Using a Rockland (Wavetek) 5100 Systhesizer as a VFO for A Viking II

[AJ1G]

A nice Vking Ii followed me home from NEARFEST yesterday afternoon.  I acquired it in trade from a friend.  It's a working unit, and a matching 122 VFO will follow eventually.  For the time being, I am going to put it on the bench for checkout using crystals and perhaps a Hallicrafters VFO that is part of my HT-40/SX140  setup.  I also have a pre-Wavetek Rockland 5100 synthesizer that works up to 2 MHz, and was thinking of using that as a VFO.  It puts out up to 10 V peak to peak into 50 ohms, the output can be attenuated using a set of attenuator switches.

Wondering what sort of RF voltage level the VFO input of the Johnson is looking for.  IIRC, the 122, like the Heath VF-1, has a 160 meter fundamental mode and a 7 MHz fundamental mode, so the 5100 synthesizer should work to drive the Viker on 80/75 and 40.  Anyone else ever used something like the Rackland 5100 as a VFO? If the Viking needs something more than 10 V P-P. am thinking of using a National
MB-40 tuneable interstage matching network I have as a step up transformer.

Sidebar - back around 1972, Rockland was operating out of a location less than a mile up the road from our house in West Nyack, NY.  I took an interview with them for a technician opening they had advertised when I was trying to line up a summer job while home from college but they were looking to fill the opening with a full time employee.  I picked up the 5100 at last fall's NEARFEST mainly as a nostalgia thing, I've used lots of Wavetek stuff over the years, but the 5100 was the first Rockland product I have come across in a long time.  I doubt I'll ever need to generate an AC signal down to a few milliHertz, but the 5100 apparently can do it.  I did set it to some very low frequencies, and watched the waveform slowly scroll across the screen of my Tek 535A.

[w3jn]

I use a HP3325A synthesizer as a VFO for my GPT-750 and HT-20.  Works perfectly, and you should be able to get by with a volt or two driving it.  At least that's what my HT-20 takes.

You shouldn't have to worry too much about phase noise using the Viker, but it is something I need to be aware of with the GPT-750.  The 3325 isn't great, phase noise wise, but looking at the output spectrum it's not terribly worse than using a HP8640B as the VFO.  What you do NOT want to do is use one of those function generators that use a variable resistor as the frequency determining element.  THAT will piss off everyone within 100KC of you!

[WD8BIL]

Put the multi-meter switch in the OSC position.
Without generator drive turn the mode switch to CW
Set frequency to whatever..... 1885...
Band switch on 160
Note the OSC current with no generator drive
crank the generator output up until the osc current reduces to half

This should give you enough drive to operate.
 

[AJ1G]

Thanks guys...looking forward to getting it on the air. 

I ran one back in 1978 to about 1980 when I first got back on the air as AJ2O and then AJ1G after my WB2ZPS general expired around 1973 when I was in college.  That one lost its low voltage B plus transformer that put a HUGE pall of tar smoke into my basement shack here, it's been a shelf queen ever since.  I did acquire some replacement iron for it last year, a nice LV B plus transformer and a mod transformer (the orignal one lost 1/2 of its primary at some point before I ever put it on the air).

[w4bfs]

.... it's been a shelf queen ever since.  I did acquire some replacement iron for it last year, a nice LV B plus transformer and a mod transformer (the orignal one lost 1/2 of its primary at some point before I ever put it on the air).

Clark, one of my V II would not make full mod audio and when I ohmed it out 1/2 of the primary was about 100 Ohms dcr and the other 1/2 was 1kOhm .... I opened it up and saw that the wire size for the good and bad sides were much different (iirc 28 ga for one and 34 ga for the other)  I'll bet the winders at EFJ (or contractors) ran out of the proper size and used what they could find to make production