HP / Agilent / Keysight · Signal generator · c.1984–c.1998
HP listed the 8656B as new in its 1985 catalog, an economical programmable signal generator for receiver testing. It covers 100 kHz to 990 MHz in 10 Hz steps, which reaches the IF and local-oscillator frequencies of most receivers and the 800 MHz mobile band, and a new long-life output attenuator gave it ±1 dB level accuracy down to -127 dBm. AM and FM come from internal 400 Hz and 1 kHz tones or an external source, and HP patented the DC-coupled FM technique it used. Every key has a two-letter HP-IB code printed next to it, so programming it is easy, and HP's later 8648 generators kept those codes. It stayed in HP's catalog through 1998. Hunt for one with Option 001, the high-stability time base, if frequency accuracy matters to you.
Options and accessories
Check the listing photos and the rear panel against this list, and ask the seller about anything you can’t see. A missing option or probe should come off the price.
Resettable reverse-power protection guards the output against up to about 50 W from a keyed transmitter, so a generator with no output may only need that protection reset, or may have damage that got past it. The frequency, level and modulation readouts are LED displays, so check that every digit lights.
New to used bench gear? How to check used test equipment covers self-tests, fuses, the voltage selector and shipping, and what “calibrated” means in a listing.
Buying guide
We'd buy 7587scott's 8656B titled tested working at $336 delivered, just under the $340–775 band, though $136 of that is shipping on a 40 lb generator. There are at least 19 for sale, and the cheapest plain US unit is $250 with free shipping, while henno10000's at $489 is the one titled with Option 001, the high-stability time base worth hunting for if frequency accuracy matters. Ask for a photo set to a frequency with every digit of the LED displays lit, a 0 dBm reading at 100 MHz on a power meter, and how it'll be double-boxed. Skip nubicom2003's as-is units at $371 delivered from South Korea, which cost more than several titled working ones, and alltest's $1,997 ask at about 3.5 times the median.
$249.99delivered
The lowest delivered 8656B at $250 with free shipping. It isn't titled tested and the photo shows it switched off, so ask for a photo with it on and every display digit lit.
HP Hewlett Packard 8656B Signal Generator 0.1- 990 MHz - Free Shipping
$335.55est. delivered
Titled tested working at $336 delivered, just under the band. Ask for a 0 dBm reading at 100 MHz on a power meter, and how a 40 lb generator will be packed.
HP 8656B Signal Generator 0.1-990MHz Synthesized RF Generator Tested Working
Delivered prices include shipping as eBay quoted it to a US address on Oct 14, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Snapshot
Checked . Some may have sold.
Delivered prices include shipping as eBay quoted it to a US address on Oct 14, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Used$249.99delivered
$249.99 · free shipping
Buy It Now$249.99
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Good buy
Free shipping. Not titled tested, and the photo shows it switched off.
Seller: medmart
99.4% positive
Used$335.55est. delivered
$200.00 + $135.55 shipping
Buy It Now$200.00
This seller takes offers, and many sellers accept less than the asking price.
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Good buy
Titled tested working. Shipping is $136 of the total.
Seller: 7587scott
99.6% positive
For parts$371.00est. delivered
$171.00 + $200.00 shipping
Buy It Now$171.00
This seller takes offers, and many sellers accept less than the asking price.
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Our take
Titled as is, so treat it as broken. Costs more delivered than several titled working units.
Seller: nubicom2003
99% positive
Used$489.17est. delivered
$345.00 + $144.17 shipping
Buy It Now$345.00
This seller takes offers, and many sellers accept less than the asking price.
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Our take
Titled with Option 001, the high-stability time base.
Seller: henno10000
100% positive
Used$550.00est. delivered
$300.00 + $250.00 shipping
Buy It Now$300.00
This seller takes offers, and many sellers accept less than the asking price.
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Our take
Option 002 as titled, rear-panel RF output and inputs. Ships from Singapore; check the line setting.
Seller: chw415
100% positive
Used$612.83est. delivered
$549.00 + $63.83 shipping
Buy It Now$549.00
This seller takes offers, and many sellers accept less than the asking price.
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Our take
Photo shows it on with a cable connected. Not titled tested.
Seller: jfrederickjr513
100% positive
Used$613.86est. delivered
$499.99 + $113.87 shipping
Buy It Now$499.99
Our take
Photo shows it on with the displays lit. US dealer.
Seller: hollitronic2
99.9% positive
Used$2,177.73est. delivered
$1,997.00 + $180.73 shipping
Buy It Now$1,997.00
This seller takes offers, and many sellers accept less than the asking price.
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Priced high
About 3.5 times the median, with nothing extra titled.
Seller: alltest_instruments
99.5% positive
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