I am a newbie to vintage Radio Restoration and I'am at the point
were I need to purchase an RF Signal Generator..
Some say to get one that goes below 100KHZ like the Simpson 75KHZ
the RCA 85 KHZ or the HEATHKIT 100KHZ.. I saw one on E'bay Today that started
at 160 KHZ.. DOES IT MATTER???
I would appreciate your advice... Thank You...FRED...N3JFN

If you're not going to work on Communications receivers, a generator that goes below 455KHz is really all you need. If you are going to do old car radios, a generator that goes down to 250KHz will be needed, and, if you intend to work on communications receivers, a generator that goes down to 50 KHz is going to be needed on occasion.

There are a couple of B&K and Eico generators that some folks like, which would probably work for AM broadcast, and old car radios, but If you are hoping to get into Communications receivers, an older "lab" grade generator with a good attenuator is really needed.

There have been tons of threads on this subject, with a good number within the last year here, so I'd recommend you do a search on the subject. You'll find a lot of information, recommendations, price ranges and places to buy, and you'll probably have to take notes as you go.

URM-25D goes down to 10 kHz, and has an output to drive a frequency
counter. HP 606A generators are no slouches either. Pretty sure they
reach 50 kHz. Both are vacuum tubed based.

Thank You Guys will watch this thread for further advice and also do some research on the subject in past threads... Keep up the Great Work... FRED... N3JFN... 73

You're right Pete, the 606A does, but there's no counter output, maybe on the "B".

One other thing to be aware of is that many of the superheterodynes out of the 1920s had really low IF frequencies, in many cases 60 kHz or lower. With better tubes and components, it was advantageous to raise the IF frequencies of receivers, and by about 1930, most manufacturers were using IF frequencies around 175 kHz. So the question of how low your signal generator should tune really depends on the kinds of radios you want to work on.

If you really need a low frequency signal generator, the General Radio 1001A gets down to 5 kHz.

Hi Mike,

I was referring to the URM25D when I mentioned the counter output.
That is a nice feature.

Pete

That HP6060A is a boat anchor ... are you willing to sacrifice benchtop real estate for something that large that has side handles like those used on stage speaker cabinets?!?! And vacuum tubes to boot!

I use a pair of 606A's for the boatanchor gear and they are better than the HP- 8640B and its built in problems. If youre going to be working with a range of single and double/triple conversion communications receivers you need to cover down to 50 kc and you dont want any Heath, RCA, Eico, or similar junk.

Its simple to convert that useless calibrator BNC to a counter out jack. Use the crystal in an old radio as a calibrator.

Carl

What kind of forklift do you use?

RRM

I keep mine on shelves. What do you use a forklift for

The 8640Bs aren't exactly portable either. Somethings ain't meant
to be moved.

...and your choice/recommendation would be...?

While I dont walk around with one swinging from each hand any longer they certainly arent very heavy and Im pushing 72. The last one I picked up a couple of years ago at Nearfest for $40 was a long walk back to the car. I think the URM-25D is as heavy or more and I lugged one of those around big long USN ships and up and down ladders (stairs for landlubbers) for years and with a TV-7D in the other hand. Makes a man out of you

Carl

Like Mike asked... what would you recommend that offers the same quality in that price
range?

Pete

Well, let's see now.... in fairness towards the previously referred to boat anchors, may I suggest the following worthy, analog alternatives that often sell for $200 or less:

My little pea brain immediately thinks of a Marconi TF-2016A which spanks both the HP and URMD25, considering it weighs less/smaller, solid state circuitry, AM/FM, 10khz-120mhz, has counter output, good stability.

My next thought leads me to two other spankers: Logimetrics 921A/925 & SG-1144U solid state units (has a nixie display for the tube junkies to get their "fix"), 10khz-80mhz, freq. lock, stable to 100hz, separate meters for AM-mod. & RF atten.

Two other relatively decent units to consider are the:
Phillips PM5324 (hybrid) 100khz-11.1mhz, CW/AM/FM & sweeps
Phillips PM5326 solid state, digital display, 100khz-125mhz, AM/FM

... and there you have it! Did I pass the test?

It's a 1/4" phone jack, not a BNC. It could be replaced with the one-hole style of panel-mount BNC jack. The 606A's calibrator is not convenient, as it's high-impedance and suitable only for crystal earphones. They fixed that in the 606B, but it gained a counter output too, so no point hacking the calibrator. (Really the aux out is for the 8708A Synchronizer but those aren't exactly common.)

Your picture made me laugh, Mars.

Dave Wise

The Marconi's are fairly rare, and you could get mitey gray waiting for one to show up. An interesting design, but fairly leaky, and constantly drifts, although the rate does slow down after an hour or so. That aside, it is an AM/FM, and composite signal generator, with very good frequency coverage.


This VHF version is just about useless with out the separate frequency lock box.


This generator should get an award for one of the worst generators ever. It does have frequency lock, but if you find one its usually WAY over priced for what it is.


I've had all three, bought them as not running/parts units, repaired, verified performance per the manuals, and got rid of them, especially the Dogimetrics, as soon as as possible.

I can't comment on the Phillips generators, having never owned them, but the 5324 has a frequency range similar to the 2016.

Many of the early non-synthesized solid state SG's had as long if not longer cold start warmup times than tube generators. I think even the solid state HP 8640B calls for 2 hours from turn on to reach its stabilty spec. I wasn't aware those Logimetrics jobs were that bad, it seems like the miltary especially the USAF loved the things. There are quite a few guys who fix them up and re-sell them- for prices more than they are likely worth but what exactly made them so bad?

Going to a synthesized signal generator was one of the best investments I made for my shop. Punch in the figures and go, fast heat crystal oven is at max stability in 5 minutes. No drifting, no fiddle farting with knobs, no guessing at what its doing. And thus far, its been totally reliable. Others might shun synthesized generators for complexity, but from what I have seen here at ARF many times, fixing a 606 A/B or some of the other more comprehensive tube SG's isn't always a stroll through the park either.

-Mark-

The absolute worst synthesized generators I ever owned were three Wavetek 3000 series.
Unbelievably HORRID phase noise and they needed a lot of TLC to keep running. The happiest
day of my life is when I dumped them.

The advantage of the HP-8640B, and to some extend the Boonton 102F, is they have a very
clean output which is needed to measure receiver dynamic range, blocking and MDS performance.
Most of fancier sythesized generators fall way short of the HP-8640B specs. I use my two
8640Bs and the Boonton 102F when I need that level of performance.

Of course all of this is nothing that would interest folks doing AA5s or early consumer radios,
but something who is involved in evaluating or homebrewing communications equipment they
are still the gold standard for anything that is affordable under $1000.00. I'd go with a
HP-606 if my choice was that or having to live with phase noise problems. Everyone's needs
are different.

Pete