Differences

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--- radios:dr-m06th [2025/04/13 06:17] – m0mzf
+++ radios:dr-m06th [2025/04/24 11:08] (current) – m0mzf
@@ Line 1: / Line 1: @@
 ======Modifying an Alinco DR-M06TH 6m transciever for packet usage======
+{{:radios:dr-m06th:dr-m06th-stockpic.jpg?nolink&400|}}
-Finding an affordable single-band FM radio for 6m is a challenge, occasionally these Alincos turn up on eBay so I nabbed one tried my hand at modifying it. As it turns out they're well built, old-skool analogue and a breeze to work on - after tapping the discriminator / modulator the radio was bench tested using an 857D and a pair of NinoTNCs; it works on 4k8 IL2Pc beautifully. The main issue with testing was those Aerial Facilities dummy loads are **superb** at 50MHz!
+Finding an affordable single-band FM radio for 6m is a challenge, occasionally these Alincos turn up on eBay so I nabbed one tried my hand at modifying it. As it turns out they're well built, old-skool analogue architecture and a breeze to work on. The [[https://www.manualslib.com/products/Alinco-Dr-M06th-3260732.html|service manual]] is widely available online and is superb.
-The PA puts out ~20W and can be adjusted using VR1. The deviation is adjusted with VR2 and is set ~5KHz from the factory. On receive it's (apparently) very selective & sensitive, and the second IF filter is 20KHz wide so this TRX might even work on wider bandwidth modes. Anecdotal testing using an IC-705 as a reference receiver the wideband PLL phase noise looks to be very low and there are no horrendous key-up transients a-la FTM-1500.
+The PA puts out ~20W and can be adjusted using VR1. The deviation is adjusted with VR2 and is set ~5KHz from the factory. On receive it's (apparently) very selective & sensitive, and the second IF filter is 20KHz wide so this TRX might even work on wider bandwidth modes. Using an IC-705 as a reference receiver the wideband PLL phase noise looks to be very low and there are no horrendous key-up transients a-la FT-1500M.
+After tapping the discriminator / modulator the radio was bench tested using an 857D and a pair of NinoTNCs; it works on 4k8 IL2Pc beautifully. The main issue with testing was those Aerial Facilities dummy loads are **superb** at 50MHz!
 Ready to go as GB7WIN's 6m port! Live long and prosper little Alinco.
-=====Schematic=====
+=====Schematic detail=====
 {{:radios:dr-m06th:dr-m06th-schem.jpg?nolink&960|}}
   * Pin 11 of IC3 is the output from the discriminator
-  * The junction between C25 and C26 is the output of the de-emphasis filter
+  * The junction between C25 and C26 is the output of the de-emphasis filter and before the squelch pull-down transistors Q4 and Q16
   * The junction of VR2 / R24 / R25 / R123 is the modulator input, via the deviation pot VR2 and coupling capacitor C40
   * CP11 is the input to the mic preamplifier, pre-emphasis filter & modulator drive buffer amplifier
@@ Line 58: / Line 61: @@
 None yet. When I get access to my DSO and find someone with a specan I'll post the results up here.
+----
+de M0MZF, April '25