Nice to know you're still around! I would be interested in a new QSK card. Anyone else?
-------------- Original message -------------- From: "Scott Prather" <[EMAIL PROTECTED]> > > "Scott Prather" made an utterance to the drakelist > gang > ---------------------------------------------------------------------- > Ron: First of all, I'd like to thank Jim for providing such thorough > information to the group concerning my original article "Improving the Drake > TR-7". It's good to know that there's still interest in these modifications. > > At the time I wrote the article 15 years ago, the M/A Com MA4P4002D PIN > diode was expensive but obtainable. It was also as perfect a component as > you could find for this particular application. But as anyone who has looked > for one of these diodes knows, they are completely unobtainable. I've toyed > with a few potential substitutes, but I'm not happy with what I've tried so > far. Consequently, I'm considering a redesign of the QSK card's RF switching > portion to utilize currently-available components. If there's enough > interest in a redesigned QSK card for the TR-7, I may be able to move this > up my priority list. > > Also, if anyone on this list has questions regarding the original four > modifications described in my Summer, 1992, Communications Quarterly > article, please feel free to contact me directly: N7NB "at" att.net. > > Scott Prather > N7NB > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jim Pruitt > Sent: Wednesday, January 10, 2007 9:01 PM > To: DrakeList > Cc: Ron Wagner > Subject: Re: [drakelist] Specs for TR7 mod > > > "Jim Pruitt" made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Hello Ron. > > Here is a link to Scott's comments about the article: > http://www.dproducts.be/Drake_Museum/tr-7mods.htm > > I will paste them below then comment some more after the Prather comments > that are copied from JM Cherry's great Drake web page: > > "Improving the Drake TR-7 by Scott D. Prather, N7NB (ex-KB9Y) > Reversible Modifications Enhance Performance > Please Note: The mailing address included on the first page of this article > is no longer current. Please address all correspondence to Scott Prather at: > [EMAIL PROTECTED] > Abstract. > The Drake TR-7 is an outstanding all-band, solid-state transceiver that was > a trendsetter when it was unveiled to the amateur radio market in 1978. > However, the TR-7 was not without its problems, some of which included: > Poor receive performance below 1.5 MHz > No full break-in (QSK) CW operation > Compromised signal/noise ratio when using narrow CW filters > High cooling fan noise, and the stock fan operates only when the radio is > powered from an AC source > > My article, which originally appeared in the Summer, 1992, issue of > Communications Quarterly, addresses these four problems with modifications > that require no drilled holes, making them 100% reversible. > Notes > Improving the TR-7 is reprinted here in its entirety, and it appears on the > Web with the permission of Communications Quarterly. I scanned the original > 19-page paper and converted it into an Adobe R PDF file. The size of this > file is approximately 1.9 MB, so it will take a while to download if you are > using dial-up Internet access. For example, at 28.8 kbps it took me about 14 > minutes to download the file. > Component Availability > At the time that this article was written, all of the components required > for these modifications were readily available. However, there are a few > components that are currently difficult to obtain. The most difficult > component to locate is D2005 (MA4P4002D), a stud-mount, high-power PIN diode > manufactured by M/A COM. It's my understanding that this diode is no longer > available from the manufacturer, and I've been unable to locate a diode that > I'm convinced will function as a substitute. The MA4P4002D has the following > specifications at 25 degrees Celsius: > > Series Resistance @ 100 mA forward current: 0.5 ohms > Carrier Lifetime: 6 microseconds @ 100 mA forward current > Voltage Rating: 200 Volts > Power Dissipation: 15 watts > Initially, my decision to use M/A COM's stud-mounted PIN diode was driven by > the requirement to support 100% duty cycle operation, such as RTTY or SSTV. > However, for low duty-cycle modes such as SSB and CW, I have successfully > used the MA4P4002B axial-lead PIN diode with a small heat sink on the diode > body. Unfortunately, this diode is not readily available either. Generally, > any axial-lead PIN diode capable of dissipating about 5 watts and meeting > the series resistance, voltage rating, and carrier lifetime specifications > listed above should function in a low duty cycle application at the 150W > power level of the TR-7. I will continue my search for a substitute, and > I'll post my findings here. If anyone has a suggestion for a substitute, > please send the information to me at the e-mail address listed above. > The second component that's difficult to obtain is reed-relay K2001, > manufactured by Magnecraft. I've been unable to locate a source for this > part, however, it appears that an EAC P/N 20-1121-30 reed relay should work > in its place. The primary difference between the original Magnecraft part > and the EAC substitute is the lead pinout. The EAC relay has short in-line > pins, while the Magnecraft part had longer leads which would permit a > "triangular" PC pad configuration at each end. Also, the NC contact on the > EAC part is on the opposite side of the relay from the Magnecraft part. > However, minor redrilling of the PC board along with a jumper to the NC > contact will solve these minor compatibility problems. > Miscellaneous: > A minor change in operation is required if a TR-7 is modified with my QSK > card and subsequently used to transceive with a Drake R-7 receiver using the > Drake 1548 cable. Because the QSK card RX Mute line only functions when the > TR-7 is turned on, the R-7 will be muted if the "Mute" button is depressed > and the TR-7 is turned off. To use the R-7 when the TR-7 is off, just > release the R-7 "Mute" button. > > Errata: > Although I carefully reviewed this article prior to its publication, in a > project of this scope some errors are bound to occur. The known errors are: > > Page 22, Figure 3: Two minor labeling errors exist in this schematic. There > are two capacitors labeled C2002, one connected to point "C" and the other > to the drain of Q2002. The capacitor connected to point C should be C2006. > Also, there are two capacitors labeled C2005, one connected to point "I" and > one from L2002 to ground. The capacitor from L2002 to ground should be > C2007. > Page 24, Figure 6: The RX coax ground connection point (K) is shown > incorrectly. This ground should be tied to the RF ground point that comes up > to the NO contact of relay K2001. This point is just to the left and below > the ground point (K) shown in Figure 6. Photo E on page 29 details the > correct location for (K). > Page 32, top left-hand column: The wires connected to points F and G on the > QSK card were reversed. The list of wire colors should read as follows: > 4) Connect the tan wire to point D > 5) Connect the pink wire to point E > 6) Connect the red wire to point F > 7) Connect the blue wire to point G > Page 37, Fan Control Parts List: Although it's not specifically stated, > temperature-sensitive zener diode D4001 is in a type TO-92 case. Also, C4001 > should be 1.0 m F, 35 volts, not the 25 volt capacitor listed. > If anyone has questions concerning the modifications in this article or > availability of components, please contact me via e-mail at > [EMAIL PROTECTED] > 73 > Scott Prather > N7NB" > > end of http://www.dproducts.be/Drake_Museum/tr-7mods.htm direct quote. > > > > Mr. Cherry also has the PDF of the Communications Quarterly article as a > link just below the comments above but that PDF does not have the resolution > on the pictures like the Comm Quarterly did and the reprint that John > Loughmiller did in his book "R.L. Drake A Family Affair" but Scott Prather > redrew the schematics in the book to make them easier to follow. > > I was unable to find the Magnecraft W104MIP42 for a reasonable price (as you > also discovered). A friend (who is or was on this list at one time) > redesigned the pc board for me so it is laid out for the EAC part that Scott > recommends. It USED TO BE SOLD BY DIGIKEY and was used in some other very > recent QSK articles (a VE ham had an article in QEX in spring of 2006 that > used them) but Digikey no longer stocks it since EAC went to a rediculous > minimum order for Digikey. I talked to EAC and they said they would sell > direct to me but they had a $500 minimum (I think). The relay was about $8 > from Digikey when they had them. Digikey lists the relay as "Call" so if a > few of us call maybe they would stock a few more. > > Hold the phone! I just checked Digikey's web site and they have 80 of the > EAC relays in stock right now at $5.75 each and stock number Z645-ND so they > must have mananged to convince EAC to change their minimum but they do have > them and cheaper than the ones that I got. > > As for the MA/Com Diodes (MA4P4002D) those are unobtainable! You can still > get the MAP4002B from Richardson Electronics (they sell mainly to 2 way > companies I think) and they were around $8 each when I bought my 4. They > are in the DO style case like a 1N4007 diode (I forget what the DO# is) and > so it will not disipate the power like the MA4P4002D but it is the same > specs. I had asked Scott about using a 1N4001 as was suggested on another > list I am on but Scott did not seem to think it would work very well so the > MAP4002B is your best bet and is ok unless you are going to run RTTY or a > similar mode that requires 100% duty cycle. > > Anyway I do have a pc board layout for the QSK board using the EAC relay > footprint. You can also get a board set from Fred at Far Circuits. If I > remember right the EAC relay had one contact swapped with the W104MIP42 so > you could put it on the FAR boards and then redo those 2 contacts. The EAC > relay pin out is in sort of a triangle (kind of like many pc board mounted > pots) on each end so 3 contacts on each end but the center contact is moved > in some but the outer contacts are in line. > > You did not mention the front end board but I had a little trouble finding > the RSD-12V Aromat relays for that. Rich Measures AG6K - telephone, [805] > 386-3734 at http://www.somis.org/ had them and are part of one of his > amplifier mod kits. I think they were about $12 each. I also found a few > on ebay later. I kept getting caught because the specs even on the RSD-12V > say it is spst but it is REALLY SPDT. Even the legend on the relay does not > show it but if you check the contacts you will find that it is indeed spdt! > The RS-12V is spst but the RSD-12V is spdt. > > I hope that you find the above information helpful. Most of it comes from > Scott Prather himself and posted on JM Cherry's web site at > http://www.dproducts.be/Drake_Museum/tr-7mods.htm and some of the parts info > was from my experience in trying to find the parts. I have done searches > for some of the info before but usually my comments on this Drakelist in the > past are what I find! > > Good luck and if I can help with more info or the Prather QSK pc board > layout for the EAC style relay please let me know. > > Thank you. > > Jim Pruitt > > > > ----- Original Message ----- > From: "Ron Wagner" > To: > Sent: Tuesday, January 09, 2007 5:06 PM > Subject: [drakelist] Specs for TR7 mod > > > > > > Ron Wagner made an utterance to the drakelist gang > > ---------------------------------------------------------------------- > > Good evening all, > > I am looking at the modifications in the Comm Qtrly mag Summer 1992 by > > Scott Prather. Can anyone tell me about the specs on the reed relay > > by Magnecraft W104MIP-42? Things like current, voltage, switching speed, > > etc. > > > > I see there are a couple places on the web who have them for ~$70 which > > seems a bit expensive to me. Maybe they are special enough to demand that > > price, but I am thinking maybe not. > > > > I would like to try the QSK mod, but need to find that relay's specs and > > see if I can sub something for the pin diode. I know that diode will be > > a killer, so I am trying the relay first. > > > > 73, > > WD8SBB > > ---------------------------------------------------------------------- > Submissions: drakelist@www.zerobeat.net > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in > body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ---------------------------------------------------------------------- > > ---------------------------------------------------------------------- > Submissions: drakelist@www.zerobeat.net > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ----------------------------------------------------------------------
