that sometimes works is to modify the generator and bring out the signal before it goes into the output attenuator to a separate connector. The B&K 2005A has this already done. It has the normal output connector that the amplitude can be varied and a frequency monitoring output connector. Some people have bought small frequency counter modules and install them in the generator if there is room. I don't think the modules have a very precise timebase oscillator in them however.

[Electronic M]

Originally Posted by Notimetolooz

Good question. That points out a bit of a problem normally. The output of a typical RF generator is very small. It only takes something like 10 uV ( 10 one millionth of a volt) of signal at the radio antenna for the radio to receive it. The problem is many frequency counters need something like at least 100 mV for them to work. One thing to do is turn the generator output up to max to read the frequency and then turn the output down before connecting to the radio. Another thing that sometimes works is to modify the generator and bring out the signal before it goes into the output attenuator to a separate connector. The B&K 2005A has this already done. It has the normal output connector that the amplitude can be varied and a frequency monitoring output connector. Some people have bought small frequency counter modules and install them in the generator if there is room. I don't think the modules have a very precise timebase oscillator in them however.

It the counter is microcontroller based and has a crystal osc it can be very precise.

[Notimetolooz]

Depends on how good the crystal oscillator is more than anything. You get what you pay for.

[vortalexfan]

Unfortunately I can't seem to find any frequency counters on ebay that are under $100 except for the cheap Chineseum kits, but they don't have a case and they require a 9V battery to operate and use a WiFi Antenna style input plug, and they don't seem to have any sort of adjustments on them like the factory built ones that are going for over $100 and as much as $25,000 for a Hewlett-Packard Agilent model from the 1970s...

[Notimetolooz]

Oh my. You need to sharpen your ebay skills.
Search on "frequency counter", select "pre-owned" and something like a max of $ 50. I saw at least half a dozen decent ones, even a HP or two. Out of those you have to look at the shipping costs and add that to find a total below $100. Some of the remaining have technical factors like a minimum of 20 MHz that disqualifies them. That might only bring it down to one or two or so. But if none look right you may have to try again in a couple of days.
You want to get one that covers the frequency range you will be working with, for broadcast AM maybe 10Hz to 2 MHz, Shortwave 10Hz to 25MHz, FM 10Hz to 120 MHz or TV 10Hz to 250 MHz. BNC input connector. You may have to do some research, you definitely want one with a crystal timebase oscillator, usually 10MHz. Hopefully you will have the time to run it past the forum for opinions.