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Old 7th Nov 2020, 1:01 pm   #1
QQVO6/40
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Default Wiltron 610B sweeper.

G'day everyone.

Today I was given for free a Wiltron 610B swept frequency generator with the 6104 100kc to 100Mcs insert. I brought it up gently and it seems to work ok. Have not hooked it up to any test gear yet so here’s hoping.
Can’t whinge about the price!
Anyone here used one or have thoughts on it?
I am looking to use it for sweeping IFs on quite a few radios I have. I am thinking that with a 100Mc bandwidth it is going to be a bit difficult to get it to sweep 50 or 100kc at a centre of 455kc.
One comment I have read on another forum from the USA was that the attenuator did not reduce the signal enough for work on receiver Ifs.
As long as it does not leak I have numerous RF attenuators that are capable of making it quiet enough.
Thoughts anyone??
Anybody have and willing to share the manual for this as I do not have any info for it??

Thanks in anticipation.
Cheers.

Robert. VK2ZWZ.
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Old 8th Nov 2020, 8:50 am   #2
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Default Re: Wiltron 610B sweeper.

I had a quick look for the manual and I can see its not available for free download. There is a copy of the 610C - which is related enough to the B version to share the same extender card - from here. It doesn't include the schematics - however that's not the immediate problem here.

You can get the 610B manual if you are willing to pay - I see at least one on Ebay.

I can recall using a Wiltron sweeper back in the 1980s - not sure which model - but I know it went to 20+GHz, and I only wanted to sweep a few MHz at the time. That wasn't a problem for that unit.

On the presumption that the 610C and B aren't very different (they both use the 6104 plug-in you have), then looking at that 610C manual, its clear that you can define both the centre frequency and the sweep width of up to 10% of the whole span - so in your case that's about 10MHz max. It can be adjusted down to zero apparently.

It appears that it is also possible to set a start frequency and a stop frequency.

All that suggests that the 610C would at least in principle do what you want. I have to say the manual is remarkably light on specs! What I was looking for was the amount of random FM on the unswept signal - no sign anywhere of a figure for that. If you want to sweep say over 445 to 465kHz, and the FM noise deviation is +-1kHz say, you are going to get very fuzzy plots (i.e. amplitude uncertainty) at the edges of an IF filter.

Given the 610C manual doesn't even appear to contain a complete block diagram of the innards, its hard to say how they are generating the sweep. Presumably its some microwave source mixing solution - and there are people on here much better qualified to comment on that than I am. If so, then random FM noise may well prove to be a problem.

Quickest answer may be to switch it on and try it!


Richard
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Old 8th Nov 2020, 12:56 pm   #3
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Default Re: Wiltron 610B sweeper.

G'day everyone.
Thanks to everybody that looked at my thread.
And a special hello to Richard. Thank you for the effort of doing the research and then posting a reply to my thread.
I have been lucky in that a gentleman on one American forum where I posted the same question has given me the same heads up that you have given. That the 610C is quite similar to the 610B all 3 of us are guessing. I have managed to find more info about the 610C and nothing online about the "B" model. Only a couple of auction adds for the "B" book. There is 2 manuals floating around for the "C", one of 55 pages and one of 75 pages. The larger seems to be a later copy of the "C" manual so I downloaded and printed it.
The 610B I have was last calibrated in 2004 and it seems to be working quite well except for a noisy pot. Something I can live with as it is not too bad.
I have put my CRO on the output and if I don't open up the gain too much the waveform is a good sinewave. I have had a close look at the waveform on my scope and it is quite clean and not fuzzy so I am guessing there is not too much phase noise. Switch on the internal modulation and it changes dramatically.
When I read the bit of the "C" book I saw that it uses a square wave as the 1kc AM audio modulation. Ugly thoughts about the weird waveform relieved.
For an hour or so this afternoon I had it tormenting my AM broadcast receiver on 960kc so I guess it will be suitable to do the IF tuning I need.
One thing I noticed with it is that I can set it up to do a sweep of between 0% and 5% variable of the first or F1 frequency. This is easy to do.
Among others I have 2 RCA AR-88LFs and an AR-88D that will need restoration.
I did restore an AR-88D some years ago and set up the IF manually. I did it but it is a long and laborious job. This new sweeper will make it so much easier.
Anyway I had better stop before I put everyone to sleep.

Thank you Richard and thank you to everyone else who at least read my post.

Cheers all.

Robert.
VK2ZWZ
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Old 8th Nov 2020, 1:32 pm   #4
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Default Re: Wiltron 610B sweeper.

Robert,

you're welcome. I did note while reading the 610C manual that both AM and FM modulation facilities are available. I'm unclear why you would want that on a sweeper? But I'm not a regular user of such instruments, so there must be some requirement for it.

I can't see it as useful when sweeping across a narrow IF filter system. I would have thought you would want the cleanest possible sine wave (with no sidebands) that you can get!

Richard
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Old 8th Nov 2020, 2:53 pm   #5
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Default Re: Wiltron 610B sweeper.

Wiltron got taken over by Anritsu, and is still active in the US. Wiltron's number one product line were network analysers, so it's likely your unit was the signal source of one in the days before they all got stuffed in a single box, hence the large output signal only... but the screening ought to be reasonable.

An ex colleague became Wiltron's customer support manager, but I think this is before John's time, and he'll have been retired a long time by now. It was 1991 when I visited him in Sunnyvale Ca.

David
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Old 8th Nov 2020, 4:31 pm   #6
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Default Re: Wiltron 610B sweeper.

Wiltron 610 Sweeper.
I have the 610C model, with supporting plug ins and the manuals, not scanned.
I attach a scan of the specification, and some circuits, which appear to be for both the 610C and your 610B. I cannot help with your vhf plug in (signal source), as my plug in's cover different ranges. Noted on the full list of PI attached.
If you want me to scan the whole main frame manual and any of the PIs let me know.
My unit has been under the bench for some years waiting for me to check it out.
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Attached Files
File Type: pdf Wiltron 610C-B extracts wm.pdf (1.56 MB, 72 views)
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Old 8th Nov 2020, 10:29 pm   #7
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Default Re: Wiltron 610B sweeper.

I've not used one of these but my guess is that it will be best suited for sweeping through a front end RF preselector where the filter bandwidth might be 200kHz or more. This is because it will be prone to some jitter and drift on narrower spans. It probably uses a downconverter to convert a V/UHF VCO down to 0-100MHz and this won't be that stable. However, I'd expect the designer to have tried quite hard to give the VCO fairly good short term stability but it will probably drift quite a few kHz as the whole chassis warms up and it may also have residual FM on it as Richards suggests.

I'd expect the RF levelling to be very good so this is one area that this unit should shine. It could probably be used to measure filters for insertion loss and ripple with fairly low uncertainty. You would just need to use a decent RF detector after the filter. Something based on the AD8307 logamp would work quite well here I think. Adding an attenuator at the RF output would help minimise mismatch uncertainty for more critical work.
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Old 8th Nov 2020, 11:59 pm   #8
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Default Re: Wiltron 610B sweeper.

The GHz plugins look to be YIG oscillators with a Gunn diode negative resistance generator, but the 100k-100MHz ones are labelled voltage tuned oscillator.

Unless the plug-ins have range switches, then that ratio is going to mean a free-running VCO mixed with a fixed oscillator (hopefully crystal controlled) in the plug in.

The whole thing looks to be free running.

Jeremy's right. OK for sweeping RF circuits but it's going to run into limitations if you try to plot IF bandwidths of radios. OK for tellies.

The comparable HP 8601A 110MHz sweeper has no plug ins, but it does have a frequency discriminator loop to stabilise and linearise the VCO

David
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Old 11th Nov 2020, 12:35 am   #9
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Default Re: Wiltron 610B sweeper.

G'day everyone.

Sorry for my delay in replying.
Last 2 days I have had to travel some distance to see my surgeon and anesthetist as I am having major abdominal surgery in under 2 weeks. Not looking forward to it as my doc says I will be out of action for around 8 weeks.

Thanks again for your input Richard. Much appreciated.
Thanks David for the history of Wiltron. It helps to know that Anritsu is involved as it has shown up on various search sites and I was not fully aware that there had been a company change.

Bill, you are a gem!! Thank you for your help and knowledge it is so very much appreciated. The information about these bits of kit is quite rare on the net. I would love to graciously accept your very kind offer of a copy of the book. There will not be any rush for this as it will be a while before I need to use the 610B. As stated earlier I will be out of action for a while.
The first job it will be used for is to do the IFs in the AR-88LF which is on the end of the bench now. Fortunately I have a turntable setup to position heavy radios so I won't have to lift it (after abdominal surgery?? NAH!! Not going to happen!)
The book is going to be good as I had a bit of a play with the sweeper last night and even though the output looks good on my CRO with no jitter. When I hooked it up to my counter it would not go below 560kc and wandered around a lot and the highest it would go was around 48Mc. Not good as it's nominal range is 100kc to 100Mc.
So Jeremy and David I guess you will both be correct in saying that it will not be all that suitable for setting up IFs in my radios.
The sweeper obviously needs some work! When I can I will start out by going over the power supply and doing caps and really checking out the regulation to make sure it is rock solid. As you have both said it is a VCO with no bandswitch for this HF module so PWR Supply stability is vital. I have a good Fluke differential voltmeter and CRO to check stability plus other gear so all good there.

Overall I can't complain as it only cost me a bit of fuel and time to go and get it. Couldn't be better!

I need to thank all of you for being so helpful with this.

Cheers.
Robert. VK2ZWZ.
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Old 11th Nov 2020, 2:13 am   #10
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Default Re: Wiltron 610B sweeper.

Why AM on a sweeper?

Old school measurement technique used 'crystal' (diode) detectors into AC amplified voltmeters to measure signal strength of an amplitude modulated signal. This avoided the need to make precise DC amplifiers for the detectors. In a way it was like having a chopper amplifier.

Why FM on a sweeper?

It can be demodulated from the signal being measured and from the phase of the demod signal, the relative group delay of the channel being swept can be displayed. A much more difficult process, so scores triple points!

David
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Old 11th Nov 2020, 9:04 am   #11
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Default Re: Wiltron 610B sweeper.

Just as an after thought on this thread, I've found its very easy to "sweep" a standard signal generator that has an FM option across the 10 - 20 kHz needed to say, get a curve for a 455kHz IF.

The signal producing the sweep will typically be an external oscillator - sine wave seems to be fine. That signal is fed to the external FM input of the generator, and also the X-input of a scope. A diode detector - maybe with a RF amp in front of it is fed to the Y-input of the scope.

Richard
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Old 28th Nov 2020, 1:14 pm   #12
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Default Re: Wiltron 610B sweeper.

G'day everyone.

Sorry for the delay in my reply to the thread.
Just got out of hospital after abdominal surgery so I am feeling quite under the weather.
So good to be home though.

Thanks for the suggestion Richard about using an RF sig gen that has an FM modulation capability. The only one I have like that has a lower frequency limit of 1.25Mcs.
David "Radio Wrangler" has made that suggestion in posts of the past so you are both on the same track there.
Not to worry. I will have a play with what I have got and see what I can come up with.
At the very least I can just peak the IF stages as I am using the receivers for communications operation so a passband of around 3.5kc is acceptable.
Or I can just broadband the IFs using the old manual method.
3rd thing I can do I guess is to just buy an el-cheapo sweep gen from the net that has a trigger output and play with that.
I would like to thank everyone that has contributed to this thread.
Please stay safe.
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