Suggestions for high frequency signal generators

[bayjelly]

What are suggestions for "affordable" high frequency signal generators? With "high frequency" I don't really mean the HF band, but around 500 MHz at least, but preferably up to 1 GHz or much more. 5-6 GHz would be fantastic, but I realize that may be entering difficult territory.

I'm a hobbyist and don't have lab grade requirements for e.g. phase noise, but the generators I can find on eBay are often easily multiple times the price of even my Spectrum Analyzer and VNA.

I sometimes see that there are some cheap boards on eBay or AliExpress, any experience or recommendations regarding those?

[tautech]

Well you already have a SG in your SA TG if you use it in zero span mode. 

[bayjelly]

Right, tautech. I know that and even used that, but then my SA, which I really want to use in those sort of endeavors, is stuck in zero span mode at that particular frequency. Not super good if you want to use that signal as, say, the LO input to a mixer!

[tautech]

What are suggestions for "affordable" high frequency signal generators? With "high frequency" I don't really mean the HF band, but around 500 MHz at least, but preferably up to 1 GHz or much more. 5-6 GHz would be fantastic, but I realize that may be entering difficult territory.

Difficult indeed with such a wide spec and zero indication of budget. Please define affordable.

$2.5K will get you a 2.1 GHz modern proper RF gen but if you need more AWG like capability/features start at $1.5k and go up ! 
Some models to investigate:
SDG6000X
SDG7000A
SSG3000X
SSG5000X

[Zenith]

Try the used instrument market, HP/Agilent, Marconi, Philips and a load of others.

Look on ebay, but also check used test equipment dealers. Phone a few.  They usually offer some short guarantee, and sometimes have reasonable prices.

[S57UUU]

Look for an HP8648, these are nice, I have one. Can be quite cheap on Ebay. There are three versions, up to 1, 2 or 3 GHz.

A slightly older synth is the HP8656, up to 900MHz, and if you need a real boat anchor, HP8640.

Marko Cebokli

[mag_therm]

Check the attenuator of used sig gens.
When I bought my vintage Wavetek 3000 from the dealer, he told me the attenuator has 2 bad positions, so he added an external Narda to partially compensate. Any-way the price was right and I have years of use after re-labeling the selector positions.

I have since read that sig gens used to check transceivers can (commonly) be damaged if accidentally keyed with generator still attached.
The atten module in this unit is not repairable being leadless resistors partially embedded in solder bath,

[bicycleguy]

What about this?
https://rf-consultant.com/products/tpi-1005-a-signal-generator/

[switchabl]

What about this?
https://rf-consultant.com/products/tpi-1005-a-signal-generator/

Well, I could find almost nothing in the way of performance specifications. So, hard to tell. But it _looks_ like it is essentially just an ADF4351 + an amplifier and controllable attenuator? I would guess the output will be closer to a square wave than a sine over much of the frequency range.

Which is fine for some applications... but if that is the case then I would take a look at the similarly priced ERASynth Micro. That one goes to 6.4 GHz and comes with full specifications.

[S57UUU]

Yes, attenuators can be quite a problem on old generators (spectrum analyzers...). Not just burnt ones, also stuck ones.

Especially with HP, the attenuators tend to get stuck by themselves (some rubber part turns into goo).
I have three HP generators (8663, 8673 and 8683) and a 8593E SA, with stuck attenuators. But I simply put a sticker on them saying "below -30 dBm, add 20", if the 20dB section is stuck, for example.

Another vintage HP problem can be front panel keys, like, you press "2" and get "2222". Got this with the older ones with clicky keys, but also the newer ones with rubber keys, like the 8648.

Anyway, I find these old boxes very useful, not that much a problem working around these quirks. They are mostly repairable, but I'm just too lazy, therfore the stickers.

Marko Cebokli

[nctnico]

An R&S SMIQ is also a nice option. Before that I owned an Agilent ESG series which might be a tad better compared to the SMIQ. Both can be bought relatively cheap.