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Title: AR88 RCA MOD Post by: KB5MD on September 25, 2018, 07:22:58 PM A simple mod for the AR88 RCA receiver that will greatly improve BFO use for SSB reception is to remove the twisted wire gimmick on the bfo
and replace it with a 100pf cap. Just thought I would pass this along for anyone using the great old boat anchor. Title: Re: AR88 RCA MOD Post by: Joe Connor on September 25, 2018, 10:13:53 PM There's a good discussion of this issue in Henry Rogers' article on the AR-88 on the Radio Boulevard site. Just scroll down to Insufficient BFO Injection.
https://www.radioblvd.com/ar88.htm (https://www.radioblvd.com/ar88.htm) Title: Re: AR88 RCA MOD Post by: WD5JKO on September 26, 2018, 02:00:05 PM As a former AR88 owner I looked into this issue as well. One consequence of increasing the BFO injection is that the BFO oscillator will "pull" in the presence of a strong AM signal. This can be both good and bad. The good part is that on a strong AM signal with QSB, the BFO may "Lock" to the IF frequency of the desired signal carrier. I think this is a form of "exalted carrier" reception. Other situations such as on SSB, the VFO may pull at the syllabic rate of the TX operator. This can sound pretty weird. A higher injection can be good. Perhaps a BFO buffer stage could be used to minimize "pulling"? Jim Wd5JKO |