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Title: Problem with Johnson Ranger VFO Post by: w4fms on April 09, 2019, 11:51:22 AM Hello:
My Ranger 1 VFO is giving me some problems and could use some help. On 160 and 40 meters (where the VFO is not multiplied), tuning the buffer cap (C7), can vary the vfo freq by a couple KC either way. Changing the drive level (R13) of V4 will vary the freq as well. All seems fine on 80m when the doubler is in operation...as I don't hear any frequency change at all. On these bands, the spot and the actual transit frequency differ by over 1Kc as well. Seems the 6CL6 (V4) is pulling the vfo off freq. Any ideas on a fix appreciated. Thanks Frank, W4FMS Title: Re: Problem with Johnson Ranger VFO Post by: WA1LGQ on April 09, 2019, 02:18:58 PM Did you check the OA2 regulator tube and the 10k resistor R3? Check voltages, maybe the coupling cap C22 is bad?
Larry Title: Re: Problem with Johnson Ranger VFO Post by: WA5VGO on April 09, 2019, 04:37:04 PM This is a well known problem. It’s caused by Johnson running the VFO on the operating frequency on these bands. Make sure all of the screws are in the VFO covers and they’re tight. Also, installing insulated shaft couplings on all of the shaft extensions often helps.
Title: Re: Problem with Johnson Ranger VFO Post by: KA0HCP on April 10, 2019, 01:13:18 AM https://www.w8ji.com/johnson_vfo_chirp_jump.htm
Checkout the tips from W8JI on rangers and valiants. Title: Re: Problem with Johnson Ranger VFO Post by: w4fms on April 10, 2019, 10:07:19 AM Thanks for the replies. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
It's not the OA2 or R3. I've incorporated the W8JI mods (removing the fiber washers) as well. In my case, I can vary vfo frequency in spot mode by adjusting the buffer control...so no high power necessary. This only happens though when the vfo freq is not multiplied. I'll keep on it. Frank, W4FMS |