thanks Pete and Bernie i'll do that. i have a HT20 that uses that tube. Rob K5UJ
On Fri, Feb 12, 2010 at 5:38 PM, Bernie Doran <[email protected]> wrote: > Fair radio in Lima, Ohio had a huge stock of them, I believe thousands at a > very reasonable price, give them a call or email. Bernie W8RPW > ----- Original Message ----- > From: "Rob Atkinson" <[email protected]> > To: "Discussion of AM Radio in the Amateur Service" > <[email protected]> > Sent: Friday, February 12, 2010 1:55 PM > Subject: Re: [AMRadio] AMRadio Digest, Vol 73, Issue 11 > > > Jim, where do you get a 4D32 these days? > > thanx > > rob > K5UJ > >> >> Jack, >> >> First off, I have an HT-20 on the air and it does well on AM, so the >> problem is not generic to the transmitter design. I have not used a light >> bulb for a dummy antenna, at least not recently, but my average-reading >> watt meter does not bobble during modulation. I would expect a light bulb >> to get brighter during modulation, not dimmer, which is something you also >> know. >> >> From the list of things that Larry suggested, above, I would not think >> that #1 would not be a cause of this particular problem. Human voice audio >> is not symmetric, so you can achieve more full modulation by selecting the >> better phasing connection, but neither phasing connection should cause >> "downward modulation." #5 is also not likely to be the problem if the rig >> has the original modulation transformer. The other suggestions are all >> likely causes. Another one might be a very flat (low gain, low emission) >> 4D32 final amplifier tube. >> >> Let me know how much final grid drive you are running and what the loaded >> plate current is for the final amp. The manual recommends 260 ma plate >> current for CW and 320 ma for phone, but I don't run any more than 200 ma >> for either phone or CW. 4D32's are too expensive! It also recommends 10 ma >> for grid current. The ARRL Handbook ratings for a 4D32 are a maximum of >> 240 ma for CW and 220 ma for phone, with 12 ma of grid current for the CW >> condition and 10 ma for phone. I can compare your operating parameters to >> the ones I'm running currently on my rig. Mine is tuned up on 14286 right >> now in anticipation of the Classic Exchange AM event on Sunday. >> >> Good luck, >> >> Jim Hanlon, W8KGI >> ______________________________________________________________ >> > ______________________________________________________________ > 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 > ______________________________________________________________ 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
