VFOs for broadcast TX's. What are you using?

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VE7 Kilohertz:
Merry Christmas and happy new year to everyone!

Several us of are working on installing VFO's in our bcast rigs and moving away from rock bound operation and I am curious to know what you are using for a VFO and how you interfaced it with your particular rig and what modifications to the transmitter you made to get it working. I have several ideas about how to do it but would like to see what other creative minds are doing.

Look forward to hearing from all you broadcast TX VFO users.

Cheers

Paul
VE7KHz

W2INR:
I use a Globe 755a self contained unit. On the Collins 21E.  I don't recall how I injected the signal but I beleive it was right into the Cyrstal injection point.

Sweet and simple

Works well

W3NP:
I started out using a Johnson 122 VFO with my Gates BC-1G. I injected it into one of the xtal ports - I think I made a slight change to the oscillator unit in the TX - pulled a cap out and changed the value of another - got it in my notes somewhere.

Now I am using an old Fluke digital signal generator. It will allow me to use a long piece of RG-62 and place the VFO near the operatiing position.

N3WWL:
I use a Kenwood 870 as my exciter/VFO/receiver for the Raytheon RA250. The 813 driver was reconfigured grounded grid/broadband input.  The 870 has an automatic antenna tuner, so input tuning is simple.  It takes 35 watts drive to achieve proper parameters.

w3jn:
AN outstanding synthesized VFO can be had for almost nothing in the form of an old HP synthesized signal source.  These beauties go from 1 millihertz up to 13 MHz and have a tracking 13-23 MHz output and have adjustable attenuators that go from -88 to +13 dBm.  I've seen them for as little as $10 (I paid $20 for mine).  The downside is they're a bit big, and you have to JS up a matching network for their 50 ohm output.  They have OUTSTANDING phase noise properties, and you can use them as a low-distortion audio source or as a regular sig gen for aligning receivers, etc.  Their long term stability is 10-9, and short term (after warm up) is comparable.  Much better in all respects than a typical ricebox.  I gave mine to the HUZman who is going to use it with his BC xmitter.

Another beauty is the HP 3330 - like above, but freq input/attenuator setting is via keyboard, and sweeps as well! (either freq or amplitude).  I scored one of these at Timonium for $15 - works perfectly but the front panel paint is all flaked off.  This mates with the 3571A spectrum analyzer (available on eBay for <$100, which is where i got mine) or the 3572A network analyzer.  All OUTSTANDING instruments (if a bit limited in freq range).

73 John

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