Hello Al, alot of info on the 20V's @ Collins 20v group @ yahoo.com, if you need more 20v info contact me @ [email protected], Dudley Parkin/W5DUD ----- Original Message ----- From: "D. Chester" <[email protected]> To: <[email protected]> Sent: Saturday, February 14, 2009 2:09 PM Subject: Re: [AMRadio] Broadcast transmitter rescue
>>> So my question to the group. Who is the Collins 20v-2 guru and how much >>> will >>> be involved to move it from 610khz to 1885khz. >>> >>> 73, Al K3TKJ > > Why be content to operate on just ONE frequency? > > It is very easy to convert those xtal oscillator stages to function as > buffer stages for an external VFO, and to make rf stages the rig tuneable > across the band so that the rig will function with VFO or multiple xtals. > > If you have a VFO with low impedance output, and capable of at least 0.25 > watts, the best solution is to ground the grid of the xtal oscillator > stage, > disconnect any feedback circuitry going to the cathode, add an rf choke > from > cathode to ground if necessary, and inject the rf signal from the VFO > directly to the cathode through a coupling capacitor. That is what I do > with my Gates BC1-T and homebrew HF-300 transmitter. With the other > homebrew rig presently tuned to 40m, I inject the VFO signal directly to > the > control grid of the 6AG7 1st buffer/amplifier stage. > > I converted my BC1-T to external VFO, which is a modified T-368 m.o. unit, > and it will tune from 1800 to 2000 with all the transmitter tuned circuits > accessible from the front panel, and the neutralisation holds perfectly > from > one end of the band to the other without readjustment. > > One of the faults I find with much of the present-day AM operation on 160 > and 75 is the same as with the SSB dead-air groups: insisting on operating > on one and only one frequency, with daily 8 to 10 member roundtables > amidst > QRM from adjacent QSO's less than 5 kHz away in both directions, while > there > may be tens of kHz of vacant space in other parts of the band. We need to > spread out a little and maintain more widespread AM presence throughout > the > bands, with reasonable sized QSO's and roundtable groups. > > Don k4kyv > > > ______________________________________________________________ > Our Main Website: http://www.amfone.net > AMRadio mailing list > Searchable Archives: http://www.mail-archive.com/[email protected]/ > List Rules (must read!): http://w5ami.net/amradiofaq.html > List Home: http://mailman.qth.net/mailman/listinfo/amradio > Post: [email protected] > To unsubscribe, send an email to [email protected] with > the word unsubscribe in the message body. > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
