FT1000D Transmit Carrier Point (TCP) Page
This TCP Page details the required adjustments to the FT1000D transmit carrier
point to take full advantage of the wider InRad crystal filters and capacitor changes.
Note 3 details all of this.
The detailed 'how-to-do' instructions for the TCP adjustment are contained in the table entitled "TCP Adjustment for Highest Frequency Offset".
This report details the radio carrier set point adjustment using the modified TCP procedure for the new InRad filters
(#715 and #716) in the FT1000D.
When the InRad filters were installed the low frequency response was, to say the least, overpowering!! The attached graph
(FTaud1f.gif) shows the results of the modified TCP adjustment BEFORE (old Yaesu filters) and AFTER (new InRad plus TCP
adjustment). Note that the extreme low frequency response has been 'shifted' upward to gain the added high frequency
Radio Adjustment with Modified TCP Procedure:
This procedure is modified from the TCP procedure outlined in the FT1000D Service Manual, page 15. The intent is to end up with 'enough' low frequency response but to get as much high frequency audio response as possible. You may of course like to have a bit more low frequency audio response, so feel free to change the low frequency limit as necessary. However after listening to the results of my adjustment, no lower response is needed. Some may want to move the TCP to around 100 hz to gain as much high frequency audio response as possible with minimal effect on lower frequencies.
QUESTIONS & ANSWERS:
Some have asked . . "do I need to change the audio capacitors on the AF UNIT board if I install the new InRad filters? Won't the new filters give me the required audio bandwidth without making the changes"?
The answer is NO!! Without changing of the AF UNIT Board's capacitors, the low end frequency response cannot be pushed down since all audio low frequency information is cut off due to the values of these capacitors.
The following measurements are courtesy of W6RU. He installed the InRad filters into a stock FT1000D that did NOT HAVE THE AUDIO CAP MODS until they were added at the 3rd last measurement (in GREEN) in the table below. Note that the low frequency response could NOT be obtained until the cap changes were made. Lastly, I've included my radio's present response for contrast. Note the difference in the filters employed.
* = Filters are InRad #715 and InRad #716
In summary, there are THREE (3) procedures necessary to change the FT-1000D's audio. They are;
1) replace present filters with two (2) InRad filters on the IF FILTER board,
2) change four (4) audio capacitor values on the AF UNIT board,
3) adjust the carrier offset via the TCP adjustment on the LOCAL UNIT board as outlined below.
W8CQ, Jeff sent me data showing the results on his FT1000D with both InRad filters (715, 716) along with the 'cap' mods plus TCP adjustment all summarized in one great chart. Good job, Jeff!
The replacement of one InRad filter (#715) with an InRad #707 filter (Collins Mechanical Filter would increase the low and high frequency response as shown in table above (in RED).
TCP ResultsThe results of the TCP adjustment is shown here. Note that a audio signal generator or a set of pre-recorded tones (100hz and 3100hz is all that's necessary) to make this adjustment. The input signal is fed into the standard 8 pin mic connector and adjusted according to the directions provided.
The object is to obtain the greatest amount of high frequency response while balancing that with the low frequency response. The scales should be tilted in favor of high frequency response.
To make the highest possible carrier offset adjustment, use this procedure.
The signal generator was found to be 150hz off at 3Khz and around 20hz at 100 hz so the frequency data in the X axis is not quite correct. You need to mentally add the correction factors. After receiving SpectraPlus, the signal generator was recalibrated to remove this error. The SP plots are, of course, correct.
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