There is a big difference between the Micor or Mastr II station that was factory built for a specific frequency or group of frequencies and an inexpensive mass marketed radio that is built by the thousands on a production line.
Same thing as what a paging system operator told me about an early order of pagers manufactured in Asia that he purchased quite a few years ago. The pagers had rotten performance and after a lot of complaining an engineer showed up to see what was going on. After examining a pager the engineer pulled a small bag from his pocket and replaced the crystal filters. Now the pager worked great. The paging system owner said something to the effect of "great, how soon will you have this change in place as I want to get some more product?" The response was along the lines of "we have 10,000 units in stock, when they are gone we will get build more with the new filters". The decision was to simply deal with the people who complained or sent a unit in for repair instead of trying to fix all of the defective product. It is regrettable that some manufacturers choose shortcuts but it is a result of the mass marketing philosophy that enables us to be able to purchase radios that cover wide frequency ranges for less than $200-300. Milt N3LTQ ----- Original Message ----- From: "Eric Lemmon" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Thursday, March 15, 2007 11:13 PM Subject: RE: [Repeater-Builder] Amateur-Grade Radios (Was: Fixed Audio) > Chuck, > > You are absolutely correct! However, the specific resistor value used for > R405 in each MICOR station was deliberately selected to result in the > desired deviation level. Thus, the R405 resistor value (nominally 33 > kohms) > varies from one station to the next. Note 409 on the schematic for the > MICOR TLD5320A Exciter states that "R404 and R405 are factory selected so > that Private Line deviation falls between 500 Hz and 1000 Hz limits." > > The point I made was that Alinco, among many other manufacturers, simply > used a certain value in almost every radio built, rather than a selected > value, with the assumption that it would result in "enough" CTCSS > deviation. > As I pointed out, that value more often than not resulted in CTCSS > deviation > that was far above the appropriate or necessary level. However, as Bob > points out, a very few Alinco models have CTCSS deviation adjustment pots, > but those are the exception. > > Without exception, every Alinco radio I have tested- portable or mobile- > has > had CTCSS deviation above 1000 Hz. That is far too high, and it usually > results in talk-off due to tone distortion. As others have noted, this > issue of over-deviation of CTCSS tones is definitely not limited to > Alinco, > but is common practice in Amateur-grade radios. > > Lest others doubt the accuracy of my measurements, I should state that > both > of my service monitors have annual calibrations performed by the original > vendors, with certifications traceable to the NIST. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Kelsey > Sent: Thursday, March 15, 2007 3:45 AM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Amateur-Grade Radios (Was: Fixed Audio) > > Commercial radios also used fixed values. The Micor is one example of > fixed > values for tone deviation. > > Chuck > WB2EDV > > ----- Original Message ----- > From: "Mike Morris WA6ILQ" <[EMAIL PROTECTED] > <mailto:wa6ilq%40pacbell.net> >> > To: <Repeater-Builder@yahoogroups.com > <mailto:Repeater-Builder%40yahoogroups.com> > > Sent: Wednesday, March 14, 2007 11:37 PM > Subject: Re: [Repeater-Builder] Amateur-Grade Radios (Was: Fixed Audio) > >> At 07:23 PM 03/14/07, Eric Lemmon WB6FLY wrote: >>>Nate, >>> >>>Several years ago, I chastised ARRL Labs for failing to report the basic >>>2-way radio performance parameters of 12dB SINAD sensitivity, voice >>>deviation limit, CTCSS deviation limit, and center frequency accuracy. I >>>did not get a satisfactory answer, but I suspect that there is a >>>reluctance >>>to disparage the performance of name-brand Ham radios. >> >> QST survives on the ads. The league doesn't want to risk the revenue. >> As the wise man said, he who has the gold makes the rules. >> >>>Nearly every Amateur 2m radio I have tested has CTCSS deviation far in >>>excess of the EIA/TIA recommended level of 750 Hz, and that level is not >>>adjustable in most radios. >> >> Pots cost more than fixed resistors and that would reduce the profits. > > > > > > > > Yahoo! Groups Links > > >
